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Is San Ramon Tap Water Safe to Drink?

Yes! Generally Safe to Drink*

LAST UPDATED: 7:49 pm, July 21, 2022
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Table of Contents

Can You Drink Tap Water in San Ramon?

Yes, San Ramon's tap water is generally considered safe to drink as San Ramon has no active health based violations of the Safe Drinking Water Act (SDWA) that we are aware of. Other factors such as lead piping in a home, or low levels of pollutants on immunocompromised individuals, should also be considered, however. To find more recent info we might have, you can check out our boil water notice page or the city's water provider website.

According the EPA’s ECHO database, from April 30, 2019 to June 30, 2022, San Ramon's water utility, Dublin San Ramon Services District, had 0 violations of the Safe Drinking Water Act. For more details on the violations, please see our violation history section below. This assessment is based on the Dublin San Ramon Services District water system, other water systems in the city may have different results.

While tap water that meets the EPA health guidelines generally won’t make you sick to your stomach, it can still contain regulated and unregulated contaminants present in trace amounts that could potentially cause health issues over the long-run. These trace contaminants may also impact immunocompromised and vulnerable individuals.

The EPA is reviewing if it’s current regulations around pollutant levels in tap water are strict enough, and the health dangers posed by unregulated pollutants, like PFAS.

Water Quality Report for San Ramon Tap Water

The most recent publicly available numbers for measured contaminant levels in San Ramon tap water are in its 2020 Water Quality Report. As you can see, there are levels which the EPA considers to be acceptable, but being below the maximum allowable level doesn’t necessarily mean the water is healthy.

Lead in tap water, for example, is currently allowed at up to 15ppb by the EPA, but it has set the ideal goal for lead at zero. This highlights how meeting EPA standards doesn’t necessarily mean local tap water is healthy.

EPA regulations continue to change as it evaluates the long term impacts of chemicals and updates drinking water acceptable levels. The rules around arsenic, as well as, lead and copper are currently being re-evaluated.

There are also a number of "emerging" contaminants that are not currently. For example, PFAS (Per- and polyfluoroalkyl substances), for which the EPA has issued a health advisory. PFAS are called "forever chemicals" since they tend not to break down in the environment or the human body and can accumulate over time.

We recommend looking at the contaminants present in San Ramon's water quality reports, or getting your home's tap water tested to see if you should be filtering your water.

San Ramon Tap Water Safe Drinking Water Act Violation History - Prior 10 Years

Below is a ten year history of violations for the water system named Dublin San Ramon Services District for San Ramon in California. For more details please see the "What do these Violations Mean?" section below.

Is there Lead in San Ramon Water?

Based on the EPA’s ECHO Database, 90% of the samples taken from the San Ramon water system, Dublin San Ramon Services District, between sample start date and sample end date, were at or below, 0.01 mg/L of lead in San Ramon water. This is 66.7% of the 0.015 mg/L action level. This means 10% of the samples taken from San Ramon contained more lead.

While San Ramon water testing may have found 0.01 mg/L of lead in its water, that does not mean your water source has the same amount. The amount of lead in water in a city can vary greatly from neighborhood to neighborhood, or even building to building. Many buildings, particularly older ones, have lead pipes or service lines which can be a source of contamination. To find out if your home has lead, we recommend getting you water tested.

No amount of lead in water is healthy, only less dangerous. As lead accumulates in our bodies over time, even exposure to relatively small amounts can have negative health effects. For more information, please check out our Lead FAQ page.

Are there PFAS in San Ramon Tap Water?

Currently, testing tap water for PFAS isn’t mandated on a national level. We do have a list of military bases where there have been suspected or confirmed leaks. There appears to be at least one military base - Camp Parks - near San Ramon with suspected leaks.

With many potential sources of PFAS in tap water across the US, the best information we currently have about which cities have PFAS in their water is this ewg map, which you can check to see if San Ramon has been evaluated for yet.

Our stance is better safe than sorry, and that it makes sense to try to purify the tap water just in case.

What do these Violations Mean?

Safe Drinking Water Act Violations categories split into two groups, health based, and non-health based. Generally, health based violations are more serious, though non-health based violations can also be cause for concern.

Health Based Violations

  1. Maximum contaminant levels (MCLs) - maximum allowed contaminant level was exceeded.
  2. Maximum residual disinfectant levels (MRDLs) - maximum allowed disinfectant level was exceeded.
  3. Other violations (Other) - the exact required process to reduce the amounts of contaminants in drinking water was not followed.

Non-Health Based Violations

  1. Monitoring and reporting violations (MR, MON) - failure to conduct the required regular monitoring of drinking water quality, and/or to submit monitoring results on time.
  2. Public notice violations (Other) - failure to immediately alert consumers if there is a serious problem with their drinking water that may pose a risk to public health.
  3. Other violations (Other) - miscellaneous violations, such as failure to issue annual consumer confidence reports or maintain required records.

SDWA Table Key

Field Description
Compliance Period Dates of the compliance period.
Status Current status of the violation.
  • Resolved - The violation has at least one resolving enforcement action. In SDWIS, this indicates that either the system has returned to compliance from the violation, the rule that was violated was no longer applicable, or no further action was needed.
  • Archived - The violation is not Resolved, but is more than five years past its compliance period end date. In keeping with the Enforcement Response Policy, the violation no longer contributes to the public water system's overall compliance status. Unresolved violations are also marked as Archived when a system ceases operations (becomes inactive).
  • Addressed - The violation is not Resolved or Archived, and is addressed by one or more formal enforcement actions.
  • Unaddressed - The violation is not Resolved or Archived, and has not been addressed by formal enforcement.
show details
Health-Based? Whether the violation is health based.
Category Code
The category of violation that is reported.
  • TT - Treatment Technique Violation
  • MRDL - Maximum Residual Disinfectant Level
  • Other - Other Violation
  • MCL - Maximum Contaminant Level Violation
  • MR - Monitoring and Reporting
  • MON - Monitoring Violation
  • RPT - Reporting Violation
show details
Code A full description of violation codes can be accessed in the SDWA_REF_CODE_VALUES (CSV) table.
Contaminant Code A code value that represents a contaminant for which a public water system has incurred a violation of a primary drinking water regulation.
Rule Code Code for a National Drinking Water rule.
  • 110 - Total Coliform Rule
  • 121 - Surface Water Treatment Rule
  • 122 - Long Term 1 Enhanced Surface Water Treatment Rule
  • 123 - Long Term 2 Enhanced Surface Water Treatment Rule
  • 130 - Filter Backwash Rule
  • 140 - Ground Water Rule
  • 210 - Stage 1 Disinfectants and Disinfection Byproducts Rule
  • 220 - Stage 2 Disinfectants and Disinfection Byproducts Rule
  • 230 - Total Trihalomethanes
  • 310 - Volatile Organic Chemicals
  • 331 - Nitrates
  • 332 - Arsenic
  • 333 - Inorganic Chemicals
  • 320 - Synthetic Organic Chemicals
  • 340 - Radionuclides
  • 350 - Lead and Copper Rule
  • 410 - Public Notice Rule
  • 420 - Consumer Confidence Rule
  • 430 - Miscellaneous
  • 500 - Not Regulated
  • 111 - Revised Total Coliform Rule
show details
Rule Group Code Code that uniquely identifies a rule group.
  • 120 - Surface Water Treatment Rules
  • 130 - Filter Backwash Rule
  • 140 - Groundwater Rule
  • 210 - Stage 1 Disinfectants and Disinfection Byproducts Rule
  • 220 - Stage 2 Disinfectants and Disinfection Byproducts Rule
  • 230 - Total Trihalomethanes
  • 310 - Volatile Organic Chemicals
  • 320 - Synthetic Organic Chemicals
  • 330 - Inorganic Chemicals
  • 340 - Radionuclides
  • 350 - Lead and Copper Rule
  • 400 - Other
  • 500 - Not Regulated
  • 110 - Total Coliform Rules
  • 410 - Public Notice Rule
  • 420 - Consumer Confidence Rule
  • 430 - Miscellaneous
show details
Rule Family Code Code for rule family.
  • 100 - Microbials
  • 200 - Disinfectants and Disinfection Byproducts Rule
  • 300 - Chemicals
  • 400 - Other
  • 500 - Not Regulated
show details

For more clarification please visit the EPA's data dictionary.

San Ramon Water - Frequently Asked Questions

HOW IN THE WORLD DOES 3 WATER GET TO THE TRI-VALLEY?
Progress at Patterson Pass: 13 THE LATEST IN WATER TREATMENT UPGRADES No more wondering: 11 SEE HOW WATER TREATMENT WORKS! PLUS: PAGE Drought conditions: 10 HOW YOU CAN BE WATER WISE Emergency preparedness:
WHAT’S IN YOUR WATER?
Water Quality Testing As part of rigorous quality control, Zone 7 Water Agency regularly checks for a range of substances in our water supplies to ensure we can deliver safe and clean water to customers. The results table shows the average level and range of each detected regulated contaminant in our water supplies. Detected secondary standards and additional parameters are also listed. The following components may be of interest to our customers: TURBIDITY is a measure of the cloudiness of the water. We monitor it because it is a good indicator of the effectiveness of the filtration system for surface water treatment. TOTAL ORGANIC CARBON (TOC) has no health effects. However, TOC provides a medium for the formation of disinfection byproducts. These byproducts include trihalomethanes (THMs) and haloacetic acids (HAAs). Drinking water containing these byproducts in excess of the maximum contaminant levels (MCL) may lead to adverse health effects, including liver or kidney problems, nervous-system effects, and increased cancer risk. TOC removal requirements are applicable to surface water treatment plants only. NITRATE in drinking water at levels above 10 mg/L (as nitrogen) is a health risk for infants less than six months of age. Such nitrate levels in drinking water can interfere with the capacity of the infant’s blood to carry oxygen, resulting in a serious illness; symptoms include shortness of breath and blueness of the skin. Nitrate levels above 10 mg/L may also affect the ability of the blood to carry oxygen in other individuals, such as pregnant women and those with certain specific enzyme deficiencies. If you are caring for an infant, or you are pregnant, you should ask advice from your health care provider. Nitrate levels in Zone 7’s surface water supplies are typically very low (less than 1 mg/L) as compared to groundwater, but both sources meet all standards.
HOW TO READ THE TABLE
1 The contaminant being tested for in our labs.
WHERE DO CONTAMINANTS COME FROM?
The sources of drinking water (both tap and bottled water) include rivers, lakes, streams, ponds, reservoirs, springs and wells. As water travels over the surface of the land or through the ground, it dissolves naturally-occurring minerals and, in some cases, radioactive material, and it can pick up substances resulting from the presence of animals or from human activity. Contaminants that may be present in source water include: MICROBIAL CONTAMINANTS, such as viruses and bacteria that may come from wastewater-treatment plants, septic systems, agricultural-livestock operations, landscaping, agriculture and wildlife. INORGANIC CONTAMINANTS, such as salts and metals, that can be naturally occurring or result from urban stormwater runoff, industrial or domestic wastewater discharges, oil and gas production, mining, or farming.
HOW DO WE ENSURE WATER SAFETY?
About Water Treatment As part of rigorous quality control, Zone 7 Water Agency regularly checks for a range of substances in our water supplies to ensure we can deliver safe and clean water to customers. The world of water treatment is complex! There is a great deal of work that goes into preparing the water that originates as rain, snowmelt or underground aquifers to meet the Zone 7 water quality goals, so that it can be delivered to homes and businesses. Our water treatment process is carefully designed and managed, taking water from different sources through multiple steps and stages before it reaches you. Thanks to best-in-class systems and a highly skilled team of experts, you can be confident in drinking Zone 7 water, straight from the tap. Zone 7 Water Agency applies a multi-barrier approach from source to tap to safeguard water supplies and achieve the high quality we expect from our drinking water. Our approach to water treatment includes the following multi-step process: Best management practices to protect our watersheds and wellfields. Treatment processes for surface water supplies, which remove particles and greater than 99% of waterborne pathogens, including viruses.
HOW DO I CONTACT SAN RAMON CUSTOMER SERVICE?
To contact customer service for the San Ramon water provider, Dublin San Ramon Services District, please use the information below.
By Phone: 925-875-2367
By Email: dmartin@dsrsd.com
By Mail: 7051 DUBLIN BLVD
DUBLIN, CA, 94568-3018
HOW TO PAY BILL FOR DUBLIN SAN RAMON SERVICES DISTRICT
Already have an account?

Existing customers can login to their Dublin San Ramon Services District account to pay their San Ramon water bill by clicking here.

Want to create a new account?

If you want to pay your Dublin San Ramon Services District bill online and haven't made an account yet, you can create an account online. Please click here to create your account to pay your San Ramon water bill.

Want to pay without an account?

If you don't want to make an account, or can't remember your account, you can make a one-time payment towards your San Ramon water bill without creating an account using a one time payment portal with your account number and credit or debit card. Click here to make a one time payment.

HOW TO START & STOP SAN RAMON WATER SERVICE
Starting Your Service

Moving to a new house or apartment in San Ramon means you will often need to put the water in your name with Dublin San Ramon Services District. In order to put the water in your name, please click the link to the start service form below. Start service requests for water bills typically take two business days.

Start Service Form

Want to create a new account?

Leaving your house or apartment in San Ramon means you will likely need to take your name off of the water bill with Dublin San Ramon Services District. In order to take your name off the water bill, please click the link to the stop service form below. Stop service for water bills requests typically take two business days.

Stop Service Form

USER SUBMITTED RATINGS

San Ramon tap water
  • Drinking Water Pollution and Inaccessibility 30% Low
  • Water Pollution 40% Moderate
  • Drinking Water Quality and Accessibility 70% High
  • Water Quality 60% High

The above data is comprised of subjective, user submitted opinions about the water quality and pollution in San Ramon, measured on a scale from 0% (lowest) to 100% (highest).

Related FAQS

San Ramon Water Quality Report (Consumer Confidence Report)

The EPA mandates that towns and cities consistently monitor and test their tap water. They must report their findings in an annual Consumer Confidence Report. Below is the most recent water quality report from San Ramon's Water. If you would like to see the original version of the report, please click here.

2020

Annual Consumer Confidence Report

DIVE INTO THE HIGHLIGHTS:

Results of 2020 water quality tests

PAGE

8

How in the world does 3 water get to the Tri-Valley?

Progress at Patterson Pass: 13

THE LATEST IN WATER

TREATMENT UPGRADES

No more wondering: 11

SEE HOW WATER

TREATMENT WORKS!

PLUS:

PAGE

Drought conditions: 10

HOW YOU CAN BE WATER WISE

Emergency preparedness: 9

ALWAYS A GOOD TIME FOR PREP

WELCOME TO THE WONDROUS WORLD OF WATER

With a commitment to excellence, Zone 7 provides high-quality water for residences and businesses throughout the Tri-Valley area. You can be confident that Zone 7 is actively monitoring the quality of your water with our state-of- the-art treatment and monitoring systems.

Zone 7 delivers treated drinking water to four major water retailers, along with a small number of direct customers, serving over a quarter million people in Pleasanton, Livermore, Dublin and the Dougherty Valley area of San Ramon. Zone 7 also provides untreated water to local agricultural users and provides flood protection to 425 square miles of eastern Alameda County. Working closely with our partners, we pride ourselves at Zone 7 on not only meeting but also exceeding all state and federal health standards. That’s why we developed our own Zone 7 goals– setting a higher bar for the quality of our water.

This collaborative approach makes a world of difference in ensuring our water supply is safe, clean and sustainable. Through comprehensive programs of planning, source water protection, treatment and monitoring, Zone 7 has been able to achieve internal water quality goals that are more stringent than regulatory standards. This report represents a combination of strategic investment in advanced treatment infrastructure, rigorous testing and our commitment to transparency in sharing these results.

Rest assured, all Zone 7 water supplied in 2020 met the regulatory standards set by the state and federal governments and, in almost all cases, the quality was significantly better than required.

1

ZONE 7 ESSENTIAL WORKERS RESPOND TO COVID-19

Zone 7 Water Agency has actively monitored guidance from public health authorities throughout the COVID-19 pandemic. We want our customers to know that the safety and reliability of your water is Zone 7’s highest priority. The standard treatment and disinfectant processes used for Zone 7 water are highly effective against viruses, including COVID-19.

Your water is safe to drink and use every day.

Our highly trained staff at Zone 7 work around the clock to ensure the quality and safety of your water. These essential workers have remained diligent and dedicated to serving the Tri-Valley’s needs during ever- changing requirements for remote work, events and social distancing. Through it all, we are proud that our committed staff of public servants have maintained consistent service and quality for our customers.

COVID-19 is transmitted person-to person, not through water, according to the Centers for Disease Control and Prevention. Additional information is available at: www.cdc.gov/coronavirus/2019-ncov/php/water.html

2

WHERE IN THE WORLD DOES THE TRI-VALLEY’S WATER COME FROM?

Source Water Assessment

Zone 7 Water Agency draws from a diverse portfolio of drinking water sources, including local and imported surface water as well as groundwater from wells. We carefully monitor all these sources to ensure their continued quality and to protect the safety of our water supply.

A source water assessment is conducted on each groundwater well as required by the California State Water Resources Control Board (State Water Board). Sanitary surveys for surface water supplies are conducted every five years. The latest sanitary survey for the California Delta and the State Water Project (SWP) was completed in June 2017.

Protecting our source water is an important part of providing safe drinking water to the public that meets the stringent Zone 7 water quality goals. By monitoring for potential contaminants, we can proactively address threats to water quality. For example, groundwater sources can be vulnerable to releases from chemical/petroleum pipelines, leaking tanks, groundwater contamination plumes, septic tanks, and wastewater-collection systems. Surface water can become contaminated as it travels through the Sacramento and San Joaquin watersheds and the Delta. After leaving the Delta, water is transported to Zone 7 via the South Bay Aqueduct (SBA). The SBA water quality can become polluted from local cattle grazing, wildlife activities, and recreational activities in the watersheds of the Bethany and Del Valle reservoirs. In order to deliver the high-quality water we expect in Zone 7, we proactively participate

in a number of activities to improve water supply reliability and the water quality of the SBA.

Copies of any public outreach materials, source water assessment reports or sanitary surveys are available by calling

Gurpal Deol at:

925-447-0533.

29%

Ground

2020

Water

71%

ZONE 7

Surface

WATER

Water

SUPPLY

 

 

SOURCES

Our Primary Water Sources

The water that flows from your tap originated from a number of sources – including snowpack, rainfall and underground aquifers.

IMPORTED SURFACE WATER. . The majority of our water supply originates as Sierra Nevada snowmelt and is conveyed by the State Water Project through the Delta and then via the South Bay Aqueduct.*

LOCAL SURFACE WATER. This is comprised of local rain runoff stored in Del Valle Reservoir.

GROUNDWATER. This supply, carefully managed by Zone 7, is pumped from the aquifer that underlies the Livermore-Amador Valley; water in the aquifer comes from local rainfall and from strategic recharges made with imported water to ensure access during dry years.

  • In wet years, we store surplus SWP supplies in local and offsite groundwater basins for use when needed, and for reliability during droughts.

3

THE TRI-VALLEY WATER

SUPPLY JOURNEY

The majority of the Tri-Valley’s water supply is imported from outside the region, on average 70% of our water comes from the Sierra Nevada Mountains and arrives via the South Bay Aqueduct. We also are fortunate to have the Livermore Valley Groundwater Basin in our area. This important natural resource provides approximately 10% of our water supply in any given year, though we must be strategic about managing this resource sustainably to ensure the

basin is not overdrawn. We also receive water in the form of rainfall stored in our local reservoir, Lake Del Valle. Dry seasons, such as the one we are experiencing now, mean we use different sources of water, which are treated differently as well.

  • Follow the path of our source water in the infographic below.
  • See page 11-12 for information on how we treat different types of source water, or visit our website at www.zone7water.com/waterquality to watch our Wondrous World of Water videos.

ZONE 7

WATER

SUPPLY

Patterson Pass

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4

WHAT ARE PFAS AND WHY IS EVERYONE TALKING ABOUT THEM?

PFAS (Per- and Polyfluoroalkyl Substances) Information

PFAS are contaminants of emerging concern that are widely used in manufacturing multiple products present in our daily lives. People can be exposed to them through food, packaging, air pollution, dust and drinking water. The health impacts of PFAS on humans are not yet fully understood, but the U.S. Environmental Protection Agency (EPA) states, “There is evidence that exposure to PFAS can lead to adverse health outcomes in humans.”

Zone 7 Water Agency tests water supplies for PFAS – and we proactively take necessary steps if contaminants exceed certain levels. All water delivered to our customers meets or exceeds state and federal regulations, including the new state guidelines for PFAS.

One place that PFAS have been found to accumulate is in groundwater. Thus, monitoring for PFAS and taking actions to reduce the level of these contaminants is part of Zone 7’s comprehensive approach to water quality.

 

 

 

 

 

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COOKWAR

 

 

 

 

 

 

 

 

 

 

 

PFAS Regulatory Update

Over the past several years, the science on PFAS and its impacts to the environment and public health have prompted regulatory actions. The EPA has a 70 nano- grams per liter (ng/L) Lifetime Health Advisory for two types of PFAS, perfluorooctanesulfonic acid (PFOS) and perfluorooctanoic acid (PFOA), either singly or combined, and is moving forward with regulatory development for these two PFAS. The California State Water Resources Control Board has issued drinking water advisory levels for three PFAS (including PFOS and PFOA) so far and is pursuing advisory levels for six additional PFAS found throughout the state. The State Water Board is also in the process of developing Public Health Goals (PHGs) for PFOA and PFOS, which is the first step in establishing a Maximum Contaminant Levels (MCLs) for these PFAS.

State Regulatory Advisory

Levels for PFAS (ng/L)*

PFAS

Notification

Response

Level

Level

 

 

 

 

Perfluorooctanesulfonic acid (PFOS)

6.5

40

Perfluorooctanoic acid (PFOA)

5.1

10

Perfluorobutanesulfonic acid (PFBS)

500

5,000

 

 

 

* When a contaminant is found at concentrations greater than its advisory level, certain notification requirements and recommendations apply.

5

Monitoring Water Supplies

 

 

 

Protecting Water Quality

 

 

 

At Zone 7, protecting public health and safety is the

Zone 7 has been proactive in monitoring for PFAS

highest priority, including actively monitoring for

in water supplies well before any requirements took

PFAS in groundwater and surface water supplies.

effect because we know PFAS tend to accumulate in

 

 

 

 

 

 

groundwater and are commonly found in groundwater

 

 

 

 

 

 

sources throughout the developed world. Because

In 2020, Zone 7 did not detect any PFAS

 

they are so common, it can be difficult or impossible

 

to link PFAS to a single source, and multiple sources

in its treated surface water supplies, which

 

 

can accumulate over time. Zone 7 recently completed

made up the majority of the total water

 

 

a PFAS Potential Source Investigation Study in

delivered to its customers.

 

 

 

 

 

 

 

 

December 2020 to assist in characterizing the extent

 

 

 

 

 

 

of PFAS across Tri-Valley’s groundwater basin and to

 

 

 

 

 

 

 

 

 

 

 

 

identify potential sources of contamination. At this

No PFAS have been detected in Zone 7’s Hopyard

time, there is no indication of a single source for this

contamination because of the widespread prevalence

wellfield. Although Zone 7 detected some PFAS

of PFAS in thousands of consumer products and

in certain wells, this groundwater was blended

there are no known local manufacturing sites.

and/or treated using reverse osmosis to reduce

Zone 7 also has completed a PFAS Treatment Feasibility

the contaminant level below the applicable

 

response level – ensuring that water delivered

Study in summer of 2020 and is in the process of

to our customers met our high standards.

 

planning and designing a new PFAS treatment

2020 PFAS Monitoring Summary

 

facility at the COL wellfield to ensure compliance

 

with anticipated new state regulations in 2025.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

PFAS**** (ng/L)

 

 

 

 

 

WATER SUPPLY SOURCES

 

PFOS

PFOA

PFBS

PFHxS

PFHxA

 

 

 

Average

Range

Average

Range

Average

Range

Average

Range

Average

Range

 

Mocho Wellfield*

 

 

 

 

 

 

 

 

 

 

 

 

Mocho Well 2 (before treatment)**

41

40 - 41

5

5 - 5

7

7 - 7

34

34 - 35

6

6 - 7

 

Mocho Well 3

33

30 - 35

5

5 - 5

6

5 - 7

26

22 - 28

5

5 - 6

 

Mocho Well 4

14

12 - 15

ND

ND

5

5 - 5

15

14 - 17

ND

ND

 

Blended/Treated Mocho Water

24

18 - 30

ND

ND - 4

4

ND - 6

20

16 - 24

ND

ND - 5

 

Chain of Lakes (COL) Wellfield

 

 

 

 

 

 

 

 

 

 

 

 

COL Well 1

32

28 - 38

ND

ND - 5

5

4 - 6

24

21 - 29

ND

ND - 5

 

COL Well 2

14

13 -15

ND

ND

ND

ND

14

12 - 15

ND

ND

 

COL Well 5 (before treatment)***

31

15 - 46

ND

ND

ND

ND

17

9 - 24

ND

ND

 

Blended COL Water

22

19 - 25

ND

ND

ND

ND - 4

17

14 -20

ND

ND

 

Stoneridge Well

10

8 - 16

 

ND

ND

ND

ND - 6

12

9 - 18

ND

ND

 

Hopyard Wellfield (Well 6 and 9)

ND

ND

ND

ND

ND

ND

ND

ND

ND

ND

 

Treated Surface Water

ND

ND

ND

ND

ND

ND

ND

ND

ND

ND

 

Learn More

Zone 7 will continue to closely monitor the quality of the community’s drinking water supplies. As the science advances, we will utilize proven technologies and best practices to ensure that any emerging PFAS issues are managed in a transparent and responsible manner. For more details about PFAS in Zone 7’s water supply and how we are ensuring the safety of your water,

visit www.Zone7Water.com/pfas

NOTES: ng/L = nano grams per liter; ND indicates no detection at or above the Consumer Confidence Report Detection Level (CCRDL) which is 4 ng/L for the above analytes; ND or value in range column indicates that more one sample was collected.

*Mocho 1 Well is a standby emergency well that was not used in 2020.

**Mocho Well 2 was blended/treated at the Mocho Groundwater Demineralization Plant (MGDP) whenever the well was online; All Mocho wells can also be treated at the MGDP.

***COL Well 5 was blended with other COL well water whenever it was online.

****Eighteen analytes were tested per EPA method 537.1; Only detected analytes above the CCRDL are shown on the table; PFOS = perfluro-octane sulfonic acid, PFOA = perfluoro-octanoic acid, PFBS = perfluorobutane sulfonic acid,

PFHxA = perfluorohexanoic acid, PFHxS = perfluorohexane sulfonic acid

6

WHAT’S IN YOUR WATER?

Water Quality Testing

As part of rigorous quality control, Zone 7 Water Agency regularly checks for a range of substances in our water supplies to ensure we can deliver safe and clean water to customers. The results table shows the average level and range of each detected regulated contaminant in our water supplies. Detected secondary standards and additional parameters are also listed. The following components may be of interest to our customers:

TURBIDITY is a measure of the cloudiness of the water. We monitor it because it is a good indicator of the effectiveness of the filtration system for surface water treatment.

TOTAL ORGANIC CARBON (TOC) has no health effects. However, TOC provides a medium for the formation of disinfection byproducts. These byproducts include trihalomethanes (THMs) and haloacetic acids (HAAs). Drinking water containing these byproducts in excess of the maximum contaminant levels (MCL) may lead to adverse health effects, including liver or kidney problems, nervous-system effects, and increased cancer risk. TOC removal requirements are applicable

to surface water treatment plants only.

NITRATE in drinking water at levels above 10 mg/L (as nitrogen) is a health risk for infants less than six months of age. Such nitrate levels in drinking water can interfere with the capacity of the infant’s blood to carry oxygen, resulting in a serious illness; symptoms include shortness of breath and blueness of the skin. Nitrate levels above 10 mg/L may also affect the ability of the blood to carry oxygen in other individuals, such as pregnant women and those with certain specific enzyme deficiencies. If you are caring for an infant, or you are pregnant, you should ask advice from your health care provider. Nitrate levels in Zone 7’s surface water supplies are typically very low (less than 1 mg/L) as compared to groundwater, but both sources meet all standards.

7

Terms to Know

MAXIMUM CONTAMINANT LEVEL (MCL): The highest level of a contaminant that is allowed in drinking water. Primary MCLs are set as close to the Public Health Goals or Maximum Contaminant Level Goals as is economically and technologically feasible. Secondary MCLs are set to protect the odor, taste and appearance of drinking water.

MAXIMUM CONTAMINANT LEVEL GOAL (MCLG): The level of a contaminant in drinking water below which there is no known or expected risk to health. MCLGs are set by the USEPA.

MAXIMUM RESIDUAL DISINFECTANT LEVEL (MRDL): The highest level of a disinfectant allowed in drinking water. There is convincing evidence that addition of a disinfectant is necessary for control of microbial contaminants.

MAXIMUM RESIDUAL DISINFECTANT LEVEL GOAL (MRDLG): The level of a drinking water disinfectant below which there is no known or expected risk to health. MRDLGs do not reflect the benefits of the use of disinfectants to control microbial contaminants.

PUBLIC HEALTH GOAL (PHG): The level of a contaminant in drinking water below which there is no known or expected risk to health. PHGs are set by the California Environmental Protection Agency.

PRIMARY DRINKING WATER STANDARD (PDWS): MCLs and MRDLs for contaminants that affect health, along with their monitoring and reporting requirements, and water-treatment requirements.

TREATMENT TECHNIQUE (TT): A required process intended to reduce the level of a contaminant in drinking water.

REGULATORY ACTION LEVEL (AL): The concentration of a contaminant which, if exceeded, triggers treatment or other requirements that a water system must follow.

RUNNING ANNUAL AVERAGE (RAA): Test results based on an average of the previous four quarters.

RANGE: Range of detected results from Not Detected (ND) to the highest test result based on all samples collected during the year.

How to Read the Table

 

 

STATE STANDARDS

 

ZONE 7 RESULTS

 

 

 

 

 

 

PHG

SURFACE WATER

GROUNDWATER

 

 

 

 

DLR

(MCLG)

 

 

 

 

 

 

 

 

 

 

 

 

 

CONTAMINANT

MCL

(MRL)

[MRDLG]

RAA

Range

RAA

Range

 

1

2

3

4

5

6

7

8

 

Selenium μg/L

50

5

30

ND

ND

ND

ND-10

 

 

 

 

 

 

 

 

 

 

 

1 The contaminant being tested for in our labs.

  1. The highest level of a contaminant allowed for drinking water. Our results must be lower than this amount.
  2. The level at which we must report our results, even though they are lower than the standard.
  3. Goal levels at which the state would like to keep our results below.
  4. Running Annual Average (RAA) of Surface Water test results
  5. Range of results from Surface Water samples
  6. Running Annual Average (RAA) of Groundwater test results
  7. Range of results from Groundwater samples

2020 WATER QUALITY TESTING RESULTS

JANUARY-DECEMBER 2020 WATER QUALITY DATA - CONTAMINANTS DETECTED IN WATER SUPPLY

Primary Drinking Water Standards, established by the State Water Resources Control Board, Division of Drinking Water (DDW)

CONTAMINANT

MCL

DLR

PHG

 

 

 

 

Major Sources in Drinking Water

(MCLG)

 

 

 

 

 

 

(MRL)

[MRDLG]

 

 

 

 

 

Total Coliform Bacteria

5.0% of monthly

 

(0)

 

Highest Percentage of Monthly Positive Samples

Naturally present in the environment

 

samples are positive

 

 

 

1.1

 

 

 

Total Trihalomethanes (TTHMs), µg/L

80

1*

NA

Highest Locational Running Annual Average

Range of All Samples Collected in 2019

Byproduct of drinking water disinfection

 

41

 

19 - 66

Haloacetic Acids (five) (HAA5), µg/L

60

1*

NA

 

16

 

4.8 - 19

 

Chloramines as Chlorine, mg/L

Maximum Residual Disinfectant

 

[4]

System-wide Running Annual Average (RAA)

Range of Monthly Average Chloramines

Drinking water disinfectant added for treatment

 

Level (MRDL) = 4.0

 

 

 

2.6

 

2.5 - 2.8

 

Water Supply Sources

 

 

 

 

 

 

 

 

CONTAMINANT

 

 

 

SURFACE WATER

GROUND WATER

 

Turbidity

TT = 1 NTU maximum

 

NA

Highest Level Found= 0.20 NTU

 

NA

Soil runoff

 

TT= 95% of samples ≤ 0.3 NTU

 

NA

% of samples ≤ 0.3 NTU=100

 

NA

 

Total Organic Carbon

TT= Quarterly RAA Removal

 

NA

Lowest Quarterly RAA Ratio = 1.5

 

NA

Various natural and manmade sources

 

Ratio ≥ 1.0

 

 

 

 

 

 

 

Inorganic Chemicals

 

 

 

Average

Range

Average

Range

Erosion of natural deposits.

Aluminum (µg/L)

1000

50

600

ND

ND

ND

ND - 65

Barium (µg/L)

1000

100

2000

ND

ND

149

ND - 374

Erosion of natural deposits; discharge of drilling wastes; and discharge from metal refineries

Bromate (µg/L)

10

5

0.1

ND

ND - 6

NA

NA

Byproduct of drinking water disinfection

Chromium total (µg/L)

50

10

(100)

ND

ND

ND

ND - 14

Erosion of natural deposits; discharge from steel and pulp mills and chrome plating

Selenium (µg/L)

50

5

30

ND

ND

ND

ND - 8

Erosion of natural deposits; discharge from mines and industrial wastes.

Fluoride (mg/L)

2

0.1

1

ND

ND - 0.1

ND

ND - 0.1

Erosion of natural deposits and discharge from fertilizer and aluminum factories

Nitrate (as Nitrogen) (mg/L)

10

0.4

10

ND

ND - 0.8

2.5

0.9 - 4.4

Erosion of natural deposits; runoff from fertilizer use; and leaching from septic tanks and sewage

Radionuclides

 

 

(0)

3

3

3

ND - 6

Erosion of natural deposits

Gloss Alpha Particle Activity (pCi/L)**

15

3

Uranium (pCi/L)

20

1

0.43

ND

ND

1

ND - 4

Erosion of natural deposits

Secondary Drinking Water Standards, established by DDW

Conductivity (µS/cm)

Chloride (mg/L)

Iron (µg/L)

Sulfate (mg/L)

Total Dissolved Solids (mg/L)

Turbidity (NTU)

1600

500

300

500

1000

5

0.5 –

(0.05) –

522

377 - 657

83

43

-

137

ND

ND

 

 

46

13

-

80

293196 - 355

NDND - 0.12

968

656 - 1486

108

46 - 187

ND

ND - 122

6837 - 128

574399 - 866

0.06ND - 0.69

Substances that form ions when in water; seawater influence Runoff/leaching from natural deposits; seawater influence Leaching from natural deposits; industrial wastes Runoff/leaching from natural deposits; industrial wastes Runoff/leaching from natural deposits

Soil runoff

Additional Parameters - included to assist consumers in making health or economic decisions, i.e. low-sodium diet, water softening, etc.

Alkalinity as calcium carbonate (mg/L)

Boron (µg/L)

Total Hardness as calcium carbonate (mg/L)

Potassium (mg/L)

Sodium (mg/L)

pH (Units)

Silica (mg/L)

100 –

83

62 - 140

152

ND - 300

101

70 - 140

2.62 - 3.5

7050 - 93

8.57.5 - 8.9

8.22.8 - 15

283

194

- 419

821

270

- 1360

345

205

- 521

2.121.5 - 3.5

7831 - 129

7.57.2 - 7.7

2518 - 30

Naturally-occuring minerals Naturally-occuring mineral Naturally-occuring minerals Naturally-occuring mineral Naturally-occuring mineral Naturally-occuring minerals Naturally-occuring mineral

NOTES:

  • TTHMs each component DLR is 1 μg/L. HAAs each component DLR is 1 μg/L except Monochloroacetic acid that has DLR of 2 μg/L.
    ** = Gross alpha data is from 2017.

ABBREVIATIONS / UNITS: MCL = Maximum Contaminant Level, DLR = Detection Limit for Purposes of Reporting (State Water Board established), MRL

  • Minimum Reporting Level, NA = Not Applicable, PHG = Public Health Goal, MCLG = Maximum Contaminant Level Goal, MRDLG = Maximum Residual Disinfectant Level Goal, RAA = Running Annual Average, TT = Treatment Technique, NTU = Nephelometric Turbidity Unit, µg/L = Micrograms per liter, mg/L = Milligrams per liter, µS/cm = Microsiemens per centimeter, pCi/L = Pi- cocuries per liter, ND = Monitored for but not detected at or above DLR or MRL.

So, how much is THAT? Let’s compare:

There are about 2.5 million liters of water in

mg/L = Milligrams/Liter

µg/L = Micrograms/Liter

ng/L = Nanograms/Liter

an Olympic-size swimming pool. To make the

or parts per million (ppm)

or parts per billion (ppb)

or parts per trillion (ppt)

pool as salty as the ocean, it would take 2

About 2 quarts

About 1/2 teaspoon

About 1 pinch

standard shipping containers full of salt!

of salt in the pool

of salt in the pool

of salt in the pool

 

Where Do Contaminants Come From?

The sources of drinking water (both tap and bottled water) include rivers, lakes, streams, ponds, reservoirs, springs and wells. As water travels over the surface of the land or through the ground, it dissolves naturally-occurring minerals and, in some cases, radioactive material, and it can pick up substances resulting from the presence of animals or from human activity. Contaminants that may be present in source water include:

MICROBIAL CONTAMINANTS, such as viruses and bacteria that may come from wastewater-treatment plants, septic systems, agricultural-livestock operations, landscaping, agriculture and wildlife.

INORGANIC CONTAMINANTS, such as salts and metals, that can be naturally occurring or result from urban stormwater runoff, industrial or domestic wastewater discharges, oil and gas production, mining, or farming.

PESTICIDES AND HERBICIDES, which may come from a variety of sources such as agriculture, urban stormwater runoff, and residential uses.

ORGANIC CHEMICAL CONTAMINANTS, including synthetic and volatile organic chemicals, which are byproducts of industrial processes and petroleum production. They can also come from gas stations, urban stormwater runoff, and septic systems.

RADIOACTIVE CONTAMINANTS which can be naturally occurring or be the result of oil and gas production and mining activities.

In order to ensure that tap water is safe to drink, the USEPA and the State Water Board prescribe regulations that limit the amount of certain contaminants in water provided by public water systems. The U.S. Food and Drug Administration regulations and California law also establish limits for contaminants in bottled water that provide the same protection for public health.

8

EMERGENCY PREPAREDNESS: ALWAYS A GOOD TIME FOR PREP

California’s unpredictable climate means long dry spells in the summer often followed by sudden heavy rainstorms during the winter.

Our emergency preparedness guru, Flood Ready Freddy, has lots of great tips to make sure you don’t get caught off guard when storms approach.

  • Prepare an emergency kit
  • Have an evacuation plan
  • Keep storm drains clear of debris
  • Maintain overgrown vegetation

You can watch and share videos, one-sheets, checklists and resources that will help you, your family and friends prepare for all different types of emergencies.

Visit zone7water.com/floodready to become a #ReadyFreddy, too!

9

Contaminants Not Detected in Zone 7’s Water Supply

PRIMARY STANDARDS: CONTAMINANTS NOT DETECTED IN ZONE 7 WATER SUPPLY

Organic Chemicals

 

Inorganic Chemicals

Radionuclides***

VOLATILE ORGANIC

SYNTHETIC ORGANIC

Arsenic

Radium-226, Radium-228

CHEMICALS (VOCs)

CHEMICALS (SOCs)*

Antimony

Beta/photon emitters

Benzene

Alachlor

Asbestos

Tritium, Strontium-90

Beryllium

 

Carbon Tetrachloride

Atrazine

 

Cadmium

 

1,2-Dichlorobenzene

Bentazon

 

Cyanide

 

1,4-Dichlorobenzene

Benzo(a)pyrene

 

Mercury

 

1,1-Dichloroethane

Carbofuran

 

Nickel

 

1,2-Dichloroethane

Chlordane

 

Nitrite (as nitrogen)

 

1,1-Dichloroethylene

2,4-D

 

Perchlorate

 

cis-1,2-Dichloroethylene

Dalapon

 

Thallium

 

trans-1,2-Dichloroethylene

Dibromochloropropane (DBCP)

 

Zinc

 

Dichloromethane

Di(2-ethylhexyl)adipate

 

 

 

 

1,2-Dichloropropane

Di(2-ethylhexyl)phthalate

 

 

 

 

NOTES:

 

1,3-Dichloropropene

Dinoseb

 

 

Ethylbenzene

Diquat

 

None of the primary standards listed above were detected at or above

Methyl-tert-butyl ether (MTBE)

Endothall

 

DLR in Zone 7 water supply during 2020 monitoring.

Monochlorobenzene

Endrin

 

 

 

Styrene

Ethylene Dibromide (EDB)

 

 

 

1,1,2,2-Tetrachloroethane

Glyphosate

 

 

 

Tetrachloroethylene

Heptachlor

 

 

 

 

 

 

Toluene

Heptachlor Epoxide

 

SECONDARY STANDARDS: CONTAMINANTS

1,2,4-Trichlorobenzene

Hexachlorobenzene

 

NOT DETECTED IN ZONE 7 WATER SUPPLY

1,1,1-Trichloroethane

Hexachlorocyclopentadiene

 

 

 

1,1,2-Trichloroethane

Lindane

 

Color

Methyl-tert-butylether (MTBE)

Trichloroethylene

Methoxychlor

 

 

Copper

Odor-Threshold

Trichlorofluoromethane

Molinate

 

 

Foaming Agents (MBAS)

Silver

1,1,2-Trichloro-1,2,2-Trifluoroethane

Oxamyl

 

 

Manganese*

Thiobencarb

Vinyl Chloride

Pentachlorophenol

 

Xylenes

Picloram

 

 

 

 

Polychlorinated Biphenyls

 

NOTES:

 

 

Simazine

 

 

 

Thiobencarb

 

*Manganese was detected above the DLR during internal operational

 

 

samples, but the average remained below the secondary standard.

 

Toxaphene

 

 

2,3,7,8-TCDD (Dioxin)

 

None of the secondary standards listed above were detected at or above

 

1,2,3-Trichloropropane (TCP)

 

DLR in Zone 7 water supply during 2020 monitoring.

 

2,4,5-TP (Silvex)

 

 

 

 

 

 

 

 

Lead and Copper Rule and

Corrosion Control

Zone 7 Water Agency and its retailers have been in compliance with the Lead and Copper Rule requirements for many years and we continue actively monitoring for lead and copper in our delivered water. In addition, Zone 7 completed a corrosion control treatment evaluation study

in September 2017 to ensure existing processes are optimized for corrosion control.

The following monitoring data is for Zone 7’s direct customers only. Per State Water Board approval, compliance monitoring is conducted once every three years. Data from June 20, 2018 monitoring is summarized below:

CONTAMINANT

NUMBER OF

90TH PERCENTILE

NUMBER OF SITES

ACTION LEVEL (AL)

PHG

SAMPLES COLLECTED

LEVEL DETECTED

EXCEEDING AL

Lead (µg/L)

11

4.1

None

15

0.2

Copper (µg/L)

11

71

None

1300

300

If present, elevated levels of lead can cause serious health problems, especially for pregnant women and young children. Lead in drinking water is primarily from materials and components associated with service lines and home plumbing. Zone 7 Water Agency is responsible for providing high quality drinking water, but cannot control the variety of materials used in plumbing components. When your water has been sitting for several hours, you can minimize the potential for lead exposure by flushing your tap for 30 seconds to 2 minutes before using water for drinking or cooking. If you are concerned about lead in your water, you may wish to have your water tested. Information on lead in drinking water, testing methods, and steps you can take to minimize exposure is available from the Safe Drinking Water Hotline or at www.epa.gov/safewater/lead.

THE DROUGHT AND WHAT YOU CAN DO ABOUT IT

California Rainfall Shortage

Tri Valley Water Storage

WHAT YOU CAN DO

ABOUT THE DROUGHT

Be Water Wise

California is currently facing the most severe drought since 2012- 2016. Our rainfall is in par with the drought season of 1976-77. We can’t control the weather, but that doesn’t mean we can’t help. Water Wise Wendy is the Tri-Valley’s water saving wizard! She is full of helpful tips and tricks (not to mention costumes, because what kid isn’t?) that will help you find and fix leaks, save water outside in your yard and reduce your use inside your home.

Visit www.zone7water.com/waterwise for shareable videos and

additional resources.

10

HOW DO WE ENSURE WATER SAFETY?

About Water Treatment

As part of rigorous quality control, Zone 7 Water Agency regularly checks for a range of substances in our water supplies to ensure we can deliver safe and clean water to customers. The world of water treatment is complex! There is a great deal of work that goes into preparing the water that originates as rain, snowmelt or underground aquifers to meet the Zone 7 water quality goals, so that it can be delivered to homes and businesses. Our water treatment process is carefully designed and managed, taking water from different sources through multiple steps and stages before it reaches you. Thanks to best-in-class systems and a highly skilled team of experts, you can be confident in drinking Zone 7 water, straight from the tap.

Zone 7 Water Agency applies a multi-barrier approach from source to tap to safeguard water supplies and achieve the high quality we expect from our drinking water. Our approach to water treatment includes the following multi-step process:

SOURCE WATER PROTECTION:

Best management practices to protect our watersheds and wellfields.

CONVENTIONAL DUAL-MEDIA FILTRATION:

Treatment processes for surface water supplies, which remove particles and greater than

99% of waterborne pathogens, including viruses.

11

BLENDING AND/OR FILTRATION:

Treatment through reverse osmosis membranes as needed, to reduce the concentration of minerals and contaminants in the groundwater.

DISINFECTION:

The scientifically proven addition of chemicals to inactivate or kill remaining pathogens.

SAFE STORAGE AND DISTRIBUTION:

Maintaining a consistent disinfectant residual level in the distribution systems to prevent bacterial growth as water travels to your tap.

12

Patterson Pass Water Treatment Plant Ozonation and Expansion Project

This project will modernize the plant so that Zone 7 can continue to meet its commitment to providing a reliable supply of high-quality water. The project will:

  • Increase plant and process reliability by replacing aging treatment facilities
  • Increase plant production capacity from 12 million gallons of water a day (mgd) to 24 mgd
  • Increase in-plant storage capacity of finished water by approximately 5 million gallons
  • Add ozonation facilities to improve treated water quality

Once completed, the Patterson Pass Water Treatment Plant will essentially be a brand new

24-mgd plant and will provide much needed back- up in case of potential outages at the Del Valle Water Treatment Plant. Additional operational flexibility provides for a reliable water supply in the event of emergencies such as earthquakes.

HOW DOES OZONE

TREATMENT WORK?

Adding an electric spark to Oxygen (O2) creates

supercharged Ozone (O￿) molecules.

Contaminants in water may include

bacteria, viruses, and algal byproducts that

impact taste and odor.

Ozone is injected into the water as a gas at our new ozonation site in the Del Valle Water Treatment Plant.

The Ozone seeks out and destroys contaminants in the water.

Ozonation leaves behind pure, high-quality water, without the byproducts left behind by other disinfectants.

Patterson Pass Water Treatment Plant Milestones

1962 Construction of Patterson Pass Water Treatment Plant, with a capacity of 7.5 million gallons per day (mgd).

1969 Plant capacity was expanded to 12 mgd, with the installation of additional filters and treated water storage.

2003 Plant capacity was expanded by 8 mgd, with the installation of a parallel ultrafiltration membrane treatment processes.

2019-2021 Construction of new facilities including an ozone generation building, contactor structures, six filters, chemical storage and feed facilities, a 5-million gallon treated water storage tank, a pump station and new emergency generator. Demolition of aging facilities, including the ultrafiltration membrane treatment processes, and modification of existing clarifiers, wash water recovery ponds, and chemical facilities.

2022 New ozonation process is expected to be fully operational next spring.

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WATER TREATMENT PLANT

OZONATION PROJECTS

Algal Blooms Cause Taste, Odor Impacts

The major source of raw water supply for the Del Valle and Patterson Pass Water Treatment Plants is surface water imported through the Sacramento-San Joaquin River Delta and conveyed via the South Bay Aqueduct. Local runoff from Lake Del Valle can also be treated at the Del Valle Water Treatment Plant.

In recent years, more frequent algal blooms have affected the water we receive for treatment. Seasonal overgrowths of algae can cause taste and odor changes – such as an earthy, musty taste – and make the water more complex to treat. Some algae can also plug up filters and produce toxins. Treating this water supply with conventional treatment processes has become increasingly difficult and costly.

Multiple studies over the years have identified ozone as a more effective alternative to chlorine to make the treatment process more efficient, and to improve finished water quality.

Improvements to Treatment

Process and Finished Water Quality

As part of Zone 7’s commitment to high-quality water, we have completed upgrading the Del Valle Water Treatment Plant to utilize a powerful disinfectant called ozone. The plant can treat up to 40 million gallons of water per day (mgd) and provides majority of water supply in the Tri-Valley. Since late summer of 2020, ozone has replaced chlorine as the primary disinfectant in the treatment process, resulting in even higher quality water for our customers. This project is part of Zone 7’s Capital Improvement Plan and is a capital investment of $49 million, financed through bonds. Approximately $1.3M net increase in annual operating cost is anticipated due to addition of ozone treatment.

Zone 7 is also in the process of upgrading the Patterson Pass Water Treatment Plant to utilize ozone while expanding the plant capacity from 12 to 24 mgd. The new treatment facilities at the Patterson Pass Water Treatment Plant should be fully operational by spring of 2022. This project is a capital investment of $110 million, financed through water rates, new connection fees, and bonds. Approximately $1 million net increase in annual operating and maintenance costs is anticipated to operate the new ozone system and pump station.

This investment in ozonation will improve our water by removing organic substances that cause impact taste and odor, reducing the formation of chlorine-related byproducts, and neutralizing even more pathogens than chlorine. It will make our water cleaner, safer and better tasting – straight from the tap.

Better Tasting,

Safer Water

The transition from chlorine to ozone disinfection is expected to improve the overall quality of water treated at Del Valle Water Treatment Plant to the benefit of our customers. Previously, Zone 7 uses chlorine as a disinfectant to treat raw water. Chlorine is highly effective in killing bacteria and viruses; however, it can react with organic material in the water

to create odors and potentially harmful chemical byproducts.

A powerful oxidant and disinfectant, ozone is bubbled into pretreated raw water as an ozone-in-oxygen gas mixture. It is highly effective

at killing bacteria and neutralizing large pathogens such as Giardia and Cryptosporidium. By adding ozone treatment, Zone 7 will be able to reduce the use of chlorine and minimize potentially harmful disinfection byproducts from chlorine disinfection. Ozone treatment will also reduce the need for other chemicals in the treatment process.

Ozonation is more effective than chlorine at treating organic matter and destroying algal byproducts. This will make our water more palatable by removing many of the compounds that can cause unpleasant taste and odors in drinking water, including those created by algal blooms

that affect our raw water supply.

Adding to its value, ozone treatment is the technology of choice for treating other contaminants

of emerging concern, such as cyanotoxins produced by blue- green algae, endocrine disruptors and pharmaceuticals that can make their way into raw water supplies.

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100 North Canyons Parkway

Livermore, CA 94551

925-454-5000 | www.zone7water.com

Este Informe Contiene Información Muy Importante Sobre Su Agua Potable. Tradúzcalo O Hable Con Alguien Que Lo Entienda Bien. (This Report Contains Important Information About Your Drinking Water. Translate it, or speak with someone who understands it.)

Educational Information

Drinking water, including bottled water, may reasonably be expected to contain at least small amounts of some contaminants. The presence of contaminants does not necessarily indicate that water poses a health risk. More information about contaminants and potential health effects can be obtained by calling the U.S. Environmental Protection Agency’s (USEPA’s) Safe Drinking Water Hotline (1-800-426-4791).

Some people may be more vulnerable to contaminants in drinking water than the general population. Immuno-compromised persons such as persons with cancer undergoing chemotherapy, persons who have undergone organ transplants, people with HIV/AIDS or other immune system disorders, some elderly, and infants can be particularly at risk from infections. These people should seek advice about drinking water from their health care providers. USEPA/Centers for Disease Control (CDC) guidelines on appropriate means to lessen the risk of infection by Cryptosporidium and other microbial contaminants are available from the Safe Drinking Water Hotline (1-800-426-4791).

We Welcome Your Participation

Zone 7 Water Agency is committed to transparency and invites public participation. You are invited to engage in our public forum and voice questions or concerns about your drinking water. Regular meetings of the Board of Directors are open

to the public and held the third Wednesday of each month at 7 p.m. Special meetings are scheduled as needed. Meeting agendas are posted online at www.zone7water.com.

Reminder

Always take extra precautions, the water may be safe to drink when it leaves the sewage treatment plant but it may pick up pollutants during its way to your tap. We advise that you ask locals or hotel staff about the water quality. Also, note that different cities have different water mineral contents.

Sources and Resources

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