District: Bayshore
System: South San Francisco System
A printable version of this report is also available.
Welcome
Cal Water is committed to providing a reliable supply of safe, clean water to our customers and communities, 24 hours per day, 7 days per week, 365 days per year. As water quality regulations have become more stringent, we have added or adjusted treatment to confirm that the water we deliver continues to meet or surpass all standards—because protecting our customers' health and safety is our highest priority.
In this system in 2023, we conducted 12,684 tests on 2,144 water samples for 230 constituents. We are pleased to confirm that we met every primary and secondary federal and state water quality standard last year.
But, our promise to provide quality, service, and value means more than just treating and testing water. It means having expert professionals available to assist with routine services safely and efficiently. It means having personnel available to handle emergencies around the clock. It means maintaining and upgrading the infrastructure needed to transport water from its source through a network of pumps, tanks, and pipes to your tap. It also means that, even with costs increasing across the country, we do everything we can to operate as efficiently as possible to keep your water service affordable.
I encourage you to read this year's water quality report, also called your Consumer Confidence Report, as it details any constituents detected in your water supply in 2023 and shows how your water compares to federal and state standards. It also provides information on hot topics and steps we take to protect your health and safety.
If you have any questions, we are here to help. You can contact your local office by phone or by using the Contact Us form. You can also get water service news on our web site and via our Facebook, X (formerly Twitter), and Instagram pages. If you're an account holder, you can find updates in your monthly bill and should keep your contact information up to date by visiting ccu.calwater.com to make sure you receive emergency and other important information.
Sincerely,
Ross Moilan, District Manager, Bayshore District
Action Items
There were no significant issues in your water system in 2023, and we have no recommended action items for our customers in this area.
Bayshore District
341 North Delaware Street
San Mateo, CA 94401-1727
(650) 558-7800
Your Water System
Cal Water has provided high-quality water utility services in South San Francisco since 1931. In 2023, water for our customers was purchased from the San Francisco Public Utilities Commission (SFPUC). Our South San Francisco system includes 160 miles of main, 14 storage tanks, one collecting tank, 20 booster pumps, six groundwater wells, and one groundwater treatment plant.
Our company-wide water quality assurance program includes vigilant monitoring throughout our systems and testing at our state-of-the-art laboratory. Additionally, we proactively maintain and upgrade our facilities to provide a reliable, high-quality supply.
If you have any questions or concerns, please contact our local office by phone at (650) 558-7800 or through the Contact Us page.
Chloramines
Chloramines are most commonly formed when ammonia is added to chlorine. They are used as a disinfectant to treat your drinking water, and provide long-lasting disinfection as water moves through pipes to consumers.
Water Resource Sustainability
Cal Water helps our customers conserve water by offering programs and incentives to reduce indoor and outdoor water use, develop more efficient habits, and educate the next generation about the importance of managing water resources sustainably. We also continue to invest diligently in our infrastructure to reduce the amount of water lost to pipeline leaks and, in 2022, completed an updated assessment of the impacts of climate change on water supply and demand. Whether in wet or dry years, it's important that we make saving water every day a way of life. Using water wisely will ensure that we have enough water in periods of drought and for generations to come.
Visit the conservation page for details.
The Water Quality Lab
Water professionals collect samples from throughout the water system for testing at our newly upgraded, state-of-the-art water quality laboratory, which is certified each year through the stringent Environmental Laboratory Accreditation Program (ELAP).
Our laboratory team tests the water for 326 constituents with equipment so sensitive it can detect levels as low as one part per trillion. In order to maintain the ELAP certification, all of our scientists must pass blind-study proficiency tests for every water quality test performed. Water quality test results are entered into our Laboratory Information Management System (LIMS), a sophisticated software program that enables us to react quickly to changes in water quality and analyze water quality trends in order to plan effectively for future needs.
Cross-Connection Control
So that the high-quality water we deliver is not compromised in the distribution system, Cal Water has a robust cross-connection control program in place. Cross-connection control is critical to making sure that activities on customers' properties do not affect the public water supply. Our cross-connection control specialists ensure that all of the existing backflow prevention assemblies are tested annually, assess all connections, and enforce and manage the installation of new commercial and residential assemblies.
Backflow can occur when certain pressure conditions exist either in our distribution system or within the customer's plumbing, so our customers are our first line of defense. A minor home improvement project—without the proper protections—can create a potentially hazardous situation, so careful adherence to plumbing codes and standards will keep the community's water supply remains safe. Please be sure to utilize the advice or services of a qualified plumbing professional.
Many water-use activities involve substances that, if allowed to enter the distribution system, would be aesthetically displeasing or could even present health concerns.
Some common cross-connections are:
- Garden hoses connected to a hose bib without a simple hose-type vacuum breaker (available at a home improvement store).
- Improperly installed toilet tank fill valves that do not have the required air gap between the valve or refill tube.
- Landscape irrigation systems that do not have the proper backflow prevention assembly installed on the supply line.
The list of materials that could potentially contaminate the water system is vast. According to the United States Environmental Protection Agency (EPA), a wide variety of substances have contaminated drinking water systems throughout the country as a result of poor cross-connection control. Examples include:
- Antifreeze from a heating system.
- Lawn chemicals from a garden hose or sprinkler head.
- Blue water from a toilet tank.
- Carbonated water from a soda dispenser.
Customers must ensure that all plumbing is in conformance with local plumbing codes. Additionally, state law requires certain types of facilities to install and maintain backflow prevention assemblies at the water meter. Cal Water's cross-connection control staff will determine whether you need to install a backflow prevention assembly based on water uses at your location.
Protecting Our Watersheds
We encourage customers to join us in our efforts to prevent water pollution and protect our most precious natural resource.
The SFPUC conducts watershed sanitary surveys for the Hetch Hetchy source annually and for the local water sources and Upcountry Non-Hetch Hetchy Source (UNHHS) every five years. The latest sanitary surveys for the local watersheds and the UNHHS watershed were completed in 2021 for the period of 2016-2020.
All of these surveys, together with our stringent watershed protection management activities, were completed with support from partner agencies including the National Park Service and U.S. Forest Service. The purpose of the surveys is to evaluate the sanitary conditions and water quality of the watersheds, and to review results of watershed management activities conducted in the preceding years. Wildfire, wildlife, livestock, and human activities continue to be the potential contamination sources.
You may contact the DDW San Francisco District office at (510) 620-3474 to review these reports.
Your 2023 Results
Fluoride
State law requires Cal Water to add fluoride to drinking water if public funding is available to pay for it, and it is a practice endorsed by the American Medical Association and the American Dental Association to prevent tooth decay. In this area, local water is blended with purchased water that has fluoride in it. Show the table in this report to your dentist to see if he or she recommends giving your children fluoride supplements.
More information about fluoridation, oral health, and related issues can be found on the DDW web site.
For general information on water fluoridation, visit the Fluoride page.
Water Hardness
Hardness is a measure of the magnesium, calcium, and carbonate minerals in the water. Water is considered soft if its hardness is less than 75 parts per million (ppm), moderately hard at 75 to 150 ppm, hard between 150 and 300 ppm, and very hard at 300 ppm or higher.
Hard water is generally not a health concern, but it can have an impact on how well soap lathers and is significant for some industrial and manufacturing processes. Hard water may also lead to mineral buildup in pipes or water heaters.
Some people with hard water opt to buy a water softener for aesthetic reasons; however, some water softeners add salt to the water, which can cause problems at wastewater treatment plants. Additionally, people on low-sodium diets should be aware that some water softeners increase the sodium content of the water.
For more information on water hardness, see the water hardness video.
Possible Contaminants
All 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 EPA Safe Drinking Water Hotline at (800) 426-4791.
The sources of drinking water (both tap and bottled) include rivers, lake, 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 can pick up substances resulting from the presence of animals or human activities. Prior to entering the distribution system, source water with constituents over maximum contaminant levels is treated to reduce levels to meet standards set by public health experts.
Contaminants that may be present in source water include:
- Microbial contaminants, such as viruses and bacteria, which may come from sewage treatment plants, septic systems, agricultural livestock operations, and wildlife.
- Inorganic contaminants, such as salts and metals, which 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 compounds, which are byproducts of industrial processes and petroleum production, and can also come from gas stations, urban stormwater runoff, agricultural applications, and septic systems.
- Radioactive contaminants, which can be naturally occurring or the result of oil and gas production and mining activities.
In order to keep tap water safe to drink, the EPA and DDW prescribe regulations that limit the amount of certain contaminants in water provided by public water systems. Food and Drug Administration (FDA) regulations establish limits for contaminants in bottled water, which must provide the same protection for public health.
Some people may be more vulnerable to contaminants in drinking water than the general population. Immunocompromised people, such as those with cancer undergoing chemotherapy, those who have undergone organ transplants, and those with HIV/AIDS or other immune system disorders; some elderly people; and infants can be particularly at risk from infections. These people should seek advice from their health care providers about drinking water contaminants. EPA and Centers for Disease Control and Prevention (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.
About Lead
As the issue of lead in water continues to be top of mind for many Americans, Cal Water wants to assure you about the quality of your water. We are compliant with health and safety codes mandating use of lead-free materials in water system replacements, repairs, and new installations. We have no known lead service lines in our systems. We test and treat (if necessary) water sources to confirm that the water delivered to customer meters meets all water quality standards and is not corrosive toward plumbing materials.
The water we deliver to your home meets lead standards. However, 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 (for example, lead solder used to join copper plumbing, and brass and other lead-containing fixtures).
Cal Water is responsible for providing high-quality drinking water to our customers' meters, but cannot control the variety of materials used in properties' 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 by a certified lab. More information about lead in drinking water can be found through the Safe Drinking Water Hotline (1-800-426-4791) or at www.epa.gov/safewater/lead.
Testing for Lead in Schools
The State of California required that all public schools built before 2010 test for lead in their drinking water by July 1, 2019. We are committed to supporting our school districts' efforts to protect students and ensure that the drinking water at their school sites are below regulatory limits. We worked with all school districts in our service area that serve kindergarten through 12th grade to develop sampling plans, test samples, and conduct follow-up monitoring, if needed, for corrective actions.
Please see our Testing for Lead in Schools web page for more information. For specific information regarding local school data, see the state web portal lead sampling in schools page.
Lead and Copper Rule
The Lead and Copper Rule requires us to test water inside a representative number of homes that have plumbing most likely to contain lead and/or lead solder to determine the presence of lead and copper or any action level exceedance. An action level is the concentration of a contaminant which, when exceeded, triggers corrective actions before it becomes a health concern. If action levels are exceeded, either at a customer's home or system-wide, we work with the customer to investigate the issue and/or implement corrosion control treatment to reduce lead levels.
Lead Service Line Inventory (LSLI)
Protecting our customers' health and safety is our highest priority. As part of this commitment, we have been working to identify and replace any old customer water service lines and fittings that may contain lead. California Senate Bill (SB) 1398 required all water utilities in California to develop an inventory of all distribution service line materials, and submit a list of known lead service lines to the state by 2018. A list of unknown service lines that may contain lead, along with a plan for replacement, was due to the state by July 1, 2020. Known lines must be replaced as soon as possible.
More information regarding LSLI and specific data for each water system can be found on the health and safety code page of the state web site.
In your system, results from our lead monitoring program, conducted in accordance with the Lead and Copper Rule, were below the action level for the presence of lead.
PFAS
In April 2024, the EPA adopted the final water quality regulation for certain per- and polyfluoroalkyl substances (PFAS):
- MCL of 4 ppt for PFOS and PFOA.
- MCL of 10 ppt for PFHxS, PFNA, and GenX.
- Hazard Index of 1.0 combined for PFHxS, PFNA, PFBS, and GenX.
Water systems must begin monitoring for these PFAS within three years (2027), and must comply with the regulation within five years (2029).
At Cal Water, protecting our customers' health and safety is our highest priority, and we are committed to complying with all requirements set by the public health experts. We have been preparing for the EPA regulation and its potential impact on—and any treatment needed in—our systems, and already evaluated the impact of the proposed regulation so that we could be better prepared to comply with the final MCLs.
We also have protocols to test our water sources for compliance with the new MCLs. We have long followed recommendations from DDW, and even went beyond by testing every active source in our California systems years ago. Although not required at the time, we believed it was the right thing to do. In any cases across our service areas where detections were above the levels at which state public health experts have recommended water suppliers take action (the previous response level), we took the affected sources out of service until treatment was/can be installed.
Our active water sources are in compliance with current California response levels, based on the running annual average at each site. The response level, which is the level at which a water system should make operational changes to reduce the concentration of a compound, is set with a margin of protection for all people (including sensitive populations) over a lifetime of exposure.
Additionally, we believe a comprehensive approach is needed to properly address the situation. We urged the EPA to establish a consistent, science-based standard as quickly as feasible, and strongly supported state legislation that will prohibit the sale and use of certain products that contain PFAS, require the certification of accurate testing methods for PFAS, and establish a publicly accessible database that houses the sources of PFAS entering water supplies. We have also filed lawsuits to hold PFAS manufacturers responsible—and ultimately prevent our customers from bearing the costs of treatment, to the extent possible—and are pursuing grants where available to further offset customer cost impacts.
As background, PFAS are manmade compounds that have been used to make carpets, clothing, fabrics for furniture, paper packaging for food, and other materials (e.g., cookware) that are resistant to water, grease, or stains. These compounds are also used for firefighting at airfields, which is one way they have found their way into groundwater in certain areas.
Studies indicate that long-term exposure to PFAS over certain levels could have adverse health effects, including developmental effects to fetuses during pregnancy or infants; cancer; or impacts on liver, immunity, thyroid, and other functions. Potential health effects related to PFAS are still being studied, and research is still evolving on this issue.
More information on PFAS is available on the DDW web site.
Key Definitions
In Compliance: Does not exceed any applicable MCL, SMCL, or action level, as determined by DDW. For some compounds, compliance is determined by averaging the results for one source over a one-year period.
Level 1 Assessment: A Level 1 assessment is a study of the water system to identify potential problems and determine (if possible) why total coliform bacteria have been found in the system.
Level 2 Assessment: A Level 2 assessment is a very detailed study of the water system to identify potential problems and determine (if possible) why an E. coli MCL violation has occurred and/or why total coliform bacteria have been found in the system on multiple occasions.
Maximum Contaminant Level (MCL): The highest level of a contaminant that is allowed in drinking water. Primary MCLs are set as close to the PHGs (or MCLGs) as is economically and technologically feasible. Secondary MCLs (SMCLs) 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 U.S. Environmental Protection Agency.
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.
Notification Level (NL) and Response Level (RL): Health-based advisory levels for unregulated contaminants in drinking water. They are used by DDW to provide guidance to drinking water systems.
Primary Drinking Water Standards (PDWS): MCLs, MRDLs, and TTs for contaminants that affect health along with their monitoring, reporting, and water treatment requirements.
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 without regard to technological or economic feasibility.
Regulatory Action Level (AL): The concentration of a contaminant which, if exceeded, triggers treatment or other requirements that a water system must follow.
Treatment Technique (TT): A required process intended to reduce the level of a contaminant in drinking water.
Variances and Exemptions: Permissions from the State Water Resources Control Board (State Board) to exceed an MCL or not comply with a treatment technique under certain conditions.
Standard Abbreviations
- AL: Action level
- Max: Maximum
- MFL: Million fibers per liter
- Min: Minimum
- N/A: Not applicable
- ND: Constituent not detected
- NL: Notification level
- NTU: Nephelometric turbidity unit
- pCi/L: Picocuries per liter (a measure of radiation)
- ppb: Parts per billion or micrograms per liter (µg/L)
- ppm: Parts per million or milligrams per liter (mg/L)
- ppq: Parts per quadrillion or picogram per liter (pg/L)
- ppt: Parts per trillion or nanograms per liter (ng/L)
- RAA: running annual average
- µS/cm: Microsiemens/centimeter
Table Introduction
Every year, Cal Water performs hundreds of thousands of tests to monitor the quality of our water. If any contaminants are detected, they are included in this annual water quality report. However, most of the contaminants we test for are not detected, so they are not listed.
See the Potential Contaminants web page for a complete list of contaminants we test for.
In the table, water quality test results are divided into four major sections: "Primary Drinking Water Standards," "Secondary Drinking Water Standards," "State-Monitored Contaminants with Notification Levels," and "Unregulated Compounds." Primary standards protect public health by limiting the levels of certain constituents in drinking water. Secondary standards are set for substances that don't impact health but could affect the water's taste, odor, or appearance. Some unregulated substances (hardness and sodium, for example) are included for your information. The State allows us to monitor for some contaminants less than once per year because the concentrations of these contaminants do not change frequently. Some of our data, though representative, are more than one year old.
Substance Sources
- DI: Byproduct of drinking water disinfection
- DS: Drinking water disinfectant added for treatment
- EN: Naturally present in the environment
- ER: Erosion of natural deposits
- FE: Human and animal waste
- FL: Water additive that promotes strong teeth; discharge from fertilizer and aluminum factories
- FR: Runoff and leaching from fertilizer use; leaching from septic tanks and sewage
- IC: Internal corrosion of household plumbing systems
- IM: Discharge from industrial manufacturers
- IO: Substances that form ions when in water
- IW: Industrial waste
- OC: Runoff from orchards; glass and electronics production waste
- OD: Discharges of oil-drilling waste and from metal refineries
- OM: Naturally occurring organic materials
- RU: Runoff/leaching from natural deposits
- RS: Residue from some surface water treatment processes
- SO: Soil runoff
- SW: Seawater influence
- VA: Various natural and manmade sources
- WD: Leaching from wood preservatives
- UR: Unregulated constituents with no source listed and that do not have standardized "source of substance" language
Our testing equipment is so sensitive, it can detect constituents as small as 1 part per trillion. That is equivalent to 1 inch over 15 million miles.
2022 Water Quality
Primary Drinking Water Standards |
||||||||||
| Microbiological | Year Tested | Unit | MCL | PHG (MCLG) | In Compliance | Distribution System-Wide | Source | |||
| Highest Monthly | ||||||||||
| Fecal coliform and E. coli | 2023 | Positive Samples | 01 | (0) | Yes | 0 | FE | |||
| Radiological | Year Tested | Unit | MCL | PHG (MCLG) | In Compliance | Groundwater | SFPUC Water2 | Source | ||
| Range | Average | Range | Average | |||||||
| Uranium | 2023 | pCi/L | 20 | 0.43 (0) | Yes | ND–1.7 | ND | N/A | N/A | ER |
| Inorganic Chemicals | Year Tested | Unit | MCL | PHG (MCLG) | In Compliance | Groundwater | SFPUC Water | Source | ||
| Range | Average | Range | Average | |||||||
| Arsenic | 2023 | ppb | 10 | 0.004 (0) | Yes | ND–3.5 | 2.1 | N/A | N/A | ER, OC |
| Barium | 2022–2023 | ppm | 1 | 2 (2) | Yes | ND–0.16 | ND | N/A | N/A | ER, OD |
| Fluoride3 | 2023 | ppm | 2 | 1 (4.0) | Yes | N/A | N/A | 0.4–2.6 | 0.6 | ER, FL |
| Nitrate as N | 2023 | ppm | 10 | 10 (10) | Yes | 0.75–2.2 | 1.1 | ND–0.6 | ND | ER, FR |
| Lead and Copper | Year Tested | Unit | AL | PHG (MCLG) | In Compliance | Distribution System-Wide | Source | |||
| 90th Percentile | Samples > AL | |||||||||
| Copper | 2022 | ppm | 1.3 | 0.3 | Yes | 0.08 | 0 of 34 | IC, ER, WD | ||
| Lead | 2022 | ppb | 15 | 0.2 | Yes | ND | 0 of 34 | IC, IM, ER | ||
| Disinfection Byproducts | Year Tested | Unit | MCL | PHG (MCLG) | In Compliance | Distribution System-Wide | Source | |||
| Range | Highest Annual Average | |||||||||
| Total haloacetic acids (THAA) | 2023 | ppb | 60 | N/A | Yes | 6.6–43 | 26 | DI | ||
| Total trihalomethane (TTHM) | 2023 | ppb | 80 | N/A | Yes | 12–64 | 40 | DI | ||
| Disinfectants | Year Tested | Unit | MRDL | MRDLG | In Compliance | Distribution System-Wide | Source | |||
| Range | Average | |||||||||
| Total chlorine | 2023 | ppm | 4 | 4 | Yes | 1.2–3.5 | 3.0 | DS | ||
| Surface Water—Turbidity | Year Tested | Unit | MCL | PHG (MCLG) | In Compliance | Groundwater | SFPUC Water | Source | ||
| Highest Level | Lowest Monthly Percent |
Highest Level | Lowest Monthly Percent |
|||||||
| Turbidity4 | 2023 | NTU | TT | N/A | Yes | — | — | 0.60 | 99.4% | SO |
| Surface Water—Total Organic Carbon (TOC) | Year Tested | Unit | MCL | PHG (MCLG) | In Compliance | Range | Average | Range | Average | Source |
| Total organic carbon5 | 2023 | ppm | TT | N/A | Yes | — | — | 1.2–1.8 | 1.5 | VA |
Secondary Drinking Water Standards |
||||||||||
| Contaminants | Year Tested | Unit | SMCL | PHG (MCLG) | In Compliance | Groundwater | SFPUC Water | Source | ||
| Range | Average | Range | Average | |||||||
| Aluminum | 2023 | ppb | 200 | N/A | Yes | N/A | ND | ND–82 | ND | ER, RS |
| Chloride | 2021–2023 | ppm | 500 | N/A | Yes | 88–140 | 106 | ND–17 | 8.7 | RU |
| Color | 2021–2023 | UNITS | 15 | N/A | Yes | ND–10 | 5.0 | ND–5 | ND | OM |
| Iron | 2023 | ppb | 300 | N/A | Yes | N/A | ND | ND–42 | 19 | RU, IW |
| Manganese | 2023 | ppb | 50 | N/A | Yes | ND–40 | ND | ND–4.6 | 2.6 | RU |
| Specific conductance | 2021–2023 | µS/cm | 1600 | N/A | Yes | 1000–1200 | 1060 | 37–289 | 175 | IO |
| Sulfate | 2021–2023 | ppm | 500 | N/A | Yes | 81–160 | 115 | 1.2–36 | 17 | RU |
| Total dissolved solids | 2021–2023 | ppm | 1000 | N/A | Yes | 590–640 | 606 | ND–153 | 84 | RU |
| Turbidity (groundwater) | 2021–2023 | NTU | 5 | N/A | Yes | 0.34–4.2 | 2.2 | N/A | N/A | SO |
State-Regulated Contaminants with Notification Levels |
||||||||||
| Contaminants | Year Tested | Unit | NL | PHG (MCLG) | In Compliance | Groundwater | SFPUC Water | Source | ||
| Range | Average | Range | Average | |||||||
| Boron | 2018–2023 | ppm | 1 | N/A | Yes | N/A | ND | 0.02–0.07 | 0.04 | UR |
| Chlorate6 | 2021–2023 | ppb | 800 | N/A | Yes | N/A | ND | 30–749 | 141 | UR |
| Vanadium | 2023 | ppb | 50 | N/A | Yes | ND–5.4 | ND | N/A | N/A | UR |
Unregulated Compounds and Unregulated Contaminant Monitoring Rule (UCMR) |
||||||||||
| Constituents | Year Tested | Unit | NL | PHG (MCLG) | In Compliance | Groundwater | SFPUC Water | Source | ||
| Range | Average | Range | Average | |||||||
| Alkalinity (total) | 2021–2023 | ppm | N/A | N/A | N/A | 220–320 | 266 | 3.1–103 | 46 | UR |
| Calcium | 2021–2023 | ppm | N/A | N/A | N/A | 56–92 | 76 | 2.9–24 | 13 | UR |
| Haloacetic acids five | 2020 | ppb | N/A | N/A | N/A | 4.3–27 | 18 | N/A | N/A | UR |
| Haloacetic acids nine | 2020 | ppb | N/A | N/A | N/A | 6.8–28 | 19 | N/A | N/A | UR |
| Haloacetic acids six brominated | 2020 | ppb | N/A | N/A | N/A | ND–4.4 | ND | N/A | N/A | UR |
| Hardness (total) | 2021–2023 | ppm | N/A | N/A | N/A | 340–390 | 366 | 7.5–86 | 46 | UR |
| Hexavalent chromium | 2023 | ppb | N/A | N/A | N/A | N/A | ND | 0.11–0.35 | 0.23 | UR |
| Magnesium | 2021–2023 | ppm | N/A | N/A | N/A | 30–60 | 42 | 0.2–8.4 | 4.7 | UR |
| pH | 2023 | Units | N/A | N/A | N/A | 6.0–9.9 | 8.6 | 8.4–9.8 | 9.2 | UR |
| Potassium | 2021–2023 | ppm | N/A | N/A | N/A | 2.5–6.5 | 4.6 | 0.3–1.7 | 1 | UR |
| Quinoline | 2020 | ppt | N/A | N/A | N/A | ND–22 | ND | N/A | N/A | UR |
| Silica | 2023 | ppm | N/A | N/A | N/A | N/A | N/A | 4.4–9.4 | 6.2 | UR |
| Sodium | 2021–2023 | ppm | N/A | N/A | N/A | 73–89 | 81 | 2.7–20 | 14 | UR |
| Strontium | 2023 | ppb | N/A | N/A | N/A | N/A | N/A | 14–331 | 139 | UR |
1: Exceeds if routine and repeat samples are total coliform-positive and either is E. coli-positive, system fails to take repeat samples following E. coli-positive routine sample, or system fails to analyze total coliform-positive repeat sample for E. coli.
2: SFPUC supply data reported is from 2023. In 2023, SFPUC delivered water to our system.
3: Natural fluoride in the Hetch Hetchy source was ND. Elevated fluoride levels in raw water to the water treatment plants were attributed to the transfer of fluoridated Hetch Hetchy water into the local reservoirs. In 2023, the average fluoride level in raw water sources was 0.3 mg/L.
4: For surface water systems, the TT dictates that the turbidity level of the filtered water be less than or equal to 0.3 NTU in 95% of measurements taken each month and not exceed 1 NTU for more than one continuous hour. Sunol Valley Water Treatment Plant (SVWTP) had a turbidity value at 2.2 NTU and the treatment plant was shut down immediately. The turbidity value did not exceed the limit for more than one hour meeting the regulatory condition. Turbidity is a measurement of cloudiness of water. We monitor it because it is a good indicator of the effectiveness of our filtration system.
5: TOC is a precursor for disinfection byproduct formation. The TT requirement applies to the filtered water from the SVWTP only. In 2023, the range of the SVWTP effluent TOC levels were 0.6 ppm–3.3 ppm.
6: The detected chlorate in the treated water is a degradation product of sodium hypochlorite used by the San Francisco Regional Water System (SFRWS) for water disinfection.
Thank you
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