San Mateo 2018 Water Quality Report

Welcome

Girl holding water glassWe encourage you to review this annual water quality report, also called your Consumer Confidence Report, as it details any constituents detected in your water supply in 2018 and shows how your water compares to federal and state standards.

If you have any questions, please Contact Us. We are here to assist you.

Your Water System

Glass of water by a riverDistrict: Bayshore
System: San Mateo
System ID: #4110008

Cal Water has provided high-quality water utility services in the San Mateo area since 1931. Water for our customers is purchased from the San Francisco Public Utilities Commission (SFPUC). The San Mateo system has 18 storage tanks and 30 booster pumps.

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 ensure a reliable, high-quality supply.

If you have any questions, suggestions, or concerns, please contact our local Customer Center, either by phone at (650) 558-7800 or through the Contact Us page.

Protecting Our Watersheds

The SFPUC conducts watershed sanitary surveys for the Hetch Hetchy source annually and local water sources every five years. The last local sanitary survey was done in 2016. The SFPUC conducted a special watershed sanitary survey for the Upcountry Non-Hetch Hetchy Source (UNHHS) in 2015 as part of its drought response plan efforts. These surveys evaluated the sanitary condition, water quality, potential contamination sources, and results of watershed management activities, and were completed with support from partner agencies including the National Park Service and U.S. Forest Service.

These surveys identified wildlife, stock, and human activities as potential contamination sources. You may contact the San Francisco District office of the State Water Resources Control Board's (SWRCB) Division of Drinking Water (DDW) at (510) 620-3474 to review these activities.

We encourage customers to join us in our efforts to prevent water pollution and protect our most precious natural resource.

The Water Quality Lab

BeakerWater professionals collect samples from throughout the water system for testing at our state-of-the-art water quality laboratory, which is certified through the stringent Environmental Laboratory Accreditation Program (ELAP). Scientists, chemists, and microbiologists test the water for 318 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 each year 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.

Possible Contaminants

Water sprayAll 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 United States Environmental Protection Agency (EPA) Safe Drinking Water Hotline at (800) 426-4791

The sources of drinking water (both tap and bottled) 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 can pick up substances resulting from the presence of animals or human activity.

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 chemicals, which are byproducts of industrial processes and petroleum production, and can also come from gas stations, urban stormwater runoff, agricultural application, and septic systems.
  • Radioactive contaminants, which can be naturally occurring or the result of oil and gas production and mining activities.

In order to ensure that tap water is safe to drink, the EPA and DDW prescribe regulations that limit the amount of certain contaminants in water provided by public water systems. 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. 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

Colorful patternAs 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 ensure 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, but what about your home's plumbing? In California, lead in drinking water comes primarily from materials and components used for in-home plumbing (for example, lead solder used to join copper plumbing, and brass and other lead-containing fixtures).

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 an action level exceedance (AL). 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.

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. Cal Water is responsible for providing high-quality drinking water to our customers' meters, 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 by a lab. More information about lead in drinking water can be found on the Safe Drinking Water Hotline or at www.epa.gov/safewater/lead.

Results of our lead monitoring program, conducted in accordance with the Lead and Copper Rule, can be found in the 2018 Water Quality Table later in this document. 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.

Testing for Lead in Schools

The State of California now requires 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 lead limits. We have been working with school districts serving kindergarten through 12th grade to develop sampling plans, test samples, and conduct follow-up monitoring for corrective actions. We have published a summary of local school lead testing from the last year in this year's Water Quality report. For more information, please see our Testing for Lead in Schools web page.

Key Definitions

Rubber duckMaximum Contaminant Level (MCL): The highest level of a contaminant that is allowed in drinking water. Primary MCLs protect public health and are set as close to the PHGs (or MCLGs) as are economically and technologically feasible. Secondary MCLs (SMCLs) relate to the odor, taste, and appearance of drinking water.

In Compliance: Does not exceed any applicable primary MCL, secondary MCL, 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.

Regulatory Action Level (AL): The concentration of a contaminant which, if exceeded, triggers treatment or other required action by the water provider.

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 EPA.

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): A health-based advisory level for an unregulated contaminant in drinking water. It is used by DDW to provide guidance to drinking water systems.

Primary Drinking Water Standard (PDWS): MCLs and MRDLs 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's Office of Environmental Health Hazard Assessment without regard to cost or available detection and treatment technologies.

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

Table Introduction

Water dropsCal Water tests your water for more than 140 regulated contaminants and dozens of unregulated contaminants. This table lists only those contaminants that were detected.

In the table, water quality test results are divided into several major sections (as needed): "Primary Drinking Water Standards," "Secondary Drinking Water Standards," "State-Regulated 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.

A list of codes found in the "Source" column and their definitions can be found at the bottom of this page.

Water Quality Table

Primary Drinking Water Standards

Distribution System-Wide

SFPUC Supply1

 
Microbiological Year Tested Unit MCL PHG (MCLG) In Compliance Highest Monthly Range Average Source
Total coliform
(systems with >40 samples/month)
(total coliform rule)
2018 positive samples 5% (0) Yes 0.9 n/a EN
Giardia lamblia2 2018 cyst/L TT (0) Yes n/a 0–0.24 0.03 FE
Inorganic Chemicals Year Tested Unit MCL PHG (MCLG) In Compliance Range Average Range Average Source
Fluoride 2018 ppm 2.0 1 Yes n/a n/a ND–0.7 0.3 ER, FL
Lead and Copper Year Tested Unit AL PHG (MCLG) In Compliance 90th Percentile Samples > AL 90th Percentile Samples > AL Source
Copper 2016 ppm 1.3 0.3 Yes ND 0 of 31 n/a n/a IC, ER, WD
Lead 2016 ppb 15 0.2 Yes ND 0 of 31 n/a n/a IC, ER, IM
Schools that requested lead sampling in 2018: 6
Disinfection Byproducts Year Tested Unit MCL PHG (MCLG) In Compliance Range Highest Annual Average Range Highest Annual Average Source
Haloacetic acids 2018 ppb 60 n/a Yes 9.3–52 37 n/a n/a DI
Total trihalomethanes 2018 ppb 80 n/a Yes 22.2–45.9 39.3 n/a n/a DI
Disinfectants Year Tested Unit MRDL MRDLG In Compliance Range Average Range Average Source
Chloramine 2018 ppm 4 4 Yes 0.51–3.18 2.33 n/a n/a DS
Surface Water—Turbidity and TOC Year Tested Unit MCL PHG (MCLG) In Compliance Highest Level Lowest Monthly Percent Highest Level Lowest Monthly Percent Source
Turbidity (surface water not requiring filtration)3 2018 NTU 5 n/a Yes n/a n/a 1.8 n/a SO
Turbidity
(surface water requiring filtration)4
2018 NTU TT n/a Yes n/a n/a 0.07 99.96 VA
  Year Tested Unit MCL PHG (MCLG) In Compliance Range Average Range Average Source
Total organic carbon (TOC)5 2018 ppm TT n/a Yes n/a n/a 1.2–2.9 2.2 VA

Secondary Drinking Water Standards

Distribution System-Wide

SFPUC Supply

 
Inorganic Chemicals Year Tested Unit SMCL PHG (MCLG) In Compliance Range Average Range Average Source
Color 2018 Units 15 n/a Yes n/a n/a ND–7 ND OM
Turbidity 2018 Units 5 n/a Yes n/a n/a ND–0.3 0.1 SO
Total dissolved solids 2018 ppm 1000 n/a Yes n/a n/a ND–144 82 RL
Specific conductance 2018 µS/cm 1600 n/a Yes n/a n/a 29–221 154 SW, IN
Chloride 2018 ppm 500 n/a Yes n/a n/a ND–17 8.9 RL, SW
Sulfate 2018 ppm 500 n/a Yes n/a n/a 0.9–29 16 RL, IW

State-Regulated Contaminants with Notification Levels

Distribution System-Wide

SFPUC Supply

 
Chemical Year Tested Unit NL PHG (MCLG) In Compliance Range Average Range Average Source
Boron 2018 ppm 1 n/a Yes n/a n/a ND–0.10 ND UR
Chlorate 2018 ppb 800 n/a Yes n/a n/a 42–230 124 UR
Hexavalent chromium6 2018 ppb n/a n/a Yes n/a n/a 0.031–0.1 0.068 ER, EF

Unregulated Compounds

Distribution System-Wide

SFPUC Supply

 
Inorganic Chemicals Year Tested Unit MCL PHG (MCLG) In Compliance Range Average Range Average Source
Calcium 2018 ppm n/a n/a Yes n/a n/a 2.9–18 11 ER
Magnesium 2018 ppm n/a n/a Yes n/a n/a ND–6.2 4.0 ER
Strontium 2018 ppb n/a n/a Yes n/a n/a 12–199 99 ER
pH 2018 Units n/a n/a Yes n/a n/a 8.6–9.8 9.4 PH
Hardness 2018 ppm n/a n/a Yes n/a n/a 15–68 47 ER
Sodium 2018 ppm n/a n/a Yes n/a n/a 2.3–20 14 ER
Alkalinity (as CaCO3) 2018 ppm n/a n/a Yes n/a n/a ND–132 51 ER
Bromide 2018 ppb n/a n/a Yes n/a n/a ND–27 7 ER
Silica 2018 ppm n/a n/a Yes n/a n/a 2.8–7.1 5.0 ER
Potassium 2018 ppm n/a n/a Yes n/a n/a 0.2–1.0 0.6 ER

1 SFPUC supply data reported is from 2018. The years prior to 2018 reflect Cal Water data.

2 Giardia lamblia samples were collected from pretreated water. Giardia lamblia is inactivated through treatment technique.

3 The turbidity standard for unfiltered supplies is 5 NTU. Turbidity is a measure of cloudiness of water. We monitor it because it is a good indicator of water quality. High turbidity can hinder the effectiveness of disinfectants.

4 For surface water systems, the treatment technique dictates that the turbidity level of the filtered water be less than or equal to 0.2 NTU in 95% of measurements taken each month and not exceed 1 NTU at any time.

5 TOC has no health effects; however, TOC provides a medium for the formation of disinfection byproducts. These byproducts include trihalomethanes and haloacetic acids. The treatment technique dictates that a removal ratio of 1 or higher must be achieved. Drinking water containing these byproducts in excess of the MCL may lead to adverse health effects such as liver, kidney, or nervous system problems, and may lead to an increased risk of cancer. Concerns regarding disinfection byproducts are based upon exposure over many years.

6 The previous MCL of 0.010 mg/L (10 ppb) for hexavalent chromium was withdrawn on September 11, 2017, and there is currently no MCL in effect. The state recommends that any hexavalent chromium results above the detection limit of 1 ppb be reported.

Substance Sources

ASInternal corrosion of AC water mains
BDBiodegradation byproduct of TCE and PCE groundwater contamination
BHResidue of banned herbicide
BIResidue of banned insecticide
BNBanned nematocide that may still be present in soils due to runoff/leaching from former use on soybeans, cotton, vineyards, tomatoes, and tree fruit
BRResidue of banned insecticide and rodenticide
BTBanned nematocide that may still be present in soils due to runoff and leaching from grain and fruit crops
CFDischarge from industrial chemical factories
CPDischarge from chemical plants and other industrial activities
DCDischarge from industrial and agricultural chemical factories and dry cleaning facilities
DIByproduct of drinking water disinfection
DKDecay of natural and manmade deposits
DSDrinking water disinfectant added for treatment
EFDischarge from electroplating factories, leather tanneries, wood preservation, chemical synthesis, refractory production, and textile manufacturing facilities
ENNaturally present in the environment
ERErosion of natural deposits
EXExtraction and degreasing solvent; used in manufacture of pharmaceuticals, stone, clay and glass products; fumigant
FDDischarge from factories, dry cleaners, and auto shops (metal degreaser)
FEHuman and animal waste
FIFire retardants; ceramics; electronics; solder
FLWater additive that promotes strong teeth; discharge from fertilizer and aluminum factories
FMPrimary component of some fumigants
FRRunoff and leaching from fertilizer use; leaching from septic tanks and sewage
FSFuel solvent
FWManufacture of food wrappings
GPInternal corrosion of galvanized pipes; discharge from electroplating and industrial chemical factories and metal refineries; runoff from waste batteries and paint
HBRunoff/leaching from herbicide used on beans, peppers, corn, peanuts, rice, and ornamental grasses
HDRunoff from herbicide use for terrestrial and aquatic weeds; defoliant
HEHerbicide runoff
HPBreakdown of heptachlor
HRRunoff from herbicide used on row crops
HSRunoff from herbicide used on soybeans, vegetables, and fruits
HTRunoff from herbicide use for terrestrial and aquatic weeds
IADischarge from industrial and agricultural chemical factories; leaching from hazardous waste sites; used as cleaning and maintenance solvent, paint and varnish remover, and cleaning and degreasing agent; byproduct of production of other compounds and pesticides
ICInternal corrosion of household plumbing systems
IDIndustrial discharges
IFDischarge from industrial factories; degreasing solvent; propellant and refrigerant
ILRunoff/leaching from insecticide used on cattle, lumber, and gardens
IMDischarge from industrial manufacturers
INRunoff/leaching from insecticide used on cotton and cattle
IOSubstances that form ions when in water
ITRunoff/leaching from insecticide used on field crops, fruits, and ornamentals, especially apples, potatoes, and tomatoes
IVRunoff/leaching from insecticide used on fruits, vegetables, alfalfa, and livestock
IWIndustrial waste
LARunoff from landfills; discharge of waste chemicals
LELeaking underground storage tanks
MADischarge from metal refineries and agricultural chemical factories; byproduct of chlorination reactions in wastewater
MDDischarge from metal-degreasing sites and other factories
MFDischarge from metal factories
MRDischarge from metal refineries, coal-burning factories, and electrical, aerospace, and defense industries
MSDischarge from metal degreasing sites and other factories; dry cleaning solvent; refrigerant
MUMunicipal and industrial waste discharges
OCRunoff from orchards; glass and electronics production waste
ODDischarges of oil-drilling waste and from metal refineries
OMNaturally occurring organic materials
ORLeaching from ore-processing sites; discharge from electronics, glass, and drug factories
PCDischarge from petroleum and chemical factories
PDDischarge from plastics, dyes, and nylon factories; leaching from gas storage tanks and landfills
PGDischarge from petroleum, glass, and metal refineries; discharge from mines and chemical manufacturers; runoff from livestock lots (feed additive)
PHInherent characteristic of water
PIDischarge from pharmaceutical and chemical factories; insecticide
PRInorganic chemical used in solid rocket propellant, fireworks, explosives, flares, matches, and a variety of industries; usually gets into drinking water as a result of environmental contamination from historic aerospace or other industrial operations that used or use, store, or dispose of perchlorate and its salts
PTDischarge from petroleum refineries
PVLeaching from PVC piping; discharge from plastics factories; biodegradation byproduct of TCE and PCE groundwater contamination
RBDischarge from rubber and chemical factories; inert ingredient in pesticides
RCRunoff from herbicide used on row crops, range land, lawns, and aquatic weeds
RFDischarge from refineries and factories; runoff from landfills and cropland
RIRunoff/leaching from rice herbicide
RLRunoff/leaching from natural deposits
RPDischarge from rubber and plastic factories; leaching from landfills
RRRunoff from herbicide used on row crops and along railroad and highway rights-of-way
RSResidue from some surface water treatment processes
RTRunoff/leaching from nematocide used on croplands
RWRunoff from herbicide used on rights-of-way, and crops and landscape maintenance
SFLeaching of soil fumigant used on rice, alfalfa, and grape vineyards
SMDischarge from steel/metal, plastic, and fertilizer factories
SOSoil runoff
SPDischarge from steel and pulp mills and chrome plating
SWSeawater influence
TCDischarge from industrial and agricultural chemical factories; solvent used in production of TCE, pesticides, varnish, and lacquers
TXDischarge from textile-finishing factories
UNUnderground gas tank leaks
VAVarious natural and manmade sources
WDLeaching from wood preservatives
WIEmissions from waste incineration and other combustion
WPDischarge from wood preserving factories, cotton, and other insecticidal/herbicidal uses
WSLeaching from linings of water storage tanks and distribution mains
URUnregulated constituents with no source listed and that do not have standardized “source of substance” language

Thank You

Sunrise over waterA full-color, printable version of this report in PDF format is also available.

If you have any questions about your water quality table, please Contact Us.