San Antonio Water System

Source of Drinking Water

The sources of drinking water (both tap water 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 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, which may come from sewage treatment plants, septic systems, agriculture, livestock operations, and wildlife. SAWS is required to sample 390 sites in the distribution system for bacteria each month, and no E. coli positives were found in our drinking water in 2023.

Inorganic contaminants, such as salts and metals, which can be naturally occurring or result from urban storm water 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 storm water runoff, and residential uses.

Organic chemical contaminants, including synthetic and volatile organic chemicals, which are by-products of industrial processes and petroleum production, and can also come from gas stations, urban storm water runoff, and septic systems.

Radioactive contaminants, which can be naturally occurring or be the result of oil and gas production and mining activities.

Where Do We Get Our Drinking Water?

The source of SAWS drinking water originated as groundwater from the Edwards, Carrizo, Simsboro, Trinity and Wilcox aquifers, and in some areas, surface water from Canyon Lake. No Source Water Susceptibility Assessment for your drinking water source(s) has been conducted by the Texas Commission on Environmental Quality for your water system. This information describes the susceptibility and types of constituents that may come into contact with your drinking water source based on human activities and natural conditions. SAWS purchases water from GBRA Western Canyon Water Supply, Oliver Ranch, Schertz Sequin Local Government Corporation, Water Exploration Stein Roger Well Field and Central Texas Regional WSC. For more information on source water assessments and protection efforts, please contact us.

The information contained in the assessment allows us to better focus our source water protection strategies. Some of this source water assessment information is available on Texas Drinking Water Watch.

All Drinking Water May Contain Contaminants

When drinking water meets federal standards, there may not be any health benefits to purchasing bottled water or point of use devices. 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’s Safe Drinking Water Hotline (800-426-4791).

Secondary Constituents

Many constituents (such as calcium, sodium, or iron), which are found in drinking water, can cause taste, color, and odor problems. The taste and odor constituents are called secondary constituents and are regulated by the State of Texas, not the EPA. These constituents are not causes for health concern. Therefore, secondaries are not required to be reported in this document, but they may affect the appearance and taste of your water. The secondary constituents results are available for this System on Texas Drinking Water Watch.

Health Information About Lead

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. San Antonio Water System 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 two 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.

Special Notice

You may be more vulnerable than the general population to certain microbial contaminants, such as Cryptosporidium, in drinking water. Infants, some elderly or immuno-compromised such as those undergoing chemotherapy for cancer; those who have undergone organ transplants; those who are undergoing treatment with steroids; and people with HIV/AIDS or other immune system disorders can be particularly at risk from infections. You should seek advice about drinking water from your physician or health care provider. Additional guidelines on appropriate means to lessen the risk of infection by Cryptosporidium are available from the Safe Drinking Water Hotline at 800-426-4791.

Violations

The SAWS main system received no violations in 2023.

How To Read Your Water Quality Report

Coliform Bacteria
Monitored in the Distribution System

Parameter/ Substance	Date Sampled	MCLG	Total Coliform MCL	Highest No. of Positive	Fecal Coliform or E. Coli or Fecal MCL	Total No. of Positive E. Coli or Fecal	Violation	Likely Source of Contamination
Coliform Bacteria	2023	0	5% of monthly samples are positive	0.5	A routine sample and a repeat sample are total coliform positive, and one is also fecal coliform or E. coli positive.	0	No	Naturally present in the environment

Lead And Copper
Monitoring Done at Customers’ Taps

Parameter/ Substance	Date Sampled	MCLG	AL	90th Percentile	Number of Sites Over AL	Units	Violation	Likely Source of Contamination
Copper	2021	1.3	1.3	0.206	0	ppm	No	Corrosion of household plumbing systems; erosion of natural deposits; leaching from wood preservatives
Lead	2021	0	15	2.25	0	ppb	No	Corrosion of household plumbing systems; erosion of natural deposits

Disinfectants And Disinfection By-products
Monitored in the Distribution System

Parameter/ Substance	Collection Date	Highest Level Detected	Range of Individual Samples	MCLG	MCL	Units	Violation	Likely Source of Contamination
Haloacetic Acids (HAA5)*	2023	7.68	0 – 19.4	NA	60	ppb	No	By-product of drinking water disinfection
Total Trihalomethanes (TTHMs)*	2023	42.2	0 – 52.9	NA	80	ppb	No	By-product of drinking water disinfection

*The value in the Highest Locational Running Annual Average column is the highest average of all TTHM and HAA5 sample results collected at a location over a year.

Inorganic Contaminants
Monitored at the Water Plants

Parameter/ Substance	Collection Date	Highest Level Detected	Concentration Range Found	MCLG	MCL	Units	Violation	Likely Source of Contamination
Barium	2023	0.0918	0.0395 – 0.0918	2	2	ppm	No	Discharge from drilling wastes; discharge from metal refineries; erosion of natural deposits
Fluoride	2023	3.21	0.15 – 3.31	4	4	ppm	No	Erosion of natural deposits; water additive which promotes strong teeth; discharge from fertilizer and aluminum plants
Nitrate (measured as Nitrogen)	2023	2.51	0 – 2.51	10	10	ppm	No	Runoff from fertilizer use; leaching from septic tanks, sewage; erosion of natural deposits
Selenium	2023	4.2	0 – 4.2	50	50	ppb	No	Discharge from petroleum and metal refineries; erosion of natural deposits; discharge from mines

Radioactive Contaminants
Monitored at the Water Plants

Parameter/ Substance	Collection Date	Highest Level Detected	Concentration Range Found	MCLG	MCL	Units	Violation	Likely Source of Contamination
Beta/Photon Emitters	2023	5.5	0– 5.5	0	50	pCi/L**	No	Decay of man-made and natural deposits
Combined Radium 226/228	2023	1.82	1.33 – 1.82	0	5	pCi/L	No	Erosion of natural deposits
Gross Alpha Excluding Radon and Uranium	2023	6.2	0 – 6.2	0	15	pCi/L	No	Erosion of natural deposits

**The EPA considers 50 pCi/L to be the level of concern for beta particles.

Residual Disinfectant Level
Monitored in the Distribution System

Parameter/ Substance	Year	Average Level	Range of Levels Detected	MRDL	MRDLG	Units	Violation	Likely Source of Contamination
Chlorine Residual, Free	2023	1.45	2.50	4	4	ppm	No	Water additive used to control microbes

UCMR 5 Results
Unregulated Contaminants 

Parameter/ Substance	Collection Date	Average Level	Range of Levels Detected	MRL	Health-Based Reference Concentration	Units	Health Information Summary
Lithium	2023	12.82	9 – 25.5	9	10	ppb	This data is part of UCMR 5 results in relation to minimum reporting levels and available non-regulatory health-based reference concentrations.
PFPeA (Perfluoropentanoic Acid)	2023	0.0032	0.0032 – 0.0032	0.003	Not Set	ppb	This data is part of UCMR 5 results in relation to minimum reporting levels and available non-regulatory health-based reference concentrations.
PFBA (Perfluorobutanoic Acid)	2023	0.0075	0.006 – 0.0092	0.005	Not Set	ppb	This data is part of UCMR 5 results in relation to minimum reporting levels and available non-regulatory health-based reference concentrations.

Results From Systems We Purchased Water From:
GBRA Western Canyon Water Supply

Turbidity**	Level Detected	Limit (Treatment Technique)	Violation	Likely Source of Contamination
Highest Single Measurement	0.21 NTU	1 NTU	No	Soil runoff
Lowest Monthly % Meeting Limit	100%	0.3 NTU	No	Soil runoff

** Turbidity is a measurement of the cloudiness of the water caused by suspended particles. Turbidity is monitored because it is a good indicator of water quality and the effectiveness of filtration systems and disinfectants.

Central Texas Regional WSC
Disinfectants And Disinfection By-Products

Parameter/ Substance	Collection Date	Highest Level Detected	Range of Individual Samples	MCLG	MCL	Units	Violation	Likely Source of Contamination
Haloacetic Acids (HAA5)*	2023	1.7	1.7 – 1.7	NA	60	ppb	No	By-product of drinking water disinfection
Total Trihalomethanes (TTHMs)*	2023	18.1	18.1 – 18.1	NA	80	ppb	No	By-product of drinking water disinfection

*The value in the Highest Level or Average Detected column is the highest average of all HAA5 sample results collected at a location over a year.

Inorganic Contaminants

Parameter/ Substance	Collection Date	Highest Level Detected	Concentration Range Found	MCLG	MCL	Units	Violation	Likely Source of Contamination
Barium	2023	0.0945	0.0945 – 0.0945	2	2	ppm	No	Discharge from drilling wastes; discharge from metal refineries; erosion of natural deposits
Fluoride	2023	0.21	0.21 – 0.21	4	4	ppm	No	Erosion of natural deposits; water additive which promotes strong teeth; discharge from fertilizer and aluminum plants

Radioactive Contaminants

Parameter/ Substance	Collection Date	Highest Level Detected	Concentration Range Found	MCLG	MCL	Units	Violation	Likely Source of Contamination
Gross Alpha Excluding Radon and Uranium	2023	3.9	3.9 – 3.9	0	15	pCi/L	No	Erosion of natural deposits

Residual Disinfectant Level

Parameter/ Substance	Year	Average Level	Range of Levels Detected	MRDL	MRDLG	Units	Violation	Likely Source of Contamination
Chlorine Residual, Free	2023	1.47	1.19 – 1.97	4	4	ppm	No	Water additive used to control microbes

Definitions

The preceding tables contain scientific terms and measures, some of which may require explanation.

AL (Action Level) – The concentration of a contaminant which, if exceeded, triggers treatment or other requirements which a water system must follow.
ALG (Action Level Goal) – The level of a contaminant in drinking water below which there is no known or expected risk to health. ALGs allow for a margin of safety.
Avg (Average) – Regulatory compliance with some MCLs are based on a running annual average of monthly samples.
Level 1 Assessment – A study of the water system to identify potential problems and determine (if possible) why total coliform bacteria have been found in our water system.
Level 2 Assessment – 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 our water system on multiple occasions.
MCL (Maximum Contaminant Level) – The highest level of a contaminant that is allowed in drinking water. MCLs are set as close to the MCLGs as feasible using the best available treatment technology.
MCLG (Maximum Contaminant Level Goal) – The level of a contaminant in drinking water below which there is no known or expected risk to health. MCLGs allow for a margin of safety.
MFL– Million fibers per liter (a measure of asbestos)
MRDL (Maximum Residual Disinfectant Level) – 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.
MRDLG (Maximum Residual Disinfectant Level Goal) – 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.
mrem – Millirems per year (a measure of radiation absorbed by the body)
MRL (Minimum Reporting Levels) – The lowest concentrations laboratories may report to the EPA. MRLs are determined using data from multiple laboratories that participate in the EPA’s MRL-setting studies and are not associated with contaminant health effects information. The EPA establishes MRLs to ensure consistency in the quality of the information reported to the agency.
NA – Not applicable
ND – Not detected
NTU – Nephelometric turbidity units (a measure of turbidity)
pCi/L – Picocuries per liter (a measure of radioactivity)
ppb – Parts per billion or micograms per liter (μg/L) or one ounce in 7,350,000 gallons of water
ppm – Parts per million or milligrams per liter (mg/L) or one ounce in 7,350 gallons of water
ppq – Parts per quadrillion or picograms per liter (pg/L)
ppt – Parts per trillion or nanograms per liter (ng/L)
TT (Treatment Technique) – A required process intended to reduce the level of a contaminant in drinking water
μmhos/cm – Micromhos per centimeter (a measure of conductivity)

State Water Loss Audit

In the water loss audit submitted to the Texas Water Development Board for the period of January through December 2023, San Antonio Water System (all San Antonio Water System PWSs) lost an estimated combined total of 21,285,680,159 gallons of water through main breaks, leaks, inaccurate customer metering, theft and other causes.