San Antonio
TX

Is San Antonio, TX Tap Water Safe to Drink?

San Antonio, TX tap water has a significant concern: lithium levels detected in recent EPA testing reached 133 µg/L, well above the 10 µg/L EPA drinking water standard, and every ZIP code in the dataset is affected. Several PFAS compounds were also detected, though at or near the reporting threshold. If you are in a sensitive group, a certified filter is a practical precaution.

19Water systems
59ZIP codes
100%ZIPs above EPA guideline
Metro areaSan Antonio-New Braunfels, TX
Latest data2025-11-12

Where Does San Antonio Get Its Water?

San Antonio, TX draws its drinking water from a combination of groundwater and surface water sources serving Bexar County and surrounding communities. The primary utility is San Antonio Water System, one of the largest municipal water providers in Texas, which supplies the majority of residents across the city.

Several smaller water systems also serve portions of the San Antonio area, including Alamo Heights, Leon Valley, Live Oak, Kirby, Elmendorf, Windcrest, East Central Special Utility District, and Atascosa Rural Water Supply Corporation. Joint Base San Antonio operates its own water systems for military installations at Medina and the Sam Houston area.

The San Antonio Water System draws from the Edwards Aquifer, a major regional groundwater source, and supplements supply through surface water and purchased water interconnections. This layered approach helps the region manage demand and drought conditions across a broad service area.

How Is San Antonio Tap Water Treated?

Water treatment across San Antonio's utilities includes a range of processes. Coagulation and conventional filtration are used at surface water facilities, while granular activated carbon helps reduce organic compounds and certain chemical contaminants. Some systems also use additional adsorption and disinfection steps tailored to their specific source water.

Disinfection is carried out using free chlorine and chloramines, with some systems using a combination of approaches. These disinfectants kill bacteria and viruses that could otherwise make water unsafe to drink, and a residual disinfectant level is maintained in pipes all the way to your tap.

Groundwater from the Edwards Aquifer requires less treatment than surface water, but utilities still apply disinfection and monitor for naturally occurring minerals. The aquifer's geology contributes to the elevated lithium levels seen throughout the region, which treatment processes do not fully remove.

What's in San Antonio Tap Water?

The main concern in San Antonio tap water is lithium. EPA testing found a peak concentration of 133 µg/L, which is more than 13 times the 10 µg/L EPA drinking water standard. Detections were recorded across all 59 ZIP codes in the dataset, making this a citywide issue rather than one isolated to a specific neighborhood.

Several PFAS compounds were also detected, including PFTrDA, 8:2 FTS, 6:2 FTS, and HFPO-DA. Each was detected at or at the limit of reporting sensitivity, around 0.005 to 0.007 µg/L, and none of these specific compounds exceeded an EPA guideline in this dataset. Their presence is still worth noting given ongoing research into PFAS health effects.

Lithium occurs naturally in groundwater drawn from certain rock formations, which is consistent with the Edwards Aquifer geology underlying much of San Antonio's water supply. PFAS compounds can enter water from a variety of environmental sources and are monitored nationally as part of recent EPA testing programs.

ContaminantPeak detectedEPA guidelineZIPs detectedStatus
lithium 133 µg/L 10 µg/L 59 ZIPs Above guideline
PFTrDA 0.007 µg/L — 0 ZIPs Within guideline
8:2 FTS 0.005 µg/L — 0 ZIPs Within guideline
6:2 FTS 0.005 µg/L — 0 ZIPs Within guideline
HFPO-DA 0.005 µg/L — 0 ZIPs Within guideline

Health Risk Profile for San Antonio

Lithium at 133 µg/L is more than 13 times the EPA's 10 µg/L drinking water standard. At elevated concentrations, lithium can affect thyroid and kidney function and has been studied for neurological effects. The EPA standard exists because chronic exposure above that level is considered a health concern for regular tap water consumers.

Infants, pregnant individuals, and people with kidney or thyroid conditions face a higher risk from elevated lithium because their bodies are less able to tolerate fluctuations in mineral intake. Bottle-fed infants are particularly vulnerable since formula mixed with tap water concentrates exposure. If you fall into one of these groups, filtering your water or using an alternative source is worth considering.

For lithium, a reverse osmosis filter certified to NSF/ANSI 58 is the most effective home option; reverse osmosis removes a broad range of dissolved minerals including lithium. For the PFAS compounds detected, look for a filter also certified to NSF/ANSI P473, the independent third-party standard that confirms a filter reduces PFAS in drinking water. NSF/ANSI certification means an independent organization has verified the performance claim on the box.

The PFAS levels detected here are at or near the minimum concentration the testing equipment can reliably measure, so they represent a lower-level concern than the lithium findings. Science on low-level PFAS exposure is still evolving, and the EPA continues to update guidance as research develops.

Best Broad-Spectrum Filters for This Water Profile

This city profile includes PFAS detections, chlorine disinfection, and other dissolved contaminants. Reverse osmosis (RO) systems certified under NSF/ANSI 58 provide broad reduction coverage; for PFAS specifically, confirm NSF/ANSI P473 or equivalent PFAS reduction certification.

Waterdrop G3P600 Reverse Osmosis System
Under-sink RO system

8-stage tankless RO system certified to NSF/ANSI 58, reduces 1,000+ contaminants including PFAS, lead, arsenic, fluoride, and nitrates.

See recommendations matched to your exact address: choose your ZIP code below.

Frequently Asked Questions about San Antonio Tap Water

Is San Antonio tap water safe to drink?

San Antonio tap water has a notable concern. Lithium was detected at up to 133 µg/L in recent EPA testing, more than 13 times the EPA's 10 µg/L standard, and this applies across all ZIP codes in the dataset. Several PFAS compounds were also detected at low levels. For most healthy adults the short-term risk may be limited, but sensitive groups should consider a certified filter.

What contaminants are in San Antonio tap water?

The top concern is lithium, detected at a peak of 133 µg/L against an EPA standard of 10 µg/L. Several PFAS compounds including PFTrDA, 8:2 FTS, 6:2 FTS, and HFPO-DA were also detected, each at roughly 0.005 to 0.007 µg/L, at or near the reporting threshold and below current EPA guidelines for those specific compounds. Disinfectants including free chlorine and chloramines are also present as intended.

Where does San Antonio get its drinking water?

Most of San Antonio's water comes from the Edwards Aquifer, a regional groundwater source, supplied primarily through San Antonio Water System. Smaller utilities serving parts of the area include Alamo Heights, Leon Valley, Live Oak, Kirby, and Atascosa Rural Water Supply Corporation, among others. Surface water and purchased water interconnections supplement supply during high-demand periods.

Do I need a water filter in San Antonio?

Given the elevated lithium levels, a reverse osmosis filter certified to NSF/ANSI 58 is a practical choice. It removes dissolved minerals including lithium effectively. For the PFAS compounds detected, adding NSF/ANSI P473 certification to your filter criteria covers those as well. NSF/ANSI is an independent third-party label you can check on the filter's packaging or the manufacturer's website.

How often is San Antonio tap water tested?

San Antonio's utilities are required to monitor water quality regularly under federal and state rules, with results reported to the EPA and published in annual Consumer Confidence Reports. The data shown here comes from EPA testing with the most recent samples dated November 2025. Utilities test for dozens of contaminants on schedules set by the EPA based on the type of source water and system size.

What is the best water filter for San Antonio?

A reverse osmosis system certified to NSF/ANSI 58 is the best match for San Antonio's contaminant profile, particularly for reducing lithium. Make sure it also carries NSF/ANSI P473 certification to address the PFAS compounds detected. Pitcher or faucet filters with NSF/ANSI 42 certification handle taste and chlorine but are not rated to remove lithium or PFAS at meaningful levels.

Tap water reports by ZIP in San Antonio

Water utilities serving San Antonio, TX

Service area boundaries are approximate and based on state filings or modeled estimates. Contact your utility to confirm exact service at a specific address.

Modeled boundaries are shown with a dashed outline.

Also covers / overlaps with