San Antonio Water Quality by Zone: What the 2026 Public Data Shows for Each Service Area

How hard is San Antonio water?

Water hardness is measured in grains per gallon (GPG). The U.S. Geological Survey defines hard water as 7 to 10.5 GPG and very hard as anything above 10.5 GPG (USGS Water Science School, usgs.gov/special-topics/water-science-school/science/hardness-water). San Antonio falls well into the very hard category across most of its distribution system. San Antonio Water System reports a system-wide hardness range of 15 to 22 GPG in its 2023 Consumer Confidence Report (saws.org/water-quality/consumer-confidence-reports/). That published range is a service-zone average. Zone-to-zone variation within the SAWS footprint and differences between SAWS and the surrounding independent utilities mean that the actual hardness at a specific tap depends on which source water your address receives on any given day.

The Edwards Aquifer drives the hardness. As groundwater filters through limestone formations over thousands of years, it dissolves calcium and magnesium, the two minerals that define hard water. The deeper the flow path through the limestone, the harder the water that emerges at production wellheads. The Edwards Aquifer itself typically yields water in the 15 to 20 GPG range depending on the specific wellfield and formation depth.

Seasonal blending shifts the numbers. SAWS supplements Edwards Aquifer supply with Canyon Lake surface water, which averages closer to 10 to 14 GPG before treatment. During Stage 2 drought restrictions, SAWS pulls more heavily from Canyon Lake and hardness in some distribution zones temporarily drops by 3 to 5 GPG. When the aquifer is the dominant source in wetter periods, hardness climbs back toward the high end of the published range. A water softener sized to a seasonal low reading can undersoften during dry August conditions when the Edwards blend percentage increases.

How does water quality differ across the San Antonio metro?

The communities True H2O serves fall into distinct water quality zones based on which utility and which source aquifer supplies their tap. Understanding the zone is the first step in choosing the right treatment system and sizing it correctly.

San Antonio city water (SAWS service area, including Converse and Universal City): SAWS customers receive Edwards Aquifer and Canyon Lake blended water at 15 to 22 GPG. The most common secondary concerns are trihalomethanes and haloacetic acids from surface water blending and chloramine, which SAWS uses as its primary disinfectant. Hardness is the dominant driver of treatment needs for the vast majority of SAWS customers. Converse and Universal City fall within the SAWS service footprint and receive the same very hard water profile as central San Antonio. Verify current hardness figures at saws.org before making any treatment decisions.

Schertz and Cibolo: These communities receive water through the Schertz-Seguin Local Government Corporation (SSLGC), which delivers Guadalupe-Blanco River Authority water sourced from Canyon Lake and the Guadalupe River. SSLGC water typically tests in the 16 to 22 GPG range. Total dissolved solids from the surface-water blend are a secondary concern in some zones. Verify current hardness and water quality figures directly with SSLGC (sslgc.org) for accurate treatment sizing at a Schertz or Cibolo address.

New Braunfels: The city of New Braunfels receives water primarily from the Guadalupe-Blanco River Authority, drawing from Canyon Lake and Comal Springs. GBRA source water in this area typically runs 14 to 20 GPG. Seasonal taste-and-odor events tied to algae activity in Canyon Lake reservoir are more common in New Braunfels than in Edwards Aquifer-dominant zones closer to San Antonio. Verify hardness figures with the New Braunfels Utilities annual water quality report (nbutexas.com) for your specific address.

Boerne and Helotes (private well customers): Communities in Kendall County and the northwest Bexar County hill country include significant well-served populations not connected to SAWS or other municipal systems. Private wells in this area draw from the Trinity Aquifer or from Edwards Aquifer wells in its Kendall County margin. Trinity Aquifer water in this region can test 20 to 28 GPG, with occasional elevated radium, iron, and sulphur concentrations not present in SAWS treated supply (Edwards Aquifer Authority water quality resources, edwardsaquifer.org). Well water is not subject to routine utility monitoring. Annual testing by a Texas Commission on Environmental Quality certified laboratory is the only reliable way to know what is actually in a specific well.

What contaminants does San Antonio water contain beyond hardness?

Hardness is the most common driver of water treatment decisions in the San Antonio area, but SAWS water contains several additional contaminants the annual Consumer Confidence Report tracks and discloses. None exceeded EPA maximum contaminant levels in 2023, but understanding them helps homeowners make informed treatment choices.

Radium-226 and radium-228 (combined) were detected at up to 2.9 picoCuries per liter (pCi/L) in the SAWS 2023 CCR. The EPA maximum contaminant level is 5 pCi/L, so SAWS water is within the federal legal limit. Edwards Aquifer water in limestone formations can concentrate radionuclides. The detected level is below the MCL but above zero. Private wells in Kendall County and the Edwards Fault Zone north of San Antonio should be tested individually for radium, as concentrations in well water can differ significantly from SAWS treated supply (SAWS 2023 Consumer Confidence Report, saws.org/water-quality/consumer-confidence-reports/).

Total trihalomethanes (TTHMs): These disinfection byproducts form when chlorine or chloramine reacts with organic matter in surface water. SAWS reported a 2023 annual average of 32 parts per billion against a federal MCL of 80 ppb. TTHM levels increase during months when Canyon Lake surface water makes up a larger share of the blend. Customers in zones supplied by more surface water sometimes notice seasonal changes in taste. Whole-home carbon prefiltration reduces TTHM load before softening.

Haloacetic acids (HAA5s): A second class of chlorination byproduct. SAWS reported a 2023 annual average of 14 ppb against a 60 ppb MCL. Like TTHMs, HAA5s correlate with surface water content in the blend and are reduced by carbon filtration (SAWS 2023 CCR, saws.org).

Fluoride: Added at 0.7 milligrams per liter per CDC dental health recommendations, which SAWS meets. Some customers prefer to remove fluoride from drinking water via undersink reverse osmosis. Fluoride is not removed by standard carbon filters or ion exchange water softeners.

For private well users in the True H2O service area: iron staining, sulphur odor, and elevated bacteria are the most commonly reported issues in Kendall County and well-served areas around Boerne and Helotes. The Texas Commission on Environmental Quality recommends annual testing for bacteria and nitrates as a minimum for private well owners, with a broader panel every three to five years (tceq.texas.gov). Well water is not subject to the regulatory monitoring that applies to SAWS customers, so homeowner-initiated testing is the only way to detect problems early.

Is San Antonio water safe to drink?

Yes. SAWS met all Safe Drinking Water Act primary standards in 2023 with no maximum contaminant level violations (SAWS 2023 Consumer Confidence Report, saws.org). Safe under federal law means every regulated contaminant is below the concentration at which the EPA projects a lifetime cancer risk above 1 in 10,000. That is a public health threshold, not a zero-risk standard.

For most San Antonio households on SAWS water, the practical concerns are comfort and appliance longevity rather than acute health risk. Water testing at 15 to 22 GPG leaves mineral deposits on showerheads within weeks, reduces soap lather efficiency, and shortens water heater element life by 22 to 30 percent compared to soft water environments (U.S. Department of Energy, energy.gov/energysaver). Those are quality-of-life and maintenance cost issues. They are not safety issues, but they are the primary reasons most San Antonio homeowners seek water treatment.

Private well users face a different situation. Well water in Texas is not regulated or monitored by any public utility unless a violation is specifically investigated. Coliform bacteria contamination in well water is the highest-priority safety concern and requires immediate treatment if detected. Nitrates above 10 milligrams per liter pose a health risk to infants. The TCEQ recommends annual bacteria and nitrate testing for all private well owners as a minimum safety check (tceq.texas.gov/water/utilities/local-water-supply/drinking-water-data.html).

What water treatment does each San Antonio service area need?

The right system depends on water source, what an in-home test finds for hardness and secondary parameters, and household priorities. That said, clear patterns emerge by zone across the True H2O service area.

SAWS city water in San Antonio, Converse, and Universal City: Hardness at 15 to 22 GPG makes a whole-home ion exchange water softener the first-priority treatment for most households. A properly sized softener removes calcium and magnesium before water reaches any fixture or appliance. For customers concerned about chloramine taste or TTHM exposure from surface water blending, a carbon prefiltration stage added downstream of the softener addresses both. An undersink reverse osmosis unit at the kitchen tap removes fluoride, residual nitrates, and dissolved solids from drinking and cooking water.

Schertz and Cibolo customers on SSLGC water: The hardness profile is similar to SAWS at 16 to 22 GPG and the treatment approach follows the same priority: softener first. Total dissolved solids from the Guadalupe-Blanco surface-water blend may support adding carbon prefiltration for taste. Verify hardness with SSLGC before sizing the softener, as the blend from GBRA can shift seasonally.

New Braunfels customers on New Braunfels Utilities water: GBRA source water at 14 to 20 GPG still warrants a whole-home softener for most households. The lower end of this range means some New Braunfels homes may need a slightly smaller softener capacity than a central San Antonio address at the same household size. Seasonal algae-related taste events are best addressed with a carbon prefiltration stage that removes the organic compounds responsible for taste-and-odor episodes in summer.

Boerne and Helotes customers on private wells: Well water from the Trinity Aquifer in this area commonly presents iron, sulphur, and occasionally elevated radium alongside high hardness. Iron and sulphur require a dedicated oxidation and filtration stage installed before the softener. Running iron-laden water through a softener resin bed fouls the resin and shortens system life. Point-of-use reverse osmosis at the kitchen sink addresses radium at the drinking tap if a well test indicates elevated levels. Whole-house radium removal, when warranted, requires specific ion exchange media. A comprehensive certified lab test should always precede any equipment recommendation for well water customers.

How does the Edwards Aquifer affect San Antonio water quality?

The Edwards Aquifer is a karst limestone formation spanning roughly 3,000 square miles beneath central Texas. It recharges during rainfall events over the Hill Country recharge zone west and north of San Antonio and serves as the primary drinking water source for more than 2 million people in the region (Edwards Aquifer Authority, edwardsaquifer.org/the-aquifer/). SAWS typically draws between 60 and 80 percent of its supply from the aquifer depending on season and aquifer level.

Limestone geology explains the hardness. As groundwater percolates through calcium carbonate rock, it dissolves calcium and magnesium ions. The deeper and longer the flow path through the limestone, the harder the water at the wellhead. Drought years lower the aquifer level, which can concentrate minerals by reducing dilution from recent recharge and push SAWS toward a higher aquifer-percentage blend. That is why San Antonio's hardest-water service calls tend to cluster in dry late-summer periods rather than in wet winter months.

The Edwards Aquifer Authority regulates pumping through a permit cap system set partly by federal court order to protect downstream spring flows at Comal Springs in New Braunfels and San Marcos Springs (Edwards Aquifer Authority, edwardsaquifer.org/water-management/). During Stage 2 drought restrictions, SAWS must reduce Edwards pumping and replace the volume with Canyon Lake surface water. This surface water carries lower hardness but higher organic content. Customers in zones that primarily receive Edwards Aquifer water sometimes notice the blend shift as a change in taste and a temporary softening at the tap.

The aquifer's variability reinforces one practical point for homeowners: a softener sized to the published service-zone average rather than a reading at your specific tap can undersoften during dry months and regenerate more frequently than necessary in wet ones. A calibrated in-home hardness test gives you the actual reading at your address on the day of the test, which is the baseline for accurate softener sizing. True H2O provides free in-home water testing across the San Antonio metro. Call (210) 726-6895 to schedule.

What San Antonio homeowners ask most about their water quality

Why is there white scale on my fixtures and dishes? Calcium carbonate deposits from hard water. At 15 to 22 GPG, visible scale appears on faucets and showerheads within weeks of installation. A whole-home ion exchange softener stops new scale from forming at every tap. Existing buildup dissolves gradually as soft water passes through the home over weeks. Soaking aerators in white vinegar accelerates scale removal on individual fixtures.

Why does my water heater seem to fail early? Limescale accumulates on electric heating elements, forcing them to run longer to heat the same volume of water. The U.S. Department of Energy estimates that hard water can reduce water heater efficiency by 22 to 30 percent and cut service life well below the expected 10 to 12 years (energy.gov/energysaver). In San Antonio's very hard water environment, an unprotected electric water heater commonly shows heating element failure before the 8-year mark.

Is San Antonio tap water safe for my family? SAWS municipal water met all Safe Drinking Water Act primary standards in 2023 with no MCL violations. The water is federally safe for all normal household uses. For private well users in Boerne, Helotes, and rural areas around the metro: well water should be tested annually by a TCEQ-certified laboratory. There is no government agency monitoring the quality of private well water in Texas on an ongoing basis.

How much salt does a water softener use? A properly sized softener for San Antonio's hardness range uses roughly 6 to 10 pounds of salt per regeneration cycle. A household of four at average water usage typically regenerates the softener every 5 to 7 days. Actual salt consumption depends on the hardness reading at your specific address, household size, and whether the softener uses demand-initiated or timer-based regeneration. Demand-initiated softeners use less salt by regenerating only when the resin is near capacity rather than on a fixed schedule.

Will soft water taste salty? Ion exchange softeners replace calcium and magnesium with sodium ions during the exchange process. At typical regeneration levels for San Antonio water, the sodium added stays below the 200 milligrams per liter threshold most people detect by taste. Individuals on sodium-restricted diets should pair a softener with an undersink reverse osmosis unit for drinking water, as RO removes the exchanged sodium along with other dissolved minerals.

True H2O provides free in-home water testing across San Antonio, New Braunfels, Schertz, Cibolo, Boerne, Helotes, Converse, and Universal City. A written no-obligation recommendation follows every test. Call (210) 726-6895 or visit the water testing page to schedule your test.