Water Quality in San Antonio, TX

San Antonio's water has very hard water (240 PPM). A water softener is recommended to protect plumbing and appliances. Read below for a full breakdown.

SAWS · Source: Edwards Aquifer · Serves 1,547,253 residents

240
Hardness (PPM)
380
TDS (PPM)
1.5
Chlorine (mg/L)
3
PFAS (ppt)
1
Lead (ppb)
240 PPM 0 400 Very Hard
CONTAMINANT LEVELS Hardness 240 PPM TDS 380 PPM PFAS 3 ppt Lead 1 ppb Chlorine 1.5 mg/L Nitrate 4 mg/L

Hardness Scale: Where San Antonio Falls

Soft 060120180250400+
Very hard water (limestone aquifer)High TDS

What San Antonio's Water Means for Your Home

San Antonio residents deal with some of the hardest municipal water in the country. At 240 PPM (undefined grains per gallon), the water contains high concentrations of dissolved calcium and magnesium picked up from underground limestone and mineral formations. This is not a safety issue. The minerals are safe to consume. But they create real, measurable costs for homeowners. Hard water at 240 PPM costs the average household $800 to $1,200 per year in hidden expenses, including higher energy bills from scale-insulated water heaters, increased soap and detergent usage, and premature appliance failure. Many San Antonio homeowners discover this only after a water heater replacement or plumber visit.

Beyond hardness, San Antonio's water quality is generally within EPA guidelines for regulated contaminants. Chlorine is present at 1.5 mg/L as a disinfectant residual, which is normal for municipal water systems. If you notice a pool-like taste or experience dry skin, a whole-house carbon filter is the most common and affordable solution. For homeowners who want to understand the full picture, requesting your utility's annual Consumer Confidence Report provides neighborhood-level data.

ContaminantDetectedHealth GuidelineLegal LimitStatus
Hardness (as CaCO₃)240 PPM< 60 PPMNo federal limit⚠ Very Hard
Total Dissolved Solids380 PPM< 300 PPM500 PPM⚠ Elevated
PFAS (total)3 ppt4 ppt (EPA)4 ppt (2024)✓ OK
Lead1 ppb0 ppb (no safe level)15 ppb (action level)✓ Low
Chlorine / Chloramine1.5 mg/LTaste threshold ~1.04.0 mg/L✓ Normal
Nitrate4 mg/L5 mg/L10 mg/L✓ OK

Recommendations for San Antonio Homes

🧂 Water Softener
At 240 PPM (undefined GPG), San Antonio's water is very hard. Scale will accumulate in pipes, water heaters, and on fixtures. A salt-based ion exchange softener removes the calcium and magnesium causing the problem. For a typical San Antonio household of 2 to 4 people, a 48,000-grain softener is the right starting size.
Learn more about this solution →

About San Antonio's Water Supply

Water Utility: SAWS

Water Source: Edwards Aquifer

Population Served: 1,547,253

Hardness: 240 PPM (undefined grains per gallon)

Water quality can vary by neighborhood and season. The values above represent typical averages reported by SAWS. To get exact numbers for your address, request a copy of the most recent Consumer Confidence Report (CCR) from your utility, or have your water independently tested.

Compare San Antonio to Other Texas Cities

Houston

120 PPM · Hard

Dallas

100 PPM · Moderately Hard

Fort Worth

110 PPM · Moderately Hard

El Paso

265 PPM · Extremely Hard

Arlington

124 PPM · Hard

Corpus Christi

113 PPM · Moderately Hard

Frequently Asked Questions About San Antonio Water

Is San Antonio tap water safe to drink?
San Antonio's water meets EPA legal standards for drinking water safety. However, legal limits and health-optimal levels are different things. Review the contaminant table above for specific numbers and how they compare to both legal limits and health guidelines.
Do I need a water softener in San Antonio?
Yes. At 240 PPM (undefined GPG), San Antonio's water is very hard. Without a softener, expect visible scale buildup on faucets and shower heads, reduced water heater efficiency (15 to 25 percent higher energy costs), spotted dishes and glassware, and soap that does not lather well. A salt-based water softener is the standard solution. For a typical San Antonio home with 2 to 4 residents, a 48,000-grain system is the most common starting size.
What water filter is best for San Antonio?
The best filter depends on which contaminants you want to address. For chlorine taste and odor, an activated carbon filter is effective and affordable, available as under-sink, countertop, or whole-house systems. See our softener vs. filter guide to understand the difference between these categories.
Where does San Antonio's water come from?
San Antonio's drinking water is sourced from Edwards Aquifer and treated by SAWS.
What is the hardness of San Antonio water in grains per gallon?
San Antonio's water hardness is undefined grains per gallon (GPG), which equals 240 parts per million (PPM). This is classified as very hard. Most water softener manufacturers recommend treatment above 7 GPG. To convert: 1 GPG = 17.1 PPM.
Does San Antonio water damage tankless water heaters?
Yes. Most tankless water heater manufacturers recommend water hardness below 7 to 11 GPG (120 to 188 PPM). At undefined GPG, San Antonio's water exceeds this threshold. Scale buildup inside the heat exchanger reduces efficiency and can void the manufacturer's warranty. A water softener installed upstream of the tankless heater is the standard solution.
Is San Antonio water safe for babies and infants?
San Antonio's water meets all EPA safety standards and is generally considered safe for preparing infant formula. The hardness minerals (calcium and magnesium) are not harmful. If your home has older plumbing, running cold water for 30 seconds before use is a good precaution to flush any lead from pipes.
How much does hard water cost a San Antonio household per year?
At 240 PPM, hard water costs the average San Antonio household an estimated $800 to $1,200 per year in hidden costs. This includes 15 to 25 percent higher water heating bills from scale insulation, 50 to 75 percent more soap and detergent usage, shorter appliance lifespans (water heaters, dishwashers, washing machines), and increased plumbing maintenance. A water softener typically costs $600 to $1,500 installed and $50 to $100 per year in salt, which means most San Antonio households see a return on investment within 1 to 2 years.

Data sources. Water quality data compiled from EPA SDWIS, EWG Tap Water Database, USGS water hardness studies, and the SAWS Consumer Confidence Report. Hardness and contaminant levels represent typical average values and may vary by neighborhood and season. Last updated: 2026-02-12.