San Antonio hard water: 15 to 20 grains per gallon

San Antonio tap water is very hard: typically 15 to 20 grains per gallon. That range comes from San Antonio Water System's water quality FAQ (opens in new tab). In ppm, that is about 257 to 342.

Why is San Antonio water so hard?

San Antonio gets much of its water from underground aquifers, including the Edwards and the Trinity. SAWS says the calcium carbonate in that water is naturally occurring. Groundwater moves slowly through limestone, and limestone is mostly calcium carbonate. The water dissolves some of it along the way.

SAWS defines hardness as the amount of calcium and magnesium in the water, measured as calcium carbonate. That is the same way every utility reports it, so you can compare cities directly.

What 15 to 20 grains per gallon means at home

• Fast-building white crust on faucets and shower heads
• Spotty dishes and cloudy glasses
• Scale inside water heaters, which can shorten their life
• Stiff laundry and soap that does not lather

Do you need a water softener in San Antonio?

At 15 to 20 grains per gallon, most homes see a big difference with a softener. It protects the water heater and cuts down on cleaning. Because the water is so hard, sizing matters. A softener that is too small recharges too often and wastes salt.

Get your own tap tested so the system fits your home. Compare options in reverse osmosis vs. a water softener, and see typical costs. Nearby, Austin's water is much softer.

Common questions

Keep reading

DataWater hardness by cityHow hard the tap water is in US cities, from each utility report. City dataAustin water hardness: 5.4 grains per gallonAbout 5.4 grains per gallon. Moderately hard. GuideHow much does a water softener cost installed?Installed price ranges, running costs, and what drives the price. GuideDo I need a water softener with city water?It depends on your city. Here is how to decide.