San Antonio Hard Water: What 15 to 20 Grains Means for Your Home

If you moved to San Antonio from somewhere else, you probably noticed the water inside a week. Spots on every glass out of the dishwasher. A white crust around the faucet. A shower door that never looks clean. That is hard water, and in San Antonio it is not a little hard. By the federal scale, it is very hard.

This article covers what the number actually is, where it comes from, what it does to a house, and how to figure out what your home needs. Every figure here comes from the utility or a government source, and we name it so you can check.

How hard is San Antonio water?

The San Antonio Water System (SAWS) publishes its own number. In its Water Quality FAQs, SAWS says: “The typical hardness in the water provided by SAWS ranges from 15 to 20 gpg (grains per gallon).” SAWS defines hardness as the concentration of calcium and magnesium in the water, expressed as calcium carbonate.

Grains per gallon is the unit softener companies use. Labs and the U.S. Geological Survey use milligrams per liter (mg/L). A grain is 64.8 milligrams and a gallon is 3.785 liters, so one grain per gallon works out to about 17.1 mg/L. That puts SAWS water at roughly 257 to 342 mg/L.

The USGS scale calls anything above 180 mg/L very hard. San Antonio is well past that line, by the utility’s own figure.

Why it is so hard

SAWS draws from the Edwards and Trinity aquifers. The Edwards is a limestone aquifer, and limestone is calcium carbonate. Water that moves through rock made of calcium picks up calcium, and that is what shows up at your tap.

Is hard water bad for you?

No, and we are not going to tell you it is. SAWS states plainly that hard water is not a health hazard, and cites the National Research Council finding that hard drinking water contributes a small amount toward the calcium and magnesium people need in their diet.

Hard water is a problem for your house, not your health. That is still a real problem, because a house is expensive.

What 15 to 20 grains does to a San Antonio home

• Water heaters: when hard water is heated, calcium drops out as scale. It settles in the bottom of a tank heater and coats the inside of a tankless one. Scale between the burner and the water can make the heater work harder.
• Fixtures and glass: the white spots on shower doors, faucets and dishes are dried calcium. At this hardness they come back fast after you clean them.
• Appliances: dishwashers, washing machines, ice makers and coffee makers all have small valves and lines that scale narrows over time.
• Soap and skin: hard water does not lather well, so you use more soap and shampoo, and it leaves a film behind. That film is what a lot of people feel as dry skin and dull hair.

Then there is the chlorine. SAWS says it adds about 1 part chlorine per million parts of water at its production facilities to keep the water free of bacteria on the way to you. That is the job it should be doing. It is also the swimming-pool taste and smell many people notice at the tap. A good whole-home system handles the hardness and the chlorine together.

Which system fits San Antonio water?

At this hardness, the right answer for most homes on SAWS is a softener paired with carbon filtration. A softener uses ion exchange to take out the calcium and magnesium. The carbon is there for the chlorine. Those are two different jobs, and our whole-home systems do both in one tank.

For most 3 to 4 bedroom homes

The Standard Whole-Home Softener + Filtration is a 48,000 grain softener with coconut-shell carbon rated for chlorine and chloramine. It is our most popular system, and the one built for most 3 to 4 bedroom homes on city water.

For larger homes or bigger families

Harder water and more people means the softener fills up faster. The XL Whole-Home Softener + Filtration is the same hardware at 64,000 grains, so it goes longer between regenerations. For large homes with heavy use, the Dual Tank system for city water runs 96,000 grains with a separate carbon tank that backwashes itself clean.

If you want to skip salt

The Salt-Free Water Conditioner needs no salt and no drain line. It helps prevent scale from sticking to pipes and your water heater. To be clear about the trade-off: it prevents scale, it does not remove hardness. If soft water is what you want, that takes a softener.

For the water you drink

A whole-home system is not a drinking water system. For the water you drink and cook with, the HW800 AlkaPro tankless reverse osmosis system sits under the kitchen sink and is certified to NSF/ANSI 58. It is rated to reduce dissolved solids, chlorine and heavy metals such as lead.

Outside SAWS? Your water may be a different story

Not every home in the metro is on SAWS. Towns like Schertz and Cibolo run their own water, so their numbers are their own. Out toward New Braunfels and Boerne, plenty of properties are on a private well, and a well brings iron and sulfur into the picture along with hardness. That needs a different build, like our Dual Tank system for well water.

Not sure who supplies your home? Enter your ZIP on our check your water by ZIP code page. If you are in the city, our water softener installation in San Antonio page covers how we size and install.

San Antonio hard water: common questions

What is the water hardness in San Antonio?

SAWS publishes a typical range of 15 to 20 grains per gallon, which is about 257 to 342 mg/L. The USGS classifies anything above 180 mg/L as very hard.

Do I really need a water softener in San Antonio?

You do not need one for your health. SAWS says hard water is not a health hazard. You need one if you want to protect your water heater, fixtures and appliances from scale, and stop fighting spots on glass. At 15 to 20 grains, that scale builds up quickly, so it is worth seeing your own number before you decide.

What size water softener do I need?

It depends on your hardness and how much water your household uses. Our Standard is 48,000 grains, the XL is 64,000 and the Dual Tank is 96,000. We size it to your water and your household, not just the square footage of the house.