Why San Antonio water leaves white crust on every fixture, what the SAWS hardness number means, how the supply differs in Boerne, Fair Oaks Ranch and Helotes, and how to clean limestone scale without damaging finishes.
San Antonio sits on limestone, and its tap water carries a lot of it. Anyone who has moved here from a soft water city notices within weeks: spotted shower doors, crusty faucet aerators, a ring in the toilet bowl and a kettle that rattles with flakes.
This guide explains where that scale comes from, how much of it to expect in different parts of the area, and the cleaning approaches that remove it without ruining glass, chrome or stone.
The San Antonio Water System draws its drinking water from groundwater in four aquifers: the Edwards, Carrizo, Trinity and Wilcox. SAWS describes the Edwards as heavily faulted and fractured carbonate limestone within the Balcones fault zone. Water moving through that rock dissolves calcium carbonate, and it stays in the water all the way to your tap.
SAWS puts typical hardness at 15 to 20 grains per gallon. SAWS is clear that hard water is not a health hazard and that the calcium carbonate from the Edwards and Trinity aquifers occurs naturally. It is a cleaning problem, not a safety one.
SAWS also adds about 1 part chlorine per million parts of water at its production facilities. That is the faint pool smell some people notice at the tap, and it has no effect on scale.
Helotes owns no utilities of its own, so SAWS provides its water and sewer, and homes there see the same hardness as the city.
Fair Oaks Ranch Utilities pumps Trinity Aquifer groundwater from city wells and blends it with treated water bought from the Guadalupe-Blanco River Authority. Boerne Utilities draws from Boerne City Lake, from Canyon Lake through the river authority and from groundwater wells. The City of Boerne says hardness varies across town and suggests a home test kit. In both places, a house on one street can see more spotting than a house a mile away, depending on the blend.
If you are not sure what your home gets, an inexpensive test strip from a hardware store gives a grains per gallon reading and tells you how aggressive your routine needs to be.
Scale forms anywhere water evaporates and leaves its minerals behind. In a San Antonio home that usually means:
Mild acids dissolve calcium carbonate, which is why white vinegar and citric acid work on scale. They also attack marble, travertine and limestone countertops, which are made of the same mineral, so keep them off natural stone entirely. On chrome and glass, apply the cleaner, give it time to work and wipe with a soft cloth; scrubbing with abrasive pads or steel wool scratches the finish and gives new scale more to grip.
Heat plays a part too. With about 122 days a year at 90 degrees or hotter, bathrooms and garages stay warm, and water evaporates fast, leaving its minerals in place. Squeegee shower glass after every use and dry faucets with a towel, and the deposits stay thin enough to wipe away.
Old glass that has been left with scale for years can etch, which no cleaner can reverse. When TotalCare Cleaning comes to San Antonio, the One-Time Deep Clean will treat shower glass for hard water spots and detail faucets, and a recurring plan will keep the new spots from setting. See the deep cleaning guide and the recurring cleaning guide.
The questions San Antonio homeowners ask most often about this topic, answered plainly.
TotalCare Cleaning will service San Antonio and surrounding areas with background-checked cleaners and is insured up to $1 million. Re-clean guarantee: if we missed something, tell us by the end of the next day and we come back to fix it. Beyond Clean. TotalCare.
