As of late September 2026, the water heater behind the service-porch door in this Riverside house is the one appliance I’ve never touched. It heats, I shower, and I assumed a tank with no moving parts didn’t need anything from me until the day it quit.
Here, that assumption meets very hard water. Riverside Public Utilities publishes its hardness numbers in its water quality report, and they aren’t small.
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What Riverside Public Utilities reports
The report lists hardness at an average of 194 mg/L, in a range of 180 to 210 mg/L, or about 11 grains per gallon, and the utility lists it as naturally present in the environment. It isn’t a safety problem. It’s a mineral load. The U.S. Geological Survey classifies water with “more than 180 mg/L as very hard,” so by that scale Riverside’s tap water is very hard.
What hard water does inside the tank
USGS spells out what happens next: “When hard water is heated, such as in a home water heater, solid deposits of calcium carbonate can form.” And the cost of ignoring it: USGS says that scale can shorten the life of equipment, raise the cost of heating the water, lower the efficiency of electric water heaters and clog pipes…