Ontario water heater problems such as fading hot water, a pilot that won't hold or a slow drip at the fittings are usually repairable with one part and a short visit. A tank leaking from its body is a replacement. Call the number on this page to be connected with a local plumber in Ontario.
How hard is Ontario's water on a heater?
Moderately. Ontario Municipal Utilities Company relies mostly on Chino Basin groundwater from city wells, plus purchased groundwater and imported State Water Project water. Its 2025 water quality report lists hardness averaging 124 mg/L in city groundwater (range 82 to 150 mg/L), 91 mg/L in imported water and 137 to 177 mg/L in the purchased groundwater supplies. At those levels a tank collects sediment steadily, and electric elements pick up a crust that shortens their life. A flush during the repair and a look at the anode rod are sensible add-ons, especially for a heater that has never been drained.
My house is from around 1980. What should the plumber check?
City-stats.com puts the median year built for Ontario homes at 1980, so many houses near downtown and in older tracts are already on a replacement heater, while Ontario Ranch homes are far newer. In older garages and closets the plumber will look at the flue connector, gas flex line, seismic straps and the cold-water shutoff, since these often date from an earlier install. Newer homes tend to have the opposite issue: an original heater reaching the age where valves and elements start to fail.
Will the city need a permit for this?
A simple part swap is generally treated as a repair, while a full replacement is permitted work. Ontario's Building Department, at 303 East B Street, takes applications electronically through the City's Citizen Portal Access website. Ask the plumber at the start whether your job will need one; if it becomes a replacement, they can file it. Either way, expect them to confirm the relief valve drains to a safe spot, the seismic straps are snug and the vent connector is sealed, since these are the items an inspector looks at on a new install.
A note on gas and water safety
If you smell gas near the heater, leave the house before doing anything else, then call 911 and SoCalGas at 1-800-427-2200 from outside. For water questions, OMUC disinfects with chloramines and free chlorine, reports no lead service lines in its system and takes calls at Utilities Customer Service, (909) 395-2050.
Water Heater Repair questions in Ontario
Does chloramine in the water affect water heater parts?
How often should a tank water heater be flushed?
Do I need a thermal expansion tank?
Is a water heater that is more than 10 years old worth fixing?
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