A tankless water heater has no tank for sediment to settle into. Every gallon runs straight through a compact heat exchanger, and in hard water the minerals that come out of solution when the water heats up stay right there, in the narrow passages that make the unit work.
Temecula's water is hard by any measure, and how hard depends on the source feeding your street at the moment. That is why the flush schedule matters more here than it does on softer water closer to the coast.
How hard is the water feeding a Temecula tankless heater?
Very hard for most homes. Rancho California Water District's 2025 report lists imported water at about 230 mg/L and its own wells averaging 151 mg/L, with individual wells from 5 to 340 mg/L. Homes on Eastern Municipal Water District's Skinner supply see about 13.4 grains per gallon, roughly 229 mg/L.
RCWD blends imported water with water from its wells, and the mix shifts through the year, so the hardness at your tap moves around inside that range. Our water hardness by city table lists each figure next to its report.
Hardness is about scale, not safety. Both districts meet state and federal drinking water standards. The minerals simply drop out as scale wherever water gets hot, and a tankless heat exchanger is the hottest, tightest spot in the house.
What does a tankless flush actually do?
It circulates a descaling solution through the heat exchanger for a set time, usually with a small pump and hoses on the unit's service valves, then flushes it out with fresh water. The solution dissolves the scale that the burner or elements have baked onto the inside walls.
| Step | With service valves | Without service valves |
|---|---|---|
| Isolate the heater | Close two valves at the unit | Shut off water to the house |
| Connect the pump | Hoses thread onto the valve ports | Lines cut or disconnected first |
| Circulate the solution | Same either way | Same either way |
| Restore water | Open the valves and purge air | Reconnect lines and check for leaks |
If your unit has no service valves, adding them at the first flush makes every later flush simpler.
The steps are the same on most brands: shut off the gas or power, close the service valves, connect the pump and hoses, circulate the solution, drain and rinse, then clean the inlet screen and restart the unit. The manual for your model sets the time and the solution it allows.
A flush done on schedule keeps the unit's efficiency close to new. Skipped for years, scale can harden past the point where a flush clears it, and the repair turns into replacing the heat exchanger or the heater.
Tankless unit acting up or overdue for a flush? We will check the heat exchanger, flush it, and tell you if anything else needs attention, with the price in writing first.
Does a water softener mean you can skip the flush?
No. A softener ahead of the heater removes most of the calcium and magnesium, so scale builds much more slowly, but the flush still belongs on the calendar. It also clears the inlet screen, which catches grit regardless of hardness.
On softened water, many owners stretch the time between flushes. The unit's manual is still the rule for how far. Our page on water softener installation in Temecula covers what a softener does with the valley's water.
What are the signs a Temecula tankless heater is overdue?
Water that takes longer to get hot, a temperature that drifts at the shower, a heater that shuts down at high flow, and scale or descaling error codes on the display. Any of these on hard water usually means the heat exchanger is scaling up.
Some units also get louder, a ticking or rushing sound from the cabinet when they fire. If the heater has gone more than a year without a flush in Temecula, assume scale before assuming a failed part.
Who should flush the heater, you or a plumber?
Handy owners can do it with service valves, a pump kit and the manual. It is worth having a technician do it when the unit has no service valves, is past due by several years, or shows error codes after a flush.
Pipe Dream Plumbing flushes and repairs tankless units across the valley. Our page on tankless water heaters in Temecula explains the service, the tankless water heater page covers installs, and the tankless cost guide explains what goes into the price. We work all over Temecula and nearby Murrieta from our office on Emerson Way, and our crew are San Diego natives who speak English and Spanish. Hablamos español.
Need a tankless heater flushed or checked in Temecula? Call (951) 404-1594. A real person answers every call, and you get a flat, written price before any work starts.
Our Temecula office: 33433 Emerson Way, Temecula, CA 92592. Office hours and directions
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