Where the scale comes from
Fullerton's water utility supplies a blend of local groundwater and imported water. That water carries dissolved calcium and magnesium, which is what hard water means. When water sits, heats or evaporates, those minerals drop out as white or tan crust.
The smallest openings clog first: the mesh screen in a faucet aerator, the tiny nozzles of a shower head, the inlet screen on a washing machine hose and the passages inside single-handle cartridges. Because the clog is at the fixture, everything upstream can be fine.
Scale or pressure?
- IfOne faucet is weak and the one beside it is normalThenScale or debris at that faucet is the likely cause.
- IfA shower sprays sideways or in thin uneven jetsThenNozzles are partly blocked; clean or replace the head.
- IfHot side is weak at one fixture, cold side is fineThenLook at that fixture's hot-side cartridge or stop valve, and at the water heater.
- IfEvery fixture is weak, including hose bibsThenTreat it as a supply or regulator issue instead.
Cleaning an aerator or shower head
- Plug the drain.Small parts love to disappear down sinks.
- Unscrew the part.Most aerators turn off by hand; wrap a cloth around them if pliers are needed so the finish is not scratched.
- Soak in vinegar.Plain white vinegar softens mineral scale. Soak until the crust loosens, then brush gently.
- Rinse and flush.Run the faucet briefly without the aerator to clear loose debris from the line, then reinstall.
- Replace if worn.Aerators and shower heads are inexpensive parts. Cracked or badly pitted ones are better replaced.
Where scale shows up beyond the faucet
| Part | What happens | Who usually handles it |
|---|---|---|
| Water heater tank | Sediment settles at the bottom, causing popping and less efficiency | Homeowner flush per manual, or plumber |
| Tankless heater | Scale in the heat exchanger reduces performance | Plumber, per manufacturer's descaling schedule |
| Faucet and shower cartridges | Stiff handles, drips, weak flow | Homeowner or plumber |
| Toilet fill valves | Sticking, running toilets | Homeowner or plumber |
| Regulator strainer | Gradual whole-house drop | Plumber |
When to bring in a plumber
If cleaning screens does not help, if cartridges need replacing and you are not comfortable shutting off and disassembling a valve, or if several fixtures are affected, a licensed plumber can sort out whether the issue is scale, pipe condition or supply. Ask what they found at each fixture so you know whether the fix is local or whole-house.
Common questions
Is hard water unsafe to drink?
Hardness minerals are generally a nuisance rather than a health concern. For water quality questions, Fullerton's water utility publishes reports; check with the city.
How often should I clean aerators?
There is no fixed schedule. When flow drops or the stream looks uneven, it is time to check.
Does scale affect water heater life?
Sediment buildup can reduce efficiency and stress the tank. Follow the manufacturer's flushing guidance or ask a plumber.
General information for Coyote Hills, not a quote or professional advice. In an emergency, call 911.