Start small
A weak shower or slow-filling sink is frustrating, and in an older home it is easy to blame the pipes. Sometimes that is right. But a clogged aerator, a worn cartridge, a half-closed valve or a failing pressure regulator can all cause the same symptom for far less money. Hard water scale makes the small parts clog more often.
The pattern tells you where to look. Low pressure at a single fixture is usually that fixture. Low pressure everywhere, or getting worse slowly over years, points further upstream: the main valve, the regulator, the main line or the house supply pipe itself.
Follow the pattern
- IfOnly one faucet or shower is weakClean the aerator or showerhead and check the fixture's shutoff valve is fully open.
- IfOnly hot water is weakCheck the water heater's valves and connections, and look for galvanized nipples at the heater.
- IfThe whole house dropped suddenlyCheck that the main shutoff is fully open, and ask whether there is city work nearby.
- IfThe whole house has faded over yearsAsk a plumber to check the pressure regulator and the supply pipe material.
Simple checks you can do
- Clean aerators.Unscrew faucet tips and rinse out scale and grit.
- Soak showerheads.Mineral buildup from hard water can choke the holes.
- Open valves fully.Check fixture shutoffs and the main shutoff are fully open.
- Compare fixtures.Run the outside hose bib near the main. Strong there but weak inside suggests interior pipe.
Causes a plumber may find
| Cause | Typical fix |
|---|---|
| Worn faucet cartridge | Replace the cartridge or fixture |
| Failing pressure regulator | Adjust or replace the regulator |
| Corroded main shutoff | Replace the valve |
| Galvanized main line | Replace the line from meter to house |
| Narrowed galvanized interior pipe | Partial or whole-house repipe |
| Hidden leak | Locate and repair; reroute if under a slab |
Ask before any big fix
- What did the pressure gauge read?
- Is there a pressure regulator, and is it working?
- What is the main line from the meter made of?
- Would replacing the main line alone help, or is interior pipe also narrowed?
Common questions
Will a repipe definitely fix low pressure?
If narrowed pipe is the cause, a repipe helps. If the problem is the regulator or the city supply, it may not. Confirm the cause first.
Can pressure be too high?
Yes. High pressure stresses pipes and fixtures. A plumber can check whether a regulator is needed or working.
Does low pressure mean a leak?
It can. A meter test with every fixture off helps rule that in or out.
General information for Fullerton, not a quote or professional advice. In an emergency, call 911.