First: one fixture or the whole house?
If only one faucet or shower is weak, the problem is almost always at that fixture. If every faucet is weak, look at the main line, the pressure regulator or the pipes themselves.
1. A clogged aerator or showerhead
Hard water leaves mineral scale in the small screens on faucets and showerheads. Unscrew the aerator or showerhead and soak it in white vinegar for an hour, then rinse it out.
2. A worn faucet cartridge
If cleaning the aerator doesn’t help, the cartridge inside the faucet may be clogged or worn. Replacing it usually restores full flow.
3. A partly closed valve
Check the shutoff valves under the sink and the main shutoff. A valve left partly closed after a repair can choke the flow.
4. A failing pressure regulator
The bell-shaped regulator near your main shutoff can wear out and start cutting pressure too much. A plumber can test the pressure with a gauge and adjust or replace it.
5. Galvanized pipes
In homes built before the 1960s, galvanized steel pipes rust from the inside until little water gets through. Low pressure throughout the house, often with rusty water, is the classic sign.
6. A hidden leak
Water escaping from a hidden leak, including under the slab or in the line from the meter, never reaches your faucets. Check your water meter with everything off. If it’s moving, you have a leak.
7. Low pressure from the street
Sometimes the pressure is low before it reaches your house, especially on higher ground or at times of heavy demand. Your water utility can tell you the typical pressure in your area.
When to call a plumber
- Pressure is low everywhere in the house.
- You see rusty water along with low pressure.
- Your water meter moves when nothing is on.
- Pressure suddenly dropped and didn’t come back.