Why is my water pressure low?
Whole-house or one fixture — how to track down the cause.
By The T.A.P. Team · April 2024 · 6 min read
Low water pressure comes down to one key question: is it the whole house or just one fixture? A single slow faucet is usually a clogged aerator or cartridge you can clean yourself. Low pressure everywhere points to something bigger — a failing pressure regulator, a partly closed main valve, old galvanized pipes, or a hidden leak. Here's how to narrow it down.
- 1Is it one fixture or the whole house?
- 2Unscrew and clean the faucet aerator.
- 3Make sure the main shutoff and meter valves are fully open.
- 4Is it both hot and cold — or just one?
- 5Look for wet spots or a moving meter (possible leak).
First: one fixture or the whole house?
This single question splits the problem in half. If only one faucet or shower is weak, the cause is local — a clogged aerator, a gummed-up cartridge, or a closed supply valve under the sink. If pressure is low everywhere, the cause is on the main line: a regulator, a valve, the pipes, or a leak. Check a few fixtures before you go further.
One slow fixture (usually an easy fix)
For a single weak faucet, unscrew the aerator on the tip and rinse out the mineral and debris — this alone fixes a huge share of "low pressure" complaints in our hard-water area. A weak shower often just needs the showerhead descaled or replaced. If hot is weak but cold is fine (or vice versa), the supply valve or cartridge on that side is the suspect.
Whole-house low pressure
When everything is weak, start at the source: make sure the main shutoff and the valves at the meter are fully open (a half-closed valve after a repair is common). Next is the pressure-reducing valve (PRV) where the main enters the house — these fail over time and drop pressure. Old galvanized-steel pipes also corrode shut from the inside, choking flow throughout an older home.
The one you don't want: a hidden leak
A sudden pressure drop across the whole house can mean a leak — including a slab leak under the foundation, which North Texas's shifting clay soil makes common. Check your water meter with everything off: if it's still creeping, water is escaping somewhere. That's a call for a pro.
| Symptom | Likely cause | What to do |
|---|---|---|
| One slow faucet | Clogged aerator/cartridge | Clean or replace it |
| Weak shower only | Scaled showerhead | Descale or replace |
| Whole house weak | PRV or valve | Check valves; test/replace PRV |
| Old home, all fixtures | Corroded galvanized pipe | Consider a repipe |
| Sudden drop + wet spots | Possible leak | Check the meter; call a pro |
You can DIY
- Clean faucet aerators
- Descale showerheads
- Open the main and meter valves fully
- Check the meter for a hidden leak
- Open under-sink supply valves
Call a pro
- Testing or replacing the PRV
- A slab or underground leak
- A corroded galvanized repipe
- Water-main or meter-side issues
- Pressure problems after a repair
Chasing low pressure by swapping fixtures is a waste if the real problem is a failing regulator or a leak. The right first move is to isolate whether it's one fixture or the whole house, then work from the fixture (aerator) or the source (valves, PRV, meter) accordingly. Diagnose the zone, then fix the part.
Hard water and shifting soil in DFW
North Texas has hard water that clogs aerators and showerheads faster than most places, and expansive clay soil that stresses buried lines. Both show up as low pressure. We track down pressure problems across Plano, Frisco, and McKinney, from a single clogged aerator to a whole-house regulator or leak. See our plumbing services.
The short version
- First figure out if it's one fixture or the whole house — that splits the problem in half.
- One slow faucet is usually a clogged aerator or cartridge you can clean yourself.
- Whole-house low pressure points to a valve, the pressure regulator, or the pipes.
- A failing pressure-reducing valve (PRV) is a common whole-house cause.
- A sudden drop everywhere can mean a hidden leak — check the meter with water off.
- In DFW, hard water clogs fixtures and clay soil stresses buried lines.
Low water pressure — frequently asked questions
Low pressure you can't fix?
Get a free diagnosis — from a clogged aerator to a whole-house regulator or leak. Serving Dallas–Fort Worth & North Texas for over 25 years.