What Causes Low Water Pressure in House (Troubleshooting Guide)

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Quick answer
Confirm the symptom
Tools and prep
Step-by-step troubleshooting
Common causes table
Parts matching
When to call a pro
FAQ
Related guides

Quick answer

Low water pressure in your house can be caused by a closed shut-off valve, clogged aerators, or mainline issues. Check the main valve, clean fixtures, and inspect for leaks to resolve it.

Confirm the symptom

Low water pressure from all faucets
Weak shower flow
Slow toilet refill
Low pressure from outdoor spigots

Tools and prep

Adjustable wrench
Plunger
Pipe cleaner or old toothbrush
Water pressure gauge
Bucket or towel
Turn off main water supply before major repairs

Step-by-step troubleshooting

Check Main Water Valve
Do: Locate and ensure the main water valve is fully open.
Observe: Valve is open but pressure remains low.
Means: Issue may be downstream or with the municipal supply.
Next: Check individual fixture valves
Check Individual Fixture Valves
Do: Ensure all fixture valves under sinks and appliances are fully open.
Observe: Valves are open but pressure is still low.
Means: Problem may be in the plumbing lines or pressure regulator.
Next: Test water pressure
Test Water Pressure
Do: Attach a water pressure gauge to an outdoor spigot or laundry sink.
Observe: Pressure is below 40 psi or above 80 psi.
Means: Pressure regulator may be faulty or municipal supply is low.
Next: Inspect pressure regulator
Inspect Pressure Regulator
Do: Check the pressure regulator near the main water line for damage or wear.
Observe: Regulator is damaged or not functioning properly.
Means: Regulator needs repair or replacement.
Next: Clean or replace aerators
Clean or Replace Aerators
Do: Remove and clean aerators on faucets with a pipe cleaner or toothbrush.
Observe: Debris or mineral buildup is present.
Means: Clogged aerators are reducing water flow.
Next: Check for leaks
Check for Leaks
Do: Look for damp spots, mold, or listen for running water when no fixtures are in use.
Observe: Leaks are detected in pipes or fixtures.
Means: Leaks are reducing water pressure.
Next: Call a professional plumber
Flush Water Heater
Do: Drain and flush the water heater to remove sediment buildup.
Observe: Sediment is present in the drain water.
Means: Sediment buildup is restricting water flow.
Next: Replace pressure regulator if necessary

Common causes

Cause	Likelihood	Difficulty	Part often needed
Closed Main Water Valve Partially closed valve restricts water flow to the entire house.	Common	Easy	None
Clogged Aerators Mineral deposits block water flow from faucets.	Common	Easy	Aerator
Faulty Pressure Regulator Malfunctioning regulator can't maintain proper water pressure.	Sometimes	Medium	Pressure regulator
Leaky Pipes Leaks reduce water pressure by allowing water to escape the system.	Sometimes	Hard	Pipe repair kit or replacement
Sediment in Water Heater Sediment buildup restricts water flow from the heater.	Sometimes	Medium	Water heater flush kit
Municipal Water Supply Issues Low pressure from the city or well system affects the entire house.	Rare	N/A	None
Clogged Pipes Mineral buildup or debris in pipes restricts water flow.	Sometimes	Hard	Pipe cleaning or replacement

Parts matching

Common parts needed to fix low water pressure include:

Aerator for faucets
Pressure regulator
Pipe repair kit
Water pressure gauge
Water heater flush kit

Purchase a water pressure gauge to accurately measure pressure and identify issues with the regulator or municipal supply.

When to call a professional

Persistent low pressure after checking all valves and aerators
Suspected pipe leaks you cannot locate or repair
Faulty pressure regulator requiring replacement
Signs of water damage or mold indicating hidden leaks
Low pressure from the municipal supply that doesn't resolve

FAQ

How do I check my home's water pressure?

Attach a water pressure gauge to an outdoor spigot or laundry sink faucet. The ideal range is 40–80 psi.

Can low water pressure be fixed without a professional?

Yes, if caused by clogged aerators or a closed valve. For issues like leaks or faulty regulators, call a professional.

Why is only one faucet low on pressure?

A clogged aerator or partially closed valve at that specific fixture is likely the cause.

How often should I flush my water heater?

Annually to prevent sediment buildup that can reduce water pressure and heater efficiency.

What if my water pressure is fine but flow is still low?

Check for clogged aerators, showerheads, or partially closed valves. High water pressure with low flow may indicate a plumbing blockage.