Low Water Pressure in House — Causes and Fixes

When your shower feels like a drizzle and the kitchen faucet barely fills a pot, low water pressure turns every water task into an exercise in patience. Sometimes it’s a simple fix you can handle in minutes. Sometimes it’s a bigger issue. Let’s figure out what’s going on.

First: Is It the Whole House or Just One Fixture?

This is the most important diagnostic question.

One fixture only: The problem is localized — usually a clogged aerator, showerhead, or a partially closed valve for that fixture.

One room (like bathroom only): Could be a partially closed supply valve, clogged lines to that room, or failing fixtures.

Whole house: The problem is systemic — main supply, pressure regulator, well pump, or municipal supply issue.

Most Likely Causes (By Scenario)

Single Fixture — Check These First

1. Clogged Aerator

The aerator is the little screen at the end of your faucet. Mineral deposits build up over time and restrict flow.

The Fix:

1. Unscrew the aerator by hand (or with pliers wrapped in tape to prevent scratching)
2. Disassemble and soak parts in vinegar or CLR for 30 minutes
3. Use an old toothbrush to scrub away deposits
4. Reassemble and reattach

Time: 15 minutes. Cost: Free.

2. Clogged Showerhead

Same idea — mineral buildup restricts the spray.

The Fix:

• Remove and soak in vinegar overnight, OR
• Fill a plastic bag with vinegar, rubber-band it around the showerhead overnight
• Scrub with an old toothbrush and rinse

Time: 5 minutes active, overnight soak. Cost: Free.

3. Partially Closed Supply Valve

Each fixture usually has its own supply valve (under sinks, behind toilets). If someone partially closed it, you’ll have reduced flow.

The Fix: Turn the valve fully counterclockwise (open). For quarter-turn valves, the handle should be parallel to the pipe.

Whole House — Systemic Issues

1. Main Shutoff Valve Not Fully Open

Your house has a main water shutoff valve (usually near the meter or where the main line enters). If it’s not fully open — maybe after a repair or inspection — pressure drops.

The Fix:

• Locate the main shutoff (often in the basement, garage, or outside near the meter)
• Turn it fully counterclockwise (or fully parallel for ball valves)
• Check pressure at multiple fixtures

2. Pressure Regulator Failure

Many homes have a pressure regulator (PRV) that reduces municipal pressure to a safe level for household plumbing. When these fail, they often fail partially closed, dropping your pressure.

Signs:

• Sudden pressure drop throughout the house
• Pressure was fine before, now it’s not
• Pressure varies wildly

The Fix: Pressure regulators can be adjusted or replaced. They’re usually located near the main shutoff.

• Adjusting: Turn the screw clockwise to increase pressure (if the regulator is adjustable)
• Replacing: $150-350 installed by a plumber

Note: If your home doesn’t have a PRV and you experience high pressure (above 80 psi), you should have one installed. High pressure damages fixtures and appliances.

3. Corroded or Clogged Pipes

Older homes with galvanized steel pipes develop internal corrosion and mineral buildup over decades. This narrows the pipes from the inside, reducing flow.

Signs:

• Home has galvanized pipes (grayish metal, often with visible threading)
• Pressure has been declining gradually over years
• Pipes are 40+ years old

The Fix: Pipe replacement (repiping) is the only real solution. This is a major project — $4,000-15,000+ depending on home size.

Note: Repiping makes sense when you’re doing major renovations anyway, or when the corrosion is causing other problems (discolored water, pinhole leaks).

4. Municipal Supply Issue

Sometimes low pressure isn’t your problem at all — it’s the city’s.

How to check:

• Ask neighbors if they’re experiencing the same issue
• Call your water utility — they may be doing maintenance or have a main break
• Check the utility’s website or social media for alerts

5. Peak Usage Times

Water pressure often drops during peak usage times in your neighborhood — early morning and early evening when everyone’s showering and watering lawns.

If this is your pattern: Consider a pressure booster pump (installed by a plumber) if the drop is significant and consistent.

Well Water — Special Considerations

If you’re on well water, low pressure has different causes:

Pressure tank issues:

• Check the pressure gauge on the tank
• Tank should maintain 40-60 psi typically
• Waterlogged tanks lose their air cushion and cause pressure fluctuations

Pump problems:

• Pump may be failing
• Pump may be undersized for your household demand
• Well yield may have dropped

Well system issues need a well specialist, not a regular plumber.

How to Test Your Water Pressure

Buy a pressure gauge that attaches to a hose bib (outdoor faucet). They cost $10-15 at any hardware store.

1. Attach the gauge to an outside faucet near the main supply
2. Turn the faucet fully open
3. Read the pressure

Normal range: 40-60 psi
Acceptable range: 30-80 psi
Too low: Below 30 psi (will affect fixtures and appliances)
Too high: Above 80 psi (can damage plumbing over time)

Can You Fix It Yourself?

✅ DIY-Friendly:

• Clean aerators and showerheads
• Open partially closed valves
• Adjust pressure regulator (if accessible and adjustable)
• Test pressure with a gauge

🛑 Call a Pro If:

• Pressure is low throughout the house after checking valves
• Pressure regulator needs replacement
• You suspect corroded/clogged pipes
• You’re on well water and the tank or pump is involved
• You need a pressure booster installed

Step-by-Step Diagnosis

1. Single fixture or whole house?

   • Single: Clean aerator/showerhead, check fixture valve
   • Whole house: Continue to step 2

2. Check main shutoff valve — fully open?

3. Check with neighbors — are they affected too? If yes, call utility.

4. Test pressure with gauge — what number are you getting?

5. Check pressure regulator (if you have one) — may need adjustment or replacement

6. Consider pipe age — galvanized pipes 40+ years old are likely the culprit if nothing else explains it

What a Plumber Will Do

Diagnostic visit ($75-150):

• Test pressure at multiple points
• Inspect main shutoff and pressure regulator
• Check for obvious pipe issues
• Diagnose well system (if applicable)

Common repairs:

• Pressure regulator replacement: $150-350
• Water line repair: $200-500
• Pressure booster installation: $300-800
• Repiping: $4,000-15,000+ (major project)

Prevention

• Clean aerators annually — 5-minute task that maintains flow
• Don’t over-tighten valves — you can damage them
• Know where your shutoffs are — and make sure they work
• Test pressure yearly — catch declining pressure early
• Consider water softening — if you have hard water, it reduces mineral buildup

The Bottom Line

Low water pressure usually comes down to: clogged fixtures (easy fix), closed valves (easy fix), pressure regulator (moderate fix), or pipe corrosion (major fix).

Start with the cheap stuff — aerators, valves, and a pressure test. If those don’t solve it, you’ll at least have useful information when you call a plumber.