You turn on the shower and get a disappointing trickle instead of a powerful spray.
The kitchen faucet barely fills a pot. The washing machine takes forever to complete a cycle.
Low water pressure is one of the most frustrating plumbing problems—and one of the most common. But before you call a plumber, it helps to understand what’s causing the problem.
Some causes are simple DIY fixes. Others require professional help. This guide will help you diagnose the issue and decide on the right solution.
How to Diagnose Low Water Pressure
Before diving into causes, let’s figure out the scope of your problem.
Is It Affecting One Fixture or the Whole House?
Single fixture: The problem is likely localized—a clogged aerator, faulty valve, or supply line issue.
Multiple fixtures in one area: Could be a branch line problem or localized pipe issue.
Whole house: The problem is in your main supply, pressure regulator, or municipal supply.
Is It Hot Water, Cold Water, or Both?
Cold water only: Problem is before the water heater (supply side).
Hot water only: Problem is with the water heater or hot water lines.
Both: Problem is in the main supply or throughout the system.
Is It Constant or Intermittent?
Constant low pressure: Likely a physical restriction or system issue.
Intermittent: Could be demand-related, municipal supply fluctuations, or a failing component.
Cause #1: Clogged Aerators
Likelihood: Very Common | DIY Fix: Yes | Cost: Free
The aerator is the small screen at the tip of your faucet. It mixes air with water for a smooth flow and catches debris.
Symptoms
- Low pressure at one faucet only
- Uneven or sputtering flow
- Visible debris in the water stream
The Fix
- Unscrew the aerator (turn counterclockwise)
- Disassemble and rinse each component
- Soak in vinegar overnight if mineral buildup is heavy
- Use a toothbrush to scrub away deposits
- Reassemble and reinstall
Time required: 10-15 minutes
Cause #2: Clogged Showerhead
Likelihood: Very Common | DIY Fix: Yes | Cost: Free-$30
Similar to aerators, showerheads accumulate mineral deposits that restrict flow.
Symptoms
- Weak shower pressure
- Uneven spray pattern
- Some nozzles blocked
The Fix
Option 1: Clean in place
- Fill a plastic bag with white vinegar
- Secure bag around showerhead with rubber band
- Soak overnight
- Remove and run water to flush
Option 2: Remove and clean
- Unscrew showerhead
- Soak in vinegar solution for several hours
- Scrub with toothbrush
- Use a toothpick to clear individual nozzles
- Reinstall
When to replace: If cleaning doesn’t help, a new showerhead costs $20-$100 and takes 5 minutes to install.
Cause #3: Partially Closed Valves
Likelihood: Common | DIY Fix: Yes | Cost: Free
Your home has several shut-off valves. If any are partially closed, water pressure suffers.
Valves to Check
Main shut-off valve: Usually near where the water line enters your home. Should be fully open (gate valves: turn counterclockwise until it stops; ball valves: handle parallel to pipe).
Water meter valve: Located at the meter, usually near the street. Should be fully open. (Note: This is utility property—contact them if it needs adjustment.)
Fixture shut-off valves: Under sinks, behind toilets, behind washing machine. Should be fully open.
Common Scenarios
- Valve accidentally bumped partially closed
- Valve not fully reopened after repair work
- Valve handle broken, preventing full opening
The Fix
Locate and fully open all valves. If a valve is stuck or broken, call a plumber.
Cause #4: Failing Pressure Regulator
Likelihood: Moderate | DIY Fix: No | Cost: $250-$500
Many homes have a pressure regulator (also called a pressure-reducing valve or PRV) that maintains consistent pressure from the municipal supply.
Symptoms
- Sudden change in pressure (high or low)
- Pressure fluctuations throughout the day
- Pressure too high or too low throughout the house
How to Test
Use a pressure gauge (available at hardware stores for $10-$20):
- Attach gauge to an outdoor hose bib
- Turn on the water
- Read the pressure
Normal range: 40-60 PSI Too low: Below 40 PSI Too high: Above 80 PSI
The Fix
Pressure regulator replacement requires a plumber. The regulator itself costs $50-$150; total replacement runs $250-$500.
Cause #5: Corroded or Clogged Pipes
Likelihood: Moderate (older homes) | DIY Fix: No | Cost: $500-$15,000+
Older pipes—especially galvanized steel—corrode from the inside, gradually restricting flow.
Symptoms
- Gradual pressure decrease over months/years
- Rusty or discolored water
- Pressure problems throughout the house
- Home built before 1970 with original plumbing
Pipe Materials and Corrosion Risk
| Material | Corrosion Risk | Typical Lifespan |
|---|---|---|
| Galvanized steel | High | 20-50 years |
| Copper | Low | 50-70 years |
| PEX | Very low | 40-50+ years |
| CPVC | Low | 50-75 years |
The Fix
If corrosion is the cause, the solution is repiping—replacing the corroded pipes with modern materials. This is a major project:
- Partial repipe: $1,500-$5,000
- Whole-house repipe: $5,000-$15,000+
Cause #6: Leaks in the System
Likelihood: Moderate | DIY Fix: Sometimes | Cost: Varies
Water escaping through leaks means less pressure at your fixtures.
Symptoms
- Unexplained increase in water bill
- Wet spots in yard or basement
- Sound of running water when nothing is on
- Water meter spinning when no water is being used
How to Check for Leaks
- Turn off all water-using appliances
- Check your water meter
- Wait 1-2 hours without using any water
- Check meter again
- If it moved, you have a leak
The Fix
- Visible leaks: May be DIY-repairable
- Hidden leaks: Require professional leak detection
- Slab leaks: Require specialized repair
Cause #7: Water Heater Issues
Likelihood: Moderate | DIY Fix: Sometimes | Cost: $100-$1,500
If low pressure affects only hot water, the water heater is likely involved.
Possible Causes
Sediment buildup: Reduces tank capacity and can clog outlet.
Shut-off valve partially closed: Check the valve on the cold water inlet.
Failing dip tube: Causes cold water to mix with hot at the top of tank.
Undersized water heater: Can’t keep up with demand.
The Fix
- Sediment: Flush the tank (DIY or professional)
- Valve: Open fully (DIY)
- Dip tube: Replace (professional recommended)
- Undersized: Consider upgrade (professional)
Cause #8: Peak Demand Times
Likelihood: Common | DIY Fix: N/A | Cost: Free
Municipal water pressure can drop during high-demand periods.
When It Happens
- Morning hours (everyone showering)
- Evening hours (cooking, laundry, irrigation)
- Hot summer days (lawn watering)
- After water main breaks (while system recovers)
How to Confirm
- Pressure is fine at off-peak times
- Neighbors experience the same issue
- Problem is consistent at certain times
Solutions
- Adjust usage to off-peak times
- Install a pressure booster pump ($300-$800)
- Contact your water utility if pressure is consistently below acceptable levels
Cause #9: Municipal Supply Issues
Likelihood: Occasional | DIY Fix: No | Cost: Free (utility’s responsibility)
Sometimes the problem isn’t in your home at all.
Possible Causes
- Water main break
- Hydrant flushing
- Construction affecting lines
- Utility maintenance
- Drought conditions
How to Confirm
- Check with neighbors
- Contact your water utility
- Check utility website/social media for alerts
What to Do
If the utility confirms an issue, wait for them to resolve it. If they claim pressure is normal at the meter, the problem is on your side.
Cause #10: Undersized Main Supply Line
Likelihood: Less Common | DIY Fix: No | Cost: $1,500-$5,000
Some older homes have undersized supply lines that can’t deliver adequate flow for modern usage.
Symptoms
- Pressure drops significantly when multiple fixtures run
- Home has 1/2” main supply line (modern standard is 3/4” or 1”)
- Problem has always existed since you moved in
The Fix
Upgrading the main supply line from the meter to your home. This requires:
- Excavation
- New pipe installation
- Possible meter upgrade
- Permits and inspections
Cost: $1,500-$5,000 depending on distance and obstacles
When to Call a Plumber
DIY-appropriate situations:
- Cleaning aerators and showerheads
- Checking and opening valves
- Flushing water heater (if comfortable)
Call a plumber for:
- Pressure regulator issues
- Suspected pipe corrosion
- Hidden leaks
- Water heater problems beyond basic maintenance
- Main line issues
- Any situation you’re not comfortable handling
Pressure Booster Pumps: A Solution for Chronic Low Pressure
If you’ve addressed all fixable causes and still have low pressure, a booster pump may help.
How They Work
A booster pump increases pressure from the municipal supply before it enters your home’s plumbing.
When They’re Appropriate
- Municipal pressure is consistently low
- Home is at high elevation relative to water source
- Long distance from water main
- Large home with high demand
Cost
- Pump and installation: $300-$800
- Higher-capacity systems: $1,000-$2,000
Considerations
- Requires electrical connection
- Needs periodic maintenance
- May void warranty if pressure exceeds pipe ratings
- Won’t help if the problem is internal corrosion
Key Takeaways
- Start simple: Check aerators and valves before assuming major problems
- Diagnose the scope: One fixture vs. whole house tells you a lot
- Hot vs. cold: Helps pinpoint the problem location
- Age matters: Older homes with original plumbing are prone to corrosion
- Check with neighbors: Rules out municipal issues
- Know your limits: Some fixes require professional expertise
Need help with water pressure problems? Find local Chattanooga plumbers who can diagnose and fix your low water pressure issues.