Why Is My Water Pressure Low? 8 Common Causes and How to Fix Them
This article helps you figure out why your water pressure is low, whether the problem is inside your plumbing or coming from the supply line outside. Each cause comes with a fix or a clear next step, so you can tell whether it’s something you can handle yourself or whether you need to call a plumber or your water utility.
Common Causes of Low Water Pressure in Your House
1. Clogged Aerator or Fixture-Specific Blockage
Mineral deposits and debris build up in faucet aerators and showerhead screens over time, cutting off flow at one fixture while everything else in the house works fine. Fix: Unscrew the aerator or showerhead, soak it in white vinegar for 30 to 60 minutes, then rinse and reinstall. No tools needed.
2. Partially Closed Main Shutoff Valve or Water Meter Valve
If the main shutoff valve inside your home or the water meter valve at the street isn’t fully open, pressure drops throughout the whole house. This often happens after plumbing work when someone forgets to reopen a valve all the way. Fix: Find both valves and make sure they’re fully open. Ball valves should sit parallel to the pipe; gate valves should be turned fully counterclockwise. No tools required.
3. Faulty or Miscalibrated Pressure Regulating Valve (PRV)
A PRV controls the pressure coming into your home from the supply line. When it fails or goes out of calibration, pressure can drop throughout the whole house, sometimes suddenly. Fix: The PRV is usually near the main shutoff. You can test incoming pressure with a gauge (under $15 at most hardware stores), but adjusting or replacing a faulty PRV is a job for a licensed plumber.
4. Leaking Pipes, Including Hidden Leaks
A leak anywhere in your plumbing diverts water before it reaches your fixtures, which lowers pressure throughout the house or in one specific area. Leaks inside walls or under slabs are common and easy to miss. Fix: Look for unexplained wet spots, soft drywall, or a water meter that keeps running when all fixtures are off. If you suspect a hidden leak, call a plumber. Finding and fixing it is not a DIY job.
5. Clogged, Corroded, or Mineral-Deposit-Laden Pipes
In older homes, galvanized steel pipes corrode from the inside, and mineral buildup in any pipe type slowly narrows the interior, reducing flow over time. Fix: There’s no quick fix here. A plumber will need to assess whether sections of pipe can be descaled or whether repiping is the right call.
6. Water Heater Supply Issue
If low pressure only affects your hot water, the shutoff valve on the water heater may be partially closed, or sediment buildup inside the tank is restricting flow. Fix: Check that the shutoff valve on the cold-water inlet to the heater is fully open. If hot-side pressure is still low, flush the tank to clear sediment. If the tank is older and heavily scaled, call a plumber.
7. Municipal or Neighborhood Supply Issues
When low pressure is coming from the city supply line, it affects the whole house and there’s nothing you can do on your end. Main breaks, high-demand periods, or nearby infrastructure work can all cause temporary drops. Fix: Check whether your neighbors have the same problem. If they do, contact your water utility to report it and get an estimated fix time. There’s nothing to diagnose inside your home.
8. Well Pump, Pressure Tank, or Pressure Switch Failure
For homes on well water, low pressure usually points to the well pump losing output, a waterlogged pressure tank, or a pressure switch that’s no longer triggering the pump correctly. Fix: Check the pressure gauge on the tank. Normal range is typically 40 to 60 PSI. If it reads low or zero, check the circuit breaker for the pump first. After that, a well service professional should inspect the pump and pressure switch.
Why This List Covers What You Need
- The list covers both internal plumbing causes and external supply factors, so it applies no matter where the problem is coming from. You don’t need to know the source before you start.
- Every cause comes with a concrete next step, so you know what to do, not just what might be wrong.
- The list tells you inline which causes are DIY-friendly and which ones need a plumber or utility contact, so the decision is built right into the diagnosis.
Key Insights
- Causes 1 and 6 affect a single fixture or system, while causes 2, 3, 4, 5, 7, and 8 typically cause house-wide pressure drops. Where the problem shows up is the fastest way to narrow down the list.
- A partially closed valve or a clogged aerator requires no tools and can be checked in minutes. Corroded pipes, hidden leaks, and a failing well pump require a professional and can’t be self-resolved.
- Some causes, like a closed valve or a municipal supply disruption, show up suddenly. Others, like mineral buildup and pipe corrosion, develop gradually over months or years. That difference can help you narrow things down before any inspection.
Variations by Context
Municipal Supply Homes: Low pressure can originate outside your property entirely, at the street-level meter valve or from a supply issue affecting the whole neighborhood. Before you start checking things inside, see whether your neighbors have the same problem. If they do, call your water utility directly.
Well Water Systems: For homes on a well, the cause shifts significantly. Municipal supply issues don’t apply, and the most likely culprits are the well pump, pressure tank, or pressure switch. Aerator clogs and internal pipe issues still apply. Check the pressure gauge on the tank first before assuming the problem is inside the house.
When to Use This Guide
- Your water pressure is low throughout the entire house, not just at one fixture.
- Pressure is low at a single faucet or showerhead but normal everywhere else.
- Pressure dropped suddenly after recent plumbing work or a repair.
- Pressure has been declining gradually over a period of months.
Frequently Asked Questions
Q: Is low water pressure a whole-house problem or a single-fixture problem?
If pressure is low throughout the house, the cause is more likely a valve, pipe, regulator, or supply issue. If it’s limited to one fixture, a clogged aerator or localized blockage, both covered in the list, is the more likely explanation.
Q: How do I know if the problem is inside my home or coming from the street?
Start by checking whether your neighbors have the same pressure drop. If they do, the issue is likely on the utility side. Also make sure the water meter valve at the street is fully open, as covered under cause 2.
Q: Can I fix low water pressure myself, or do I need a plumber?
Some causes are straightforward DIY fixes. A partially closed valve or a clogged aerator can be resolved without tools or professional help. Others, including corroded pipes, hidden leaks, and a faulty pressure regulator, require a licensed plumber, as noted throughout the list.
Q: What if my water pressure dropped suddenly rather than gradually?
A sudden drop most commonly points to a partially closed valve, a pipe leak, or a municipal supply disruption, all covered in the list. Gradual pressure loss is more typical of mineral buildup or pipe corrosion, which develop slowly over time.
This article covers both internal plumbing causes and external supply factors, with each cause paired with a next step so you can tell whether the fix is something you can handle yourself or whether it requires a plumber or utility contact. Work through the list starting with the causes most relevant to where the pressure loss is showing up.