Quick Answer: Low water pressure is usually caused by a clogged aerator, a partially closed shutoff valve, corroded galvanized supply pipes, mineral buildup from hard water, or a leak somewhere in the supply line. Start by checking the aerators on affected faucets and confirming the main shutoff valve is fully open. If pressure is low throughout the entire house, the problem is likely in the main supply line or the pipes themselves, and a licensed plumber should assess the system.
Single Fixture vs. Whole House: Where to Start
The first question is whether the low pressure affects one fixture or every fixture in the home. That distinction tells you almost everything about where the problem lives.
If only one faucet has low pressure, the cause is almost always at that fixture: a clogged aerator, a partially closed supply valve under the sink, or a kinked flexible supply hose. These are simple fixes that most homeowners can handle without a service call.
If pressure is low throughout the house, the issue is upstream. It’s in the main supply line, the meter connection, or the distribution pipes running through the walls. That requires a plumber.
Check 1: Faucet Aerators
Every faucet has an aerator screwed onto the tip that mixes air into the water stream. In Asheville, where the water hardness runs around 8 grains per gallon, these aerators clog with mineral deposits faster than homes with softer water.
Unscrew the aerator (most twist off by hand or with pliers and a cloth for grip), rinse the screen, soak it in white vinegar for 30 minutes, and reinstall. If the pressure returns to normal, you found the problem.
This should be part of routine maintenance in any Asheville home. Cleaning aerators every 3 to 6 months prevents the gradual pressure loss that many homeowners don’t notice until it becomes significant.
Check 2: Shutoff Valves
Your home has a main shutoff valve where the supply line enters the house, plus individual shutoff valves under every sink and behind every toilet. If any of these are partially closed, pressure to that fixture or the entire house will be reduced.
After any plumbing repair, water heater service, or municipal water main work, valves sometimes get left partially closed. Walk through the house and verify every valve is fully open. The main shutoff should turn counterclockwise until it stops (gate valve) or align parallel with the pipe (ball valve).
Check 3: Pressure Regulator
Some Asheville homes, particularly those at lower elevations or near the bottom of the municipal pressure zone, have a pressure reducing valve (PRV) installed on the main supply line. If the PRV fails or goes out of adjustment, it can restrict flow to the entire house.
A functioning PRV typically maintains household pressure between 40 and 60 PSI. If your pressure has dropped across all fixtures and you have a PRV, it may need adjustment or replacement. This is a job for a licensed plumber because incorrect adjustment can create dangerously high pressure that damages pipes and fixtures.
Check 4: Corroded or Restricted Supply Pipes
This is the most common cause of whole-house low pressure in older Asheville homes. Galvanized steel supply pipes, standard in homes built before the 1970s, corrode from the inside over decades. The pipe exterior may look fine while the interior has narrowed to a fraction of its original diameter.
Asheville’s hard water accelerates this process by layering mineral scale on top of the corrosion. The result is a pipe that simply cannot deliver the volume of water your fixtures need.
If your home has galvanized supply pipes and you’ve ruled out other causes, repiping is likely the permanent solution. Modern PEX or copper supply lines restore full pressure and last decades without the corrosion issues that galvanized steel creates.
Check 5: Hidden Supply Line Leak
A leak in the main supply line between the meter and the house reduces pressure by diverting water before it reaches your fixtures. Signs of a hidden supply line leak include an unexplained increase in your water bill, a wet or unusually soft spot in the yard between the meter and the house, and pressure that fluctuates without any change in usage inside the home.
If you suspect a supply line leak, check your water meter. Turn off every fixture and appliance in the house, then watch the meter dial. If it’s still moving, water is leaving the system somewhere it shouldn’t be.
Check 6: Municipal Supply Issue
Occasionally, low pressure isn’t caused by anything in your home. The City of Asheville’s water system may be performing main line repairs, flushing hydrants, or dealing with a pressure zone issue that temporarily reduces supply to your area.
If your pressure dropped suddenly and neighbors are experiencing the same thing, check with the city before scheduling a plumber. If it’s only your home, the problem is on your side of the meter.
When Low Pressure Means a Bigger Problem
Persistent low water pressure combined with water heater performance issues often signals a system that’s reached the end of its useful life. Your water heater can’t heat water efficiently when supply pressure is low, and the sediment from hard water compounds the problem in both systems simultaneously.
If you’re dealing with low pressure and your water heater is showing age, addressing both as a coordinated project is more cost-effective than fixing them separately.
Get Your Pressure Diagnosed Properly
Sudo Plumbing, LLC provides pressure testing, supply line assessment, and repiping services across Asheville, Weaverville, Arden, Leicester, Candler, Swannanoa, Black Mountain, Woodfin, and Fairview. Free in-person estimates and flat-rate pricing on every job.
Call Sudo Plumbing, LLC: (828) 676-8772
FAQs About Low Water Pressure
Why is my water pressure low in only one bathroom?
If pressure is low at just one fixture or one bathroom, the cause is usually a clogged aerator, a partially closed shutoff valve, or a restricted supply hose under the sink. Check those three things first before calling a plumber.
Can hard water cause low water pressure?
Yes. Hard water deposits mineral scale inside pipes, gradually reducing the interior diameter and restricting flow. Asheville’s water hardness of around 8 grains per gallon makes this a common issue, especially in homes with galvanized steel supply lines.
How do I know if I need a whole-home repipe?
If you have galvanized steel pipes, low pressure at multiple fixtures, and the home is more than 40 years old, a whole-home repipe is likely the permanent fix. A plumber can confirm by inspecting pipe condition and testing pressure at multiple points.
Should I call a plumber or the city for low water pressure?
Check with your neighbors first. If they have the same issue, it may be a municipal supply problem. If the low pressure is only at your home, the issue is on your side of the meter and a licensed plumber should assess it.
