How to Fix Low Water Pressure

Turn on faucets throughout the house one at a time — kitchen, bathrooms, laundry, outdoor hose bibs. Note which fixtures have low pressure. If only one faucet is affected, the problem is at that fixture (likely a clogged aerator). If an entire bathroom is low, check the shut-off valves for that room. If the whole house is low, the issue is the main supply — move to step 4.

The aerator is the screened tip screwed onto the end of the faucet spout. Unscrew it by hand or with pliers (wrap the jaws in tape to avoid scratching the finish). Disassemble the aerator — you'll find a screen, a flow restrictor, and gaskets. Soak all parts in white vinegar for 30 minutes to dissolve mineral deposits. Scrub the screen with a toothbrush. Reassemble and screw it back on. If the screen is badly corroded, buy a new aerator for $3-$5.

Locate every shut-off valve in the affected area — under sinks, behind toilets, and at the water heater. All valves should be fully open (turned counterclockwise until they stop). Gate valves (round handles) are especially notorious for being left partially closed after repairs. A valve that's only 50% open dramatically reduces water flow. Also check the main shut-off valve where water enters the house.

Screw a water pressure gauge ($10 at any hardware store) onto an outdoor hose bib or the laundry faucet. Turn the faucet on fully with no other fixtures running. Normal household pressure is 40-60 PSI. Below 40 PSI is low. Above 80 PSI is too high (and can damage plumbing). If pressure at the gauge is normal but fixtures are slow, the problem is internal (clogged pipes or fixtures). If the gauge reads low, move to the next step.

Many homes have a pressure-reducing valve (PRV) or pressure regulator on the main water line, usually near the meter or where the line enters the house. It looks like a bell-shaped brass fitting with an adjustable screw on top. Turn the adjustment screw clockwise to increase pressure (small turns — 1/4 turn at a time, then re-test). If adjusting doesn't help, the regulator may have failed and needs replacement — a $25-$50 part.

If only hot water pressure is low, mineral sediment may have built up in the water heater tank, restricting the hot water outlet. Turn off the heater (gas or electric). Connect a garden hose to the drain valve at the bottom of the tank and run it to a floor drain or outside. Open the drain valve and let water flow until it runs clear. Close the valve, refill the tank, and restart the heater. This should restore hot water flow.

If your home has galvanized steel pipes (gray metal, common in homes built before 1970), internal corrosion may be restricting flow. Look at exposed pipes in the basement or crawl space. If the pipes appear rusty or have mineral buildup at joints, the internal diameter is likely narrowed. Unfortunately, the only permanent fix for corroded galvanized pipes is re-piping with copper or PEX — a professional job that costs $2,000-$5,000.