Usually, poor water pressure is caused by clogged pipes. But if you've already replaced them or have a newer house with new pipes, try the obvious first. Make sure the shutoff valves near the water meter are fully open. Sounds basic, but plumbers still have to charge for a service call to simply turn a valve handle! Then check the water pressure. If your house is on city water, ask your local water department for a pressure reading. A reading of 45 to 55 psi is ideal.
Or test the water pressure yourself with a pressure gauge (sold at home centers). Hook up the gauge to an outside water spigot, turn on the water, and you'll get an instant reading. If the reading is low, the city may be delivering water at a low pressure (less than 40 psi). If the city isn't likely to boost the pressure, consider installing a water pressure booster system, starting at $300 at a home center or plumbing store, or online. Any setting over 80 psi will wear out the washers on your plumbing fixtures. The system we show is only made to fit 1-in. pipe. If you install it yourself, apply for a plumbing permit so your work will be inspected. Some municipalities require a reduced pressure and backflow preventer to be installed when a water pressure booster is hooked up.
If the pressure reading is adequate, you may have obstructions or some pipes that are too small. Call in a licensed plumber to evaluate your system.
If your water department can’t deliver more pressure and you have a 3/4-in. or bigger copper or plastic water main coming into your house, consider installing a water pressure booster. It takes the water coming in from the street and increases its pressure by means of an electric pump and a pressure tank. A dial on top adjusts the pressure to an ideal setting of 45 to 55 psi. The tank holds a reserve of pressurized water so that the pump doesn’t have to run every time somebody opens a faucet. It also helps boost flow when the demand for water is high (like when your teenagers are all showering at the same time). Water pressure boosters like the one shown here are available at home centers and online for about $900.
If your pressure test reads lower than 40 psi, see if you have a pressure-reducing valve (PRV) mounted on your water main. It’ll look similar to the one pictured here, and it needs to be adjusted correctly. Most come set from the factory for 50 psi, but you can adjust them up or down by turning a screw on top. PRVs can also go bad after 10 to 20 years and cause too little (or too much) pressure. So if yours is old, it might be time to replace it. Just about any DIYer with a little plumbing experience can handle the job. A new PRV will cost you $35 to $120, and you might have to special-order it.
If after all that you’ve still got low water pressure, call your local water department to see if there’s a problem with the pressure coming from the street to your house. If you get your water from a private well, your well pump might be the cause of your pressure woes.
When it comes to water pressure, you actually can have too much of a good thing. Pressure over 80 psi can cause you to waste water and the energy required to heat it. It can also damage water softeners, water heaters, faucets, appliances and seals. If your pressure test shows more than 80 psi, make sure you have a working pressure-reducing valve and keep it set between 50 and 60 psi.