The Homeowner’s Guide to Water Pressure

Standard Water Pressure Gauge
Photo Credit: Thomas Quine

Many plumbing problems in your home originate with water pressure issues. This may lead to low-pressure showers and toilet flushing issues on one end and damaged pipes or appliances on the other. Checking the water pressure yourself is not difficult, and may help you to identify potential problems before they become costly.

Standard Water Pressure

Recommended Water Pressure
Depending upon where you live, the water pressure could vary greatly as it comes in from the municipal supply lines. This can create problems, as the psi rating may range from 20 to as high as 100. The incoming water pressure should never be over 75 psi. Many plumbing professionals suggest 50 psi as the ideal, which is also the default setting for most pressure regulators.

Larger homes require a higher incoming pressure rating than small homes, as water will slow down slightly each time it encounters a bend in the pipes.

How to Test Water Pressure

The easiest way to check your home’s water pressure is to test the incoming pressure from the municipal lines.

  1. Locate the first faucet along the incoming water line. This faucet has the highest pressure and will tell you if any pressure issues are in your home or originate in the municipal lines.
  2. Make sure there is no water being used in the house. You may wish to use individual shut-off valves for faucets or toilets if you plan to exclude those from the test.
  3. Close the main shut-off valve.
  4. Attach a water pressure gauge to the faucet.
  5. Turn on the faucet completely to get a reading of the pressure.

You may test other faucets in the home using the same method to help locate pressure issues within the home itself once you have an idea of the initial pressure rating. This is especially useful for cases where you need to have a plumber check the pipes, as it provides a much smaller area to search for the source of your pressure problem.

Existing Plumbing Pressure Test

It is relatively easy to test your plumbing for problems using a water pressure test. An alternative is to test using air, although this is generally reserved for new plumbing. You will need an air compressor and an adaptor to connect the compressor hose to a threaded faucet. To test using air pressure, you will need to do the following:

  1. Locate the main shut-off valve and turn off the water supply.
  2. Run your faucets to drain the pipes and make sure all are turned off again once the pipes are empty.
  3. Attach a pressure gauge to a threaded faucet. This might be one in your laundry room or outdoors.
  4. Attach an adaptor to another faucet and connect your compressor hose.
  5. Charge the system to a rating of 60 psi and wait 15 minutes.
  6. Check to ensure the pressure has not dropped (indicating a leak) before turning the water back on.

New Plumbing Pressure Test

Testing new plumbing using air is more complicated than testing existing plumbing, although it can be much more effective. You will need some test balloons and test weenies, which are inflatable devices with pressure gauges attached. Test kits may be purchased, or you may choose to purchase the individual components from a hardware store.

  1. Block all drains, vent pipe fittings (commonly known as DWV lines) and toilet flanges using the inflatable test balloons. You will want to insert them into the T-fittings before inflating.
  2. Glue test caps to the end of all stub-out pipes. These are pipes which protrude from the walls or floor for later fittings to be attached, such as a shower head.
  3. Locate a clean-out fitting and inset a test weenie. Be sure the gauge is upright and easily readable before inflating.
  4. Bring the pressure within the pipes to five psi and wait 15 minutes, checking occasionally for any changes in pressure.

If a leak is suspected, you may use colored smoke or listen to the pipes for hissing sounds that may show a leak. Alternatively, you can place a little diluted dish soap on the joints and watch for air bubbles to appear.

Low Water Pressure

Dripping Water Faucet
© alexandrink1966 / Fotolia

Low pressure can be quite frustrating. Not only will it make your faucets trickle and slow down your washer, it can also lead to issues with your toilet or be an indication of a major problem. Thankfully, low pressure is often easy to diagnose and treat without having to call for professional assistance.

What Causes Low Water Pressure?

There are many potential reasons for low pressure many of which are easy fixes. Here are some of the more common problems:

  • Single Faucet – This is often caused by debris in the filter screen. There is usually one located at the end of the tap and sometimes another inside the base. Simply rinse and wipe out the debris, and it should improve the water flow immediately.
  • Shut-Off Valves – A common culprit of low pressure, there is a main shut-off valve for the entire home as well as ones leading into your toilets, sinks, etc. If not fully opened, they can restrict the flow of water, reducing pressure.
  • Pressure Reduction Valve – Some municipalities supply water in high pressures, and your home may have a pressure reduction valve installed to limit the incoming water pressure. The factory default is usually 50 psi, but may have been set lower by a previous owner or is simply too low to properly supply a larger home. Adjusting the settings will often alleviate the problem.
  • Leaks – Low pressure can be a sign of leaky pipes. Perform a pressure test and watch the gauge for signs of a leak. If the pressure changes, you may need to hire a professional to locate and repair the damage pipe.

How to Increase Low Municipal Water Pressure

In some cases, you may discover that the water pressure is low due to the municipal lines. Such problems usually also affect your neighbors and will require the installation of a water pressure booster. This device consists of a pump and pressure tank and is installed near the water meter.

A dial allows you to adjust the pressure between 45 and 55 psi, while the tank stores extra pressurized water to reduce how often the pump must run. Pressure booster systems may be an expensive investment, often running $900 or more, but it may be the only solution to low municipal pressure.

High Water Pressure

High Pressure Water Bursting Pipe
© iredding01 / Fotolia

While low water pressure is a nuisance, high pressure can be a nightmare. It can lead to burst pipes, leaks, burst boilers or water tanks, and associated problems such as flooding or mold. There are several warning signs of high water pressure, and you should test the psi rating if you encounter these:

  • Turning a faucet on or off causes banging or other noises to come from the pipes.
  • Spitting and leaks coming from faucets.
  • Toilets sometimes run when not in use.
  • Higher water or sewage bills without increasing water consumption.

The latter sign occurs because more water is used in the same amount of time as lower pressure pipes. Thus, running a tap while you water pressure has a rating of 150 psi may be using two to three times the amount of water it would if the pressure only rate 50 psi.

What Causes High Water Pressure

The most common cause of high water pressure is the municipal supply. Depending upon the requirements in your area, the water company may need to deliver water at a high pressure rating. This is especially true where they need to service tall buildings or areas high above sea level.

Another possible cause is thermal expansion. High temperatures in your home may contribute to heating up the water pipes to a small degree. Additionally, your water heater will cause the water to expand slightly. The hotter the water, the more pressure it will exert on the pipes. For this reason, it is always best to keep your water heater set at a low to moderate temperature setting.

How to Decrease Water Pressure

When faced with high municipal water pressure, the best solution is to install a pressure reduction valve. This valve connects where the water enters your home and reduces the incoming pressure. It is generally factory set to 50 psi, although you may adjust the pressure setting to allow for a higher psi rating.

Posted on Categories Plumbing