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I had my house renovated about 5 years ago and was told at the time that I have high water pressure and may need a pressure limiting valve. Fast forward to now and have one tap (5 years old) that has worn out and whose top literally flies off when the tap is opened too fast. My now 5 year old hot water service overflow value has worn out and is now leaking constantly.

Are these signs that the water pressure is too high. Turning the taps on always gives a lot of water, the shower is never affected by other taps.

Before I replace the tap and HWS value, i'd like to know if I should be installing a pressure limiting valve first.

How do you (or a plumber) test for high water pressure? What should it be?

BTW: none of the pipes knock if that helps.

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    Can you get a pressure gauge? – ThreePhaseEel Oct 10 '16 at 2:34
  • @ThreePhaseEel - I don't have one. Didn't even know that they existed. A quick look shows they are quick cheap ($18 AUD). What pressure is "good?" – dave Oct 10 '16 at 5:33
  • A pressure regulator on the incoming main is what you need this will limit the pressure to the value you adjust it to an inexpensive gauge on the regulator will show the actual output pressure. The regulator needs to be sized to your main line. With a 1" main you want a regulator with 1" ports. something like this. – Ed Beal Oct 10 '16 at 9:05
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    @dave Between 40 and 80 PSI / 2.75-5.5 Bar / 275-550 kpa is the norm in the states. – Mister Tea Oct 10 '16 at 13:25
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Checking the pressure

Get yourself a two way hose connector (~$6), and a water pressure gauge that fits 3/4" garden hose thread (GHT) (~$10)

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Connect the pressure gauge to one of the legs of the wye connector, and turn the valve for that leg on. Connect the wye connector to a utility sink tap, or a hose bib. Turn the valve on the open leg of the wye connector off, and open the valve on the sink/bib.

At this point, the gauge should display the pressure within the plumbing system.

Open and close the valve on the wye connector, then check the gauge again. Do this a couple times, to make sure you're getting a consistent reading.

NOTE: When testing the pressure, you'll want to make sure the water heater is not actively heating the water. If it is, wait for it to finish before checking the pressure.

The International Plumbing Code says that the water pressure should be grater than 40 psi, but less than 60 psi. So you'll be looking for a pressure within that range. If it's above that, you'll have to take a closer look at the system.

Determine the cause

Depending on when your home was built/remodeled, there may be a check valve installed on the main supply line. If this is the case (should be with modern homes), then heating water can increase the pressure within the plumbing system. If there is a check valve installed, you'll want to make sure you have an expansion tank installed near the water heater. You'll also want to check to make sure the expansion tank is in good working order.

If all that checks out, the high pressure is likely due to high supply pressure. In this case, you'll want to install (or have installed) a pressure regulator on the main supply.

Once installed, you can use the pressure gauge setup from above, to adjust the regulator to the desired pressure.

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