Low water pressure in the house

When I moved into my current house the house inspector said that the water pressure, measured outside at 70 psi, was sufficient to run 2 showers simultaneously. However, the flow rate at the faucet is pretty poor and certainly is not adequate. My question is how do I check and adjust the pressure in the house and to what level should I adjust the pressure?

Well, you need to think a little about this...there is a relationship between pressure and volume, but to get a decent shower, you need both. Think about a squirt gun...lots of pressure (shoots far), but no volume. If the house is old, it may have galvanized pipes that are essentially so small, they are like a soda straw inside. They can give you wonderful pressure, but no volume. Sort of like you turning the water hose faucet on to a trickle, then putting your thumb over the end - you'll create a stream with great pressure, but again, no volume. So, you need to do some investigation - it may be time to repipe the house...copper or pex might be in your future to solve this problem. Course, it could be as simple as the house shutoff valve is not open all the way, too.

The house is not very old, it is copper piped and has recently had a new water heater fitted. I suspect that the PRV has never been set correctly but am unsure how to adjust it and how to check the water pressure in the house so that I don't set it to the wrong level, what ever that may be.

Get a Pressure Gauge

First, find out if there is a regulator or Pressure Reducing Valve (PRV). If there is one it should be near the water meter, inside after the meter. If there is no PRV then you don't have anything to adjust.

If you have something to adjust, then you need a pressure gauge. They have some that connect to a faucet. Check Home Depot.

Put the pressure gauge on a faucet and open another faucet to let a trickle of water flow. I don't like to adjust things with no flow.

The top of the PRV will usually have something that looks like a bolt sticking out the top. It may have a square head or a screwdriver slot. There will also usually be a nut down against the bonnet of the PRV. The nut is a lock nut. The bonnet of the PRV often is shaped like a bell.

Loosen the locknut slightly (maybe 1/4 turn or so) so that you can turn the bolt sticking out the top. Screwing it in (clockwise looking at it) usually increases the pressure. Have someone look at the gauge while you adjust it. After you set the pressure, hold the pressure adjusting bolt with a wrench while you tighten the locknut.

If you are successful, start with increasing it to 60 psi and see if you like the result. If you have to get to more than 60 psi you probably have other problems.

You can do some tests to check the points that jadnashua made. Get a large bucket and measure the volume (how many pints with your wife's measuring cup? 8 pints to a gallon). Then measure the time (seconds) it takes to fill the bucket at various places, including any outside faucet and the bathtubs. Calculate Gallons per Minute. Bathtubs, outside faucets, and laundry sinks usually have little restriction. Put the pressure gauge on a faucet that is nearest the water meter to see if you are getting losses in the supply pressure when you open the faucet or bathtub farthest away from the meter.

If you are maintaining good pressure near the inlet, then it means that your problem is probably in the pipes to the shower, or in the shower head. The low flow showers are not always very satisfying.

If both showers are run off the same small line, you may need to run a bigger line to the showers. The usual 1/2" copper may be too small to serve two showers at the same time.

Thanks for the information. I appreciate the help you have given me.