Water Pressure Testing

Water pressure may be one of the most misunderstood terms in plumbing.  It seems that whenever a faucet is turned on, and the water comes out as a dribble, the first thing people say is, “My faucet has low water pressure”.  While this may be true for an entire home, it is certainly not true for a faucet.  At least, not unless another fixture is on at the moment.

In the example above, the most likely case is a lack of flow, not pressure.  We will explore this in a little more detail in this article, as well as how to test your pressure.

How Water Pressure Works

Water pressure is, as the term implies, the amount of pressure behind water, forcing it towards its exit point.  It is measured by pounds per inch (PSI).  There are a few ways pressure is created, but the most common are from gravity, and pumps.

Pumps are pretty obvious, but gravity?  Water has mass, and gravity converts mass into weight.  This means that if you fill a vertical tube full of water, the weight of the water above it creates pressure on the bottom.  If you had an outlet, with a gauge, towards the top and towards the bottom, you could measure the difference in pressure.

Another factoid is that as water is forced to exit via a smaller pipe, the pressure actually increases.  An easy example of that is an aerator.  If you take the aerator off of a faucet, and run the water, the water will come out faster, but appear to come out slower.  Putting the aerator back on, forces the water to flow through smaller holes, which decreases the flow rate of the water, but actually increases the effective pressure.

Why is this important?  Well, when you think of the relatively few things that can affect water pressure, and the fact that smaller pipe diameters actually increase the effective pressure, it is easier to understand that the pressure to your home, is the pressure to your home… all the faucets… everything.

How to Do a Water Pressure Test

Step 1 – The easiest way to start testing your water pressure is at the hose bib, right next to your water main.  There is usually a hose bib tied right into your main.  Most hardware and home improvement stores will have a pressure gauge that screws onto a hose bib that you can pick up on the cheap.  Just screw it on, and open the hose bib, and you will get a pressure reading.  That is the “static” pressure in PSI. Write it down.

Step 2 – Open up a water faucet somewhere in your home, and come back and read the gauge again.  Unless you have a pressure regulator, the PSI should have dropped.  If you have a pressure regulator, and it still dropped, you most likely have a faulty regulator.

Step 3 – Turn off the faucet, and go to a hose bib at the very opposite side of your home from the water main bib, and take a reading there.  The pressure should be the same as the first reading.  If it is not, you have something in your home, relieving pressure somewhere.  That is usually a leak.

So Now What?

Back to the faucet example.  While there are relatively few ways we can impact pressure, there are many ways to reduce flow.  From a clogged aerator, to an old galvanized pipe that has rusted almost shut, there is a completely different procedure for determining what and where that problem is caused.

Remember, the proper reading for your water pressure test is between 55 and 65 PSI.  Anything lower than that and you either have a faulty regulator, or it is a problem with the municipal supply to your home (or a problem with your well).

Any higher than that, and you either need a regulator installed, or your existing regulator adjusted or replaced.  Whatever is going on, be it flow or pressure… too high, or too low… you can count on Gogo Rooter Plumbing to be on the spot, with exactly what you need to make it right.

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