Unless you’re a plumber, a water pressure test gauge probably isn’t something you’d ever use — unless you had suspicions that the water pressure in your house was too high or too low. It sure wasn’t on the list of tools I thought I’d ever need, that is until I started looking into replacing our kitchen faucet.
Our kitchen faucet is getting pretty dated. I know it’s not the original from the 70’s, because the cabinets have been replaced, but I suspect it’s probably from the 80’s. That’s why I was a little concerned that I only was getting 1.7 gpm flowing out of the tap. Modern kitchen faucets are usually 1.5 to 1.8 gpm (with an occasional 2.0 or even 2.2 gpm). These gpm ratings are usually spec’d at a water pressure of 60 psi.
Because I figured a faucet that old would surely have a higher flow rate, I was afraid that my water pressure was much less than 60 psi and that instead of getting 1.8 gpm out of a new faucet, I’d get something much less. Buying a new faucet and having it be less useful than my old one would be disappointing
I know they have started restricting flow from faucets to conserve water, but the one area where I think it makes the least amount of sense is the kitchen sink. If you fill the sink for dishes, or a pot to put on the stove, having to wait substantially longer can be frustrating.
While in Home Depot the other day, I found the Watts Water Pressure Test Gauge, model IWTG. This pressure gauge attaches to a standard 3/4″ hose fitting and reads from 0 to 200 psi.
Watts says you can attach the gauge to either a hose bib or your water heater drain, but a more useful place may be your washing machine hookups.
It features a 2-1/2″ dial with 2 indicators: a black one to show actual pressure, and red for max pressure.
The sensing element is a copper alloy Bourdon tube with ASME, Type B40.100 accuracy. Unfortunately, if you want to know what that officially means, you need to shell out $125. But after a little free research, I found it just means the accuracy is somewhere in the range of ±2% to ±3% of the span.
This little gauge will run you $10 at Amazon and Home Depot. You should be able to find it at plenty of other places too.
At first I found the max pressure indicator to be utterly useless. Turning on the faucet normally pegged it all the way around. If I very slowly and carefully turned on the faucet it matched the real-time house water pressure, but then I thought, “wait, I wonder what happens if I turn a faucet on and off somewhere else in the house?”
Viola, you get the surge pressure. This could be handy for figuring out if you need to install a water hammer suppressor or just secure your pipes if they bang when turning on the washing machine. The description of the product also says you can use it to detect thermal expansion pressure surges.
If you are curious how to measure the flow rate, it’s pretty simple. You don’t need any special equipment, just a vessel with a known volume and a stopwatch. For instance I used a gallon milk jug to make the calculations easy.
To measure the flow rate, turn the tap on full, start the timer when you start filling the container. Then stop the stopwatch when the container is full. In my case I was filling the gallon milk jug in 35 seconds. To find my flow rate, I just divided the time into 60 seconds (60/35) to get 1.7 gpm.