I got a call from a customer that she were having a problem with her plumbing: low water pressure. This is a common description from homeowners that is used generically for many different water problems. In this case, the homeowner was complaining about whenever she showered, if someone turned on a faucet, the water would dramatically decrease in the shower to the point that she couldn't shower until that faucet was turned off. We see this happen with pressure balancing anti-scald shower valves to avoid someone getting scalded if, for example, someone flushes the toilet. This type of valve intentionally lowers the hot water pressure to keep the temperature constant when there is a sudden draw of cold water. That wasn't the case with this though. The problem was uniform throughout the house, and not just isolated to that particular shower.
People often misuse the term low water pressure. In this case, the water pressure was fine. We put a water pressure gauge on the hose bib and the incoming pressure was nearly 75 psi. This is considered very strong water pressure. The problem here was the water volume. You can have strong water pressure but poor water volume. The result is a weak shower.
The first thing to check is the main water valves. In this case we went to the street and the water meter was turned on only about halfway, effectively cutting the water volume in half. Simply turning the valve all the way to the open position solved this customer's shower issue.
Had this not solved her volume problem, we would have done more investigating starting with the shut-off valve in the garage. It happened to be a gate valve which has a reputation for causing problems, such as the gate breaking off and partially or completely blocking the flow of water.
A realtor called us today to troubleshoot a plumbing problem. They represented a bank and turned the water on to the house, but water was not flowing into the house. I suspected that the shutoff valve in the garage was not functioning.
It's pretty common when you shut off the water to a house with an old gate valve, the gate that controls the flow of water will drop down and stop the water from flowing into the house. As long as the water is on and the pressure is maintained, the gate will typically stay in place.
To get the water flowing again, you will need to replace the valve, or at least pull the broken gate out of the valve. The quick fix is to pull the broken gate out of the valve. This means that in the future, in order to shut off the water to the house, instead of turning it off at the gate valve, you will need to turn it off at the street. That probably isn't a big deal to most people.
So turn the water off at the street and put a wrench on the top half of the gate valve. The top will come off in one piece. Then reach down into the lower half of the valve and pull the broken gate out. Put everything back together and turn the water back on at the street.
There are many times a frustrated homeowner will call needing some type of faucet repair for low pressure.
This is one of those cases where you have to isolate the problem. Yes, you might end up having the faucet replaced, or a valve, or a cartridge, or a stem, etc. You're thinking big dollar signs now right? Well I would ask you some questions before I started to worry (this quick fix will typically solve 90% of low-pressure problems in bath faucets).
Here's how the dialog usually goes: (and I will be interrupted many times throughout the conversation...please, just the facts, Ma'am)
Me: "Is the problem isolated to this particular faucet?"
Caller: "Yes, but"...
Me: "Do you notice low pressure at both the hot side and the cold side when they are turned on separately?"
Caller: "Yes, but"...
Me: "Try removing the aerator to see if that makes a difference".
Caller: "The what?"
Me: "The aerator. It's that thingy at the end of your faucet's spout where the water actually comes out".
Caller: "OK, how do I get it out?"
Me: "You grab it with your fingers and unscrew it"
Caller: "That's it?"
Me: "That's it"
Actually, removing the aerator is only half the battle. Then it is going to take you another 5 seconds to clean out the gunk caught in the screen, and an additional 2.7 seconds to screw it back into the faucet.
Now some people will want to make a project of cleaning the aerator. Just dump out the debris and maybe poke out the gunk in the screen with a pin. If you want to get really fancy, you can soak it in vinegar or CLR. Heck, go crazy and lay out $2 for a new one. It's up to you.