Water pressure too low or is it low functional flow
When there doesn’t seem like enough water is coming out of a sink faucet, shower head or the sprinklers: we often say that the water pressure is too low. But in reality, it may not be the water pressure at all. It may be low functional flow.
Water pressure v. Functional flow
Water pressure is the amount of water pressure coming into the home from the city. It is measured in PSI (pounds per square inch). Normally inspectors like to see the water pressure to be between 40 and 80 psi.
To discover what the water pressure is at your home, ask your home inspector, have a plumber measure it, call the local water company and ask them, or simply get a $10 water pressure gauge from a local home improvement store, and hook it to a hose bib, turn the hose bib on, and see what the pressure is. It doesn’t matter what the size of the water line is, the pressure will be the same whether it’s a quarter inch water line or a 1 inch water line. However, the functional flow may be significantly different, depending on the water line size.
If the pressure is low, there are several things you can check and do.
First, check with the water department to see what the water pressure is in your area. They may have a pump down, may be working on the system or be planning on increasing the pressure in your area.
If the house has a pressure regulator, check to see if it is set too low and if it is working properly. Sometimes, just adjusting the pressure setting will solve the problem. Pressure regulators have a tendency to wear out or stop functioning properly after a number of years.
If the city pressure is too low, then adding a booster pump to your water system may help. This is usually done by a plumber.
Low functional flow
Low functional flow (not enough water flowing through your sink faucet, tub spout, or system)
First check the following:
If functional flow is low for the whole house, then check to see if the main valve at the meter is fully open and that the house shut off valve is fully open. They may only be partially open.
If functional flow is low at one or more fixtures, then check the small shut off valve going to the fixture. Sometimes called an angle stop. They may be only partially open.
Is the fixture a water conservation fixture, for they have a much lower flow rate than older ones. Is there an aerator on the end of the faucet that is clogged or needs cleaning?
In older homes it may be due to corrosion or rust build-up in the galvanized piping.
Occasionally it may be do to the water piping sizing or too many fixtures on one line or an obstruction in the water line.