Are the valves partially closed?
This is the easiest possible solution for low water pressure. Start my making sure the shut-off valve on your main water supply is completely open. These valves are often found right where plumbing enters the house. You may also find valves at the cold water inlet for your water heater. You may find one of two common types: the gate valve or the ball valve.
A ball valve has a long handle that indicates the position of a small ball diverter inside the pipe. If the handle is lined up with the pipe, water is flowing freely. If it's turned 90 degrees, water is completely shut off. Any position of the handle between this will restrict the flow of water.
Gate valves have a rotary handle that determines the position of a small gate inside the pipe. Turning the valve clockwise will close this gate and stop the flow of water. The valve needs to be turned all the way to the left to pen the gate fully.
Is it the PRV?
Many homes have a pressure reducing valve (PRV) or a backflow preventer installed. A PRV has a number of small parts that regulate water pressure going into your home and these parts can fail over time, causing the flow of water in your home to become restricted. Before disassembling the valve, make sure you water is completely turned off. If your PRV is installed before the main shut off, you'll need to have the water turned off at the meter first. Many times these parts become corroded and require complete replacement. While you can do this job yourself, you may want to hire a qualified plumber.
Are the pipes corroded?
Steel and galvanized pipes often start to clog with mineral build-ups or become corroded after about 20 years. There is no way to fix this problem without replacing the piping. Unfortunately, this is an expensive and very time-intensive job that requires a professional. Most of the time, houses with internally corroded pipes have full flow fixtures in the home so flow restrictors and aerators installed on shower heads and facuets may appear to help the problem while you're showering or using the sink.
If you suspect corroded pipes or a failed PRV, contact the professionals at Inland Empire Plumbing right away to get the problem taken care of before it gets worse.