My water pressure is only about 25 PSI both inside and outside. The water district told me they are supplying 115 PSI to the house and advised that my Pressure Release Valve (PRV) is probably broken. The problem is, I can't find it. It's supposed to be within 5 feet of my water meter, which is buried outside near the curb, about 20 feet from the house. The water district can't help me find it. It doesn't seem to be near the clean-out for my sewer lines. Any suggestions how to find the valve?
Your pressure relief valve (let's stop using acronyms) is probably located on your water heater, it is actually a temperature/pressure relief valve. Sometimes a "pressure only" relief valve will be located on supply piping also. They are designed to open up and relieve pressure due to an unplanned temporary high pressure event, they both look something like this:
A pressure regulator is different. It is designed to regulate (control) your water utility company pressure before that pressure can damage your plumbing. This is the device you need go find. It should look something like this:
You will notice by a close look at the pictures that these two valves look very different.
It is not your pressure relief valve (PRV), the PRV is there to protect your system from high pressure. It's not installed "in-line" where it could affect your water pressure unless it was open. When it opens it releases to atmosphere (or maybe a drain) but you would know because either you would see/hear water or have an astronomically high water bill.
What you should look for is a pressure regulator, which regulates the pressure delivered downstream. These are often located outside on the supply piping upstream of your house and most often have a pre-set delivery pressure (although the pressure on most can be manually adjusted). The regulator is also there to protect your home from high pressure.
Where I live, the water meters are out by the frontal property boundary and these regulators are never located there. They are most often close to the house near the point where the incoming water pipe enters.