During a home inspection, a competent inspector will measure and report on the water delivery pressure. Water pressure is determined by the water supplier and can fluctuate. Sometimes the pressure is elevated to serve an eventual demand on the supplier's system when all the homes in an area are completed. In any case, high water pressure is not a good thing.

Most people think of water pressure as what they experience when they use the sink or take a shower. This is not an accurate use of the term water pressure. What you experience at a fixture is actually called flow rate. Flow rate is a combination of the water pressure, the interior condition and diameter of the piping, the length of the piping run and the number/type of elbows. All these factors determine what you experience at each tap. Water pressure, by contrast, is static. Water pressure is the same throughout the building piping system.

By code, a home MUST have a regulator installed if the delivery pressure is above 80 psi. Based on my experience in the field, I do not think the municipal inspectors use a pressure gauge when they inspect a home during construction. Excessive water pressure is epidemic in the Phoenix metropolitan area. Homeowners often think that they don't have a problem because the flow rate seems very normal or maybe even low. That is often because modern fixtures have flow restrictors on them that regulate the flow. Most homeowners are shocked to hear that they have excessive water pressure.

What is the effect of excessive water pressure (anything over 80 psi)? Elevated risk of leaking anywhere in the system. That may include piping under the slab, piping inside walls, the clothes washer hoses, etc. -- does the term "moisture damage" come to mind.

What can be done about the problem? Check the water pressure. A gauge can be purchased at many hardware stores. If the pressure exceeds 80 psi, contact a competent plumber to install a pressure regulator. The cost will likely be $200 to $250 but may save many times that later. Also, it is a good idea to install reinforced (braided stainless steel) flex lines at the clothes washer, toilets and sinks. Low quality flex lines are the weak link in a home's plumbing system. Be proactive - check your pressure.