Robert Pelikan writes that one alternative method of providing your customers with constant pressure while extending the life of their pump is to add a constant pressure valve to a conventional water system.
During the last several years, much has been written about constant pressure systems. Most of the information has come from the manufacturers of pump systems with variable speed motors. These systems can provide constant water pressure over a fairly broad range of flow rates by electronically changing the speed of the motor, as the demand changes, to keep the pressure constant. The advantages to the end users include the elimination of annoying pressure fluctuations in their homes and an increase of motor life by reducing the number of damaging on/off cycles. Additionally, these systems may allow the use of a smaller pressure tank if space is a problem. And finally, they likely will reduce the amount of electricity used by the pump because of the affinity law, which states, "The amount of horsepower drawn by a pump motor varies by the cube of its speed."
However, variable speed systems do not come without baggage. Some are noisy, both audibly and electrically, the latter possibly effecting a neighbor's television reception. Reliability hasn't been what it should have been, and if they do break, "repair" often means replace since the problem area usually involves the electronic circuitry. Simple fixes like cleaning the bugs out of the pressure switch or filing down the points don't hack it with these systems. You will need a different set of spares on your service truck and perhaps a different service man. Even with these shortcomings, some dealers swear by these systems, so if you are the adventuresome type, jump in. Just keep your eyes open.