I have a tri-plex that has new copper water pipes. 1" feed into the house and to each floor, 3/4" pipes for all horizontal runs and 1/2" pipes in the walls. The whirlpool tub on the first floor has 3/4" pipes all the way to the tub fixture. The water pressure is acceptable as long as only one thing is on at a time. We have two clothes washers, 3 dishwashers, 3 water heaters, 3 full kitchens and 3 full baths.

The only thing that is not new is the feed from the water meter which is a 3/4" galvanized pipe that is probably 70 years old. It's about a 50-foot run from the street to the new copper 1" feed at the house. I am sure that replacing the supply line will help but it won't solve the real problem of "too much demand" for the single 3/4" water meter.

I want to boost the system so that the issue goes away. Which pump do I need and how much will it cost me?

Your situation involves a number of factors that make it difficult to answer directly. If the pipe is 70 years old, there is a very good chance that contains corrosion and sediment deposits that will reduce its capacity to carry water. 3/4" pipe usually carries only a maximum of about 20 gallons per minute when brand-new, so if your demand exceeds that amount (which it easily could if you have a triplex living arrangement that includes features like a whirlpool tub), then the answer may be in installing new, larger-diameter piping rather than installing a new pump.

You're more than welcome to review our pressure-booster pump options, but be advised that those pumps start with a minimum of a 1" suction line, and some have 1.25". It's essential that you do not starve the pump by putting a pump with a 1" suction fitting on a 3/4" feed line, for instance. A pump needs to always be served by a feed line at least as large as the inlet to the pump itself.