Sizing a home system to improve low water pressure
August 24, 2010

We received this inquiry the other day:

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?

It's a good question, and since our home water pressure booster pumps are such a popular item, it's worth examining and sharing our comments with you. Here's our reply:

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.

If you have questions about pumps, water service, or anything else in our field of service, contact us and we'll be happy to help.

August 2010
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last revised August 2010