Variable water pressure in my home...

April 12, 2007 12:33 PM

Why is the water pressure in my house so variable?

I have not made an exhaustive investigation, but it seems like sometimes the water pressure in my kitchen sink and master shower varies without being related to anything else in the house being on. The only thing I can think of is that when the water heater is filling it is diverting water from everywhere else. Is there any way for me to figure out what is happening before I call the plumber?

posted by mzurer to home & garden (6 comments total)

Keep a brief record of when it's low and high. Neighborhood demand can do it. Is it low in the morning and at dinner time? That could be it. If it's low in the middle of the night, you can rule that out. Also find out when the main pressure reducing valve was replaced.
posted by weapons-grade pandemonium at 12:44 PM on April 12, 2007

If the feed pipe to your neighborhood is near capacity, then during times of great demand the pressure can drop. (We usually use water as a way of explaining electricity, but in this case I'm going to do the opposite: water pressure is like voltage, and when there's a lot of demand, reaching the limit of what the pipe can provide, then pressure drops.)
posted by Steven C. Den Beste at 12:50 PM on April 12, 2007

Assuming you have the usual sort of american water heater, your water heater is never "filling" in daily use. It is full. Turning on the hot water causes more water to come into the water heater at the same rate water is leaving.

Get a water pressure gauge, and attach it to one of your hose bibs. See if you are having a pressure drop there at the times you notice the lower pressure in the house.
posted by yohko at 1:38 PM on April 12, 2007

This happens a lot in suburban California neighborhoods early in the morning- usually because everyone has their irrigation set to go off at the same time. I know it made a particular client's early morning shower quite hellish.
posted by oneirodynia at 2:49 PM on April 12, 2007

Are you on a well or city water?
posted by Raybun at 4:45 PM on April 12, 2007

Good ideas all - I am in Los Angeles on municipal water...
posted by mzurer at 10:42 PM on April 12, 2007