Loss of cold water


Old 01-01-03, 09:23 AM
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Question Loss of cold water

Just recently moved into 25 year old house. When taking a shower, if someone flushes any toilet in the house you have an immediate loss of the majority of the cold water supply in the shower. I've seen this on TV comedies, but never experienced it myself. I've lowered the temperature of the hot water heater (it was set pretty high) and that has had some impact. Any ideas of the cause or to the solution or are we destined to do the hot water dance?
Old 01-02-03, 01:57 AM
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Although, I'm sure you could repipe and cut down on the problem immensely and perhaps that is what you'd like to do; But, I learned at a very young age not to flush when someone is in the shower for the very reason, you cite and though I'm sure that I've probably lived in a house or two where it probably wasn't an issue; I learned around two years old not to flush and it's just something that I don't do out of courtesy.

Off the top of my head; You could increase the size of the waterline which feeds the house and that would have some effect; Larger cold water pipes under the house as a whole would be beneficial, or you might be able to remap the system that serves the shower to where it comes before the toilets. I'm not sure exactly which "answer" or combination of "answers" would serve you best and now, I'm kinda wondering myself because I'll be replumbing my whole house starting in about three weeks.

But, the easiest and least expensive thing to do would be to refrain from flushing when someone is in the shower...

Last edited by magister; 01-02-03 at 07:26 AM.
Old 01-02-03, 09:31 AM
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If this is an old style shower valve, 2 or 3 handle type, replace it with a pressure balance type of valve, a scold guard valve, will help the problem your having.
Old 01-02-03, 04:02 PM
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Plumber2000 is right, a pressure balance shower valve will atleast kill the symptom of getting burned when the cold water is robbed by another fixture in use while you are in the shower... Of course, the ROOT of the problem lies in the fact that you don't have sufficient volume to the fixtures to begin with... Do you have galvanized pipes in the house? If so, it may be time to start considering replacement with copper or cpvc soon... If you have only copper, then check the meter first and make sure your water is turned all the way on (silly but I have seen many meters about halfway on)... Also if you have copper, 25 years ago, they were still using "globe" valves that were very restrictive and in fact are not code anymore... they can be replaced with gate valves which can significantly increase volume also...
Old 01-02-03, 07:06 PM
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Thanks to all that posted replies. We were figuring that it was a problem of insufficient water supply. So we sat back and thought: all the cold water is just rushing to fill up the toilet tank so if we limited the amount flowing to the tank... I checked and all the toilet valves were fully opened, so I shut the valves to a point that the toilets fill at a slower, but acceptable, rate. (Who needs the toilet filling for 15 minutes?!). And guess what - our problem is solved! For FREE!! No replumbing the house, no digging up the yard for a larger water supply line and definitely no waste in the bowl sitting & waiting to be flushed!!

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