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I was cleaning the shower drainage pipe (removing hair etc) in the upstairs bathroom and I can see water around 1 foot deep. See the pic.enter image description here

Is that normal? Shouldn't the pipe be empty? If water stays stagnant like that, it can't be good.

If this is a problem, how do I fix it?

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up vote 11 down vote accepted

Yes it's normal and what you want. It's called a P-trap and the water sitting in there seals out the sewer gasses.

My ASCII P-trap:

                  \ /
                  | |
   __________     | |
   _________ \    / /

The asterisks would be the water that forms the stopper.

In an empty home or in drains that are infrequently used (such as a basement) you these traps can eventually dry out from evaporation and let sewer gasses seep in.

In your case, if you aren't going to use the shower for months on end, I suppose you could add a drop of bleach to the drain. If the shower is used semi-regularly, there should be no issues at all.

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Thank you for your answer. You answered exactly what I was asking for. Before I accept, one question I have is that there are a few baths and sinks that I don't use for months together. Is it advisable to open the tap once in a while or how is the bleach going to help? – coder net Sep 19 '11 at 11:28
The bleach suggestion was in case you were worried about grime/slime sitting in there. As for baths/sinks you don't use for months at a time, it certainly wouldn't hurt to turn the tap on for a minute once a month or so. As to whether or not they'd actually dry out in that time would depend on your climate/humidity. – DA01 Sep 19 '11 at 13:35
what will happen if they dry out.. is it certain that the sewer gases will seep into the house? any problem apart from a potential smell? – coder net Sep 19 '11 at 13:47
You'd notice the smell long before any potential other issues (of which I can't really think of any...I guess I wouldn't light up a smoke in a closed bathroom full of sewer gas, I suppose) – DA01 Sep 19 '11 at 15:48

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