U-Bend/P-Trap,Where tput it.

[chiangrai]

I just had a little Toilet/brick shit house put on the side of my house today.

As soon as the concrete floor was poured I remembered that in Thailand

you must allways tell the builder to put a U-bend/P-Trap in every outlet pipe

or your bathroom will smell after a short time.

There is a U-bend built into the toilet but the drain for when you wash the floor has none.My builder says it won't smell because it's not conected to the shit pipe,it just goes straight out into the woods.

So my first question is "is this true" or do I need a U-bend.

My second question is,if I do need one where should I put it.There are 2 choices,I can dig up the earth just outside the bathroom and put a U-bend about 2.foot from the drain hole.If I do this it's more awkward than the second option.

The second option is to wait and see if it smells and if it does I can put one in but by that time I will only be able to put it about 12 feet from the drain hole.This involves much less diging because of the lay of the land,to keep a long story short.

So is it going to smell and would a U-bend 12 foot from the drain hole be less efective than one about 2 foot away.

Thanks in advance as I need to decide before they put donw more concrete..

[eyecatcher]

If there is a trap in the wc then problem solved shouldnt get smells.

With the wash down drain its better to have one because if it goes to the woods who knows how many snakes and frogs want to come to visit.

At the least i would put a mesh cover over the end.

Ideally you could do with a shower drain outlet then at least if she accidentally washes that diamond ring down you can rescue it before the snake takes it.

[bankruatsteve]

U-traps should be everywhere there is a drain. Toilets have by design. Sinks will have with the 'kit' but you have to have it and make sure the Thai installer knows how to hook it up. Shower drains will never have it unless you specify - and then you may get the smile and "what?". A vent pipe like up to the attic is another anomaly for most builders.

[chiangrai]

O.k.,thanks,

So it's best to put one in every outlet but do I have to

put it as close to the drain hole as possable or will it work just as well 12 foot

down the line.

Please say yes.

[RichCor]

Toilet (black-water) should be on its own septic line.

Sink and Shower (gray-water), on a separate line from the toilet, shouldn't have the fumes/odors of a septic line.

But a sink can have a water-trap placed just below the sink.

Shower can have a trap installed in the drain of the floor.

[canopy]

do I have to put it as close to the drain hole as possible or will it work just as well 12 foot down the line.

International codes typically require the trap to be positioned directly below the drain with no horizontal offset allowed. Some amount of vertical drop is allowed. I've seen one code for the Philippines that allows a horizontal offset of 30" maximum. It's the only spec with any leniency I have come across for that. I am not sure all the reasons for wanting it directly below the drain, but that's usually where it has to be.

[Sophon]

If you think about it, it's actually quite logical.

Over time dirt and grease will start building up on the inside of the waste pipe, and when that breaks down it will release smelly gasses. Because the p-trap is filled with water it will act as a stopper and prevent the gasses from entering your bathroom. The further from the drain the p-trap is located, to longer a length of pipe you will have where there is nothing to stop the smells from going back to your bathroom. If you have your p-trap "12 foot down the line", then you will have 12 feet of pipe where grease etc. can build up and break down, and the only place the gasses from that process can escape is through your shower drain. Whether the amount of smelly gasses are enough to be a problem is not easy to say, and it obviously won't be to the level it would be if we were talking about gasses from your septic tank system (unless you are leading your grey water to the septic tank, which would be a design flaw). But the only way to completely eliminate smells is to have the p-trap directly after your drain.

I don't have good experiences with the the inbuilt traps in shower drains mentioned by RichCor in post 5. They don't hold much water and will quickly dry out, which will break the water seal keeping the smells out. They also severely restricts the flow of water leading to flooding in the shower area, so you will often have to take the top part off when showering in order for the water to drain properly.

Sophon

Edited August 1, 2015 by Sophon