Winter and P-Traps etc

[OlJarhead]

I've been thinking about this a while and wondered what your input would be:

If you install P-Traps under the floor (for tubs and showers) in a Post and Pier type foundation like mine, how do you keep them from freezing solid?

I've thought that I would probably have to insulate the foundation with foam board but even that probably won't do much good when it's well below freezing right?

In that space is roughly 1000 cubic feet that would need to be kept at least close to freezing or slightly above it...then with insulation on all pipes perhaps it would work...but when you leave and it hits -30 the P-Traps will freeze solid (and perhaps crack)......so what to do?

I might add that I put heat tape/trace on my sewage pipe now as it is and then cover that with extra insulation and hook it up to my solar power during the winter so that it remains warm enough not to freeze but it would take too much energy to do that with all drain pipes (2 sinks and a tub/shower)....

So what to do?

[MountainDon]

If the drains go to a septic or sewer system you need the traps to block the sewer gasses. So most will use RV antifreeze.

My kitchen sink is fitted with a hard to find P-trap that has a 3/4" threaded drain cap. I've been removing the cap and catching the drain water in a can and tossing it out the door when we leave. Peternap had the idea of using a sprinkler system solenoid valve. In the end I think he set up the sink with no trap as it just drains outside in a hole or something. Our kitchen sink does that.

POur shower has no P-trap either. It drains into a rock filled barrel in the ground.

[OlJarhead]

If the drains go to a septic or sewer system you need the traps to block the sewer gasses. So most will use RV antifreeze.

My kitchen sink is fitted with a hard to find P-trap that has a 3/4" threaded drain cap. I've been removing the cap and catching the drain water in a can and tossing it out the door when we leave. Peternap had the idea of using a sprinkler system solenoid valve. In the end I think he set up the sink with no trap as it just drains outside in a hole or something. Our kitchen sink does that.

POur shower has no P-trap either. It drains into a rock filled barrel in the ground.

Interesting idea with the 3/4" plug -- I like it.

Our system will drain into a gray water settling tank (55 gallon drum) and then into a dry sump to leach into the ground...but it sounds like I might want to include some way to drain the traps easily.  Thanks for the idea.