Shutting A House Down: Will Water in Traps break pipes?

Simple question: when you drain the water from the pipes (in a house which will not be heated in winter), do you need to drain the traps? As we all know, water expands upon freezing-and if confined in a pipe, the expansion will rupture the pipe. In a trap, the water is free to expand-so, will the ice fracture the pipe in a trap?

I’m pretty sure you should endeavor to keep the traps filled, as the water barrier prevents noxious sewer gases from invading your abode. Once the lines are drained, there’s plenty of space for the water in the traps to expand.

Very unlikely. Freezing is usually a problem in the pressurized supply lines. Drain pipes have lots of space for expansion.

Your biggest problem will probably be evaporation – if the trap empties out, the house might get a bit whiffy.

Most of the hunting camps that I know of pour some anti-freeze in the drain traps after draining the pressurized lines. They use the same type of anti-freeze as that used for RVs.

I’m pretty sure it’s this product, or one similar to it. Easy inexpensive protection.

When I was a kid, one year when we retreated from our summer cabin, we did the anitfreeze in the traps and drain the waterlines bit, only forgot about the water trapped between the shower valves and shower head, about two feet worth. They broke.

There is antifreeze for drains and water systems for winterizing.

I definitely recommend antifreeze. I left an apartment unoccupied for months, the water in the traps evaporated, sewer gases filled the bathroom and all the walls were moldy and stinky in the worst possible way. The bathroom itself had become part of the sewer. I recommend antifreeze and, if left fro a long time, some oil over the water in order to prevent evaporation.