I will be leaving my home for three months, during winter, where I can expect the weather to go below freezing.

My question is if I should turn off the main water valve in my house or just to the sinks, toilets, etc? If I should turn of the main valve, should I also turn of the hot water heater, and if so, are there any precautions I need to take (i.e. drain the tank)?

I plan to keep the heat on while away. My last extended trip, I came home to find my toilet drain had sprung a leak and my downstairs kitchen was flooded. I would like to avoid this issue in the future. But, I have also been told to prevent freezing of pipes, I should keep the water on and slowly dripping. Not sure if it matters, but I think most of my pipes are PVC. I also have no sump pump.

  • Think of PVC pipe like a windshield, it can freeze and defrost just fine with slow heat, but if you pour hot water on a ice cold windshield it goes into shock and cracks, but since pvc is a concealed cylinder, you could leave the faucets dripping really slow so that it doesn't go into shock once you get back
    – user70085
    Oct 9, 2018 at 3:06

1 Answer 1


Wow, this got long but after 2 times replacing pipes and a toilet in a detached garage this is what I learned to do many years ago. After that we have not had problems, but we're in a warmer climate now....

If you turn the water off please turn the power off to the water heater or if gas turn it to pilot. If there will be no heat at all and your area gets below 27 to 28F it would be a good idea to drain the water heater. Turn the main water supply off, or if on a well drain the pressure tank first, then open the sinks, flush the toilets and last open the outside hose bibs or faucets. This will pull as much of the water out of the pipes possible and even if the water in the pipes freeze there won't be solid water to expand and break the pipes.

This is what I found on exterior water lines in out buildings that were not heated with -23F and a wind chill of -80+ or cold enough to toss a hot cup of coffee 5-6 feet and it hit the wall like a shlushie (don't do this with white walls because we thought it was fun did it maybe a dozen times on the detached garage the next spring I had to repaint that side of the garage from the big brown spots but it was fun).

So if unheated drain water turn power off flush toilets and you should be ok. It took me 2 years to get it right but no problems after that.

  • 1
    Probably not a bad idea to pour some RV antifreeze down the sinks and in the toilet tank to keep the water in P trap and tank from freezing.
    – Tom
    Oct 9, 2019 at 19:19

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service and acknowledge you have read our privacy policy.

Not the answer you're looking for? Browse other questions tagged or ask your own question.