I have a shower stall in my basement guest unit. As it's only used occasionally, sometimes the P-trap dries out. Other than remembering to add water periodically, if I haven't had any guests or I anticipate a long period without use, can I fill it with oil or antifreeze? What are my options?
Is there something I can do to avoid having the trap dry out during intermittent use? Or is there an alternative type of trap I can install during an upcoming renovation?
I'm also considering removing my wash basin (it gets moldy and takes up a ton of room) and adding a stand pipe to catch my AC condensate, but I am worried I'll experience similar issues.
Best Answer
There's two solutions to this - a trap primer and baby oil.
A trap primer is a device that has a tube running from a fixture to a seldom-used drain. Whenever that fixture is run, a small amount of water is diverted to the trap to fill it. There are also standalone primers that run based on a timer and don't rely on a fixture.
Since oil floats on water, baby oil will coat the water in the trap and keep it from evaporating. Next time you notice the trap is low, top it up and add some baby oil.
Adding a trap primer will probably be disruptive and expensive - I'd go with the baby oil.
You can use any oil, but baby oil (or plain, unscented mineral oil) won't go rancid as a food oil (vegetable oil, canola oil, etc) eventually will. Plain unscented mineral oil is sold as a laxative in most pharmacies and some supermarkets.