Do you need a pee trap with a garbage disposal?

Answer 1

Most plumbers would say yes, of course . . . but I have my doubts. The purpose of the pee trap is to prevent sewer gas leaks into the home and to catch your engagement ring when you drop it in the sink. It provides a low point to trap water and accomplishes both purposes. It seems though, that the disposal itself should accomplish both missions--it should provide a low point and sewer gas seal, and crunch that engagement ring before it gets to the sewer rats. Depending on your investment, the wrecked disposal might be more to replace than the ring. The trap itself is not a big deal to install, but it does take up room under the sink (already limited by the disposal) and it could inhibit the flow from the disposal after the small chunks exit the unit. For these reasons, I am tempted to ignore the advice of the plumber and just angle the drain pipe to provide maximal flow into the drain stand pipe. It would be easy to install a trap later if needed, and I get the basement drains roto-rooted once a year anyway due to tree roots that collect in the old tile drains from the yard that connect to the sewer. The pee trap seems pointless to me with a disposal. It takes up space, is a pain in the ass, and is very likely to inhibit flow from the disposal. Your local codes may mandate it, unless you install it yourself (blame the installation on the local plumber to save face if needed). But beware, fiber materials from your disposal (celery, bananas, peanut shells) could clog your standing drain pipe. But since these materials are soft, they should be easily snaked out if that happens. I plan to grind everything in the disposal and take my chances. Martha Stewart would disagree, but she seems unhappy to me.

Well that's my take on it. Good luck!