That valve by the sink in the bathroom . . .

Question

Got stopped at a campground a few days ago, and was assaulted by a really terrible smell in the bathroom. Cut to the chase: I found it was that valve that allows air to flow when the sink is drained. (Thanks to others on this site who made me aware of that valve.) So I put electrical tape over the openings, as there were no hardware stores in the area. It has been a few days and a couple hundred miles since then, and absolutely no smell.

My question: is there any compelling reason why I should replace this valve? Our inclination to fill that sink with water just isn't there; we use it to brush teeth and wash hands under running water and not much else. Am I missing something here?

you_can_t_take_ · Answer

If you use the drain plug and then try to drain the basin you will have a sink that has to 'burp' to drain properly since the purpose of the valve is to let air into the drain line and to prevent the drain from syphoning out which will give you back the smell through the sink drain.  It's best to replace it.. they are pretty cheap.

bguy · Answer

When you dump your holding tank the vacuum will/can empty out your traps. You already know what it smells like....
You should find one by the kitchen drain and if you look hard enough there's one for the tub/shower. You should be able to buy one for around $2.

ron3rd · Answer

Replace the valve, you need to vent the drain for proper drainage.  They're cheap at home centers; called an "air admitance valve" or "cheater vent".  Under 10 bucks. Simple to do.

old-biscuit · Answer

Air Admittance Valve......Simple rubber flapper that allows air into drain line to prevent 'P' trap from getting sucked dry when you drain your grey tank.No water in 'p' trap and you will constantly smell grey tank odors.Now you can unscrew it, go to most any hardware store and get a new oneORLeave it taped off and then after dumping tanks run enough water into sink to put water back into 'P' trap.....each and every time$10 or your time/effort every time you dump

slarsen · Answer

OK, I'm convinced. I'll get a new one. Thanks for your advice.

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That valve by the sink in the bathroom . . .

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