Bad smells, Stinky bathroom sink

[BB clamper]

Hi ya’ll, I recently bought a 2022 Thor Windsport in almost new condition. Like every new coach, I’ve been working the bugs out of it I’ve been using it often for work and recently I noticed an awful smell coming from just the bathroom sink but only after I turn on the faucet. I mean it’s so bad I have to back out of the bathroom to brush my teeth! It smells as if it’s piped into the black tank that hasn’t been emptied. The trap under the sink is supposed to keep nasty smells and gases out but this one seems to be letting the smells out past the trap. I use the campgrounds facilities as much as possible and always drop in a deodorizer packet. The toilet never has a bad odor . Even after I empty and flush the tanks it still reeks! Any ideas?
Thanks

 

[Joe Hogan]

What To Do If Your RV Water Smells Like Rotten Eggs

If your RV water smells like rotten eggs, here's a troubleshooting guide to determine what's causing the problem and how to fix it.

www.doityourselfrv.com

 

[Rich W.]

Water evaporates out of P traps in hot weather so you have to make sure they are full. Also try to keep any and all organic stuff from going down the drain and flush the gray tank thoroughly. Adding something to keep it clean will help too. There is another recent thread here on the subject that deals with this in more depth.

 

[Texas Clodhopper]

I took Neal's advice on cleaning the tanks and this eliminated the odor and my tank gauges work again. Add Liquid Dishwasher detergent to your half-full tanks and then drive for a day. You may be shocked to see the gunk that flows from your tank when you empty them.

 

[Wemustrv]

I would also recommend checking the suter valves. Our coach has 3 one under kitchen sink one under the bathroom sink. There is also a vent for the toilet(located on the roof) These are also know to go bad. Changing out suter valves took care of our odor issue. Valves are cheap and I keep extra couple in the coach.
Amazon product ASIN B000KKSP52

 

[LMHS]

AVV = Air Admittance Valve

Also called "Studor" valve (a brand name of an AVVs), "Cheador" or "Chedor" valve (former brand name of an AVV and I don't remember the exact spelling) and "Cheater" valve (a corruption of "Cheador" OR a reference to how the valve can be used to "cheat" and not install a vent stack to allow drains to drain quickly).