Gray tank/sink stinch

[Rn5west]

Hello all,
We are totally stumped about our gray tanks draining slow and kitchen sink and bathroom sink smelling awful whenever we run water. We take great care of our tanks and have also replaced the air admittance valves under both sinks. We have used chemicals and Cascade in an effort to eliminate the odor. We make sure no large food particals go down the drain and have a mushroom in the shower to catch hair. We know there are two vents on the roof but are hesitant to mess with one because we don’t want to remove the roof sealant unless it’s necessary. We purchased our 2020 Northpoint 310 RLTS in January but had a travel trailer before that without any issues.
Thank you in advance fir your time 😊

[Marine71-76]

Is the smell coming from the faucet when the water is turned on? If so, it could be coming from your hot water heater. After we have been camping & once the unit is back in storage, we have drain the hot water tank. Never had to do that would our previous unit.

DW was reading the brochure looking for something else and found where it is recommended to put baking soda down the sink drains to control smells in the holding tank.

[Rn5west]

We did consider that but never smell it from the shower. But to be safe will flush our hot water tank. Thank you so much for the reply . I will update with my findings.

[RVermont]

Try using a bucket of water or a hose from out side and pour that down the sink at about the same rate as your faucet delivers. Does that cause the odor? You need to start to to eliminate and split the issue apart. Ie is it you water supply or your drain waste piping. How many grey tanks do you have? Do you have a washer dryer hook up that you don’t use? The trap might be dry. Some shower drain are flapper traps and if the odor is from the the drain waste system the flapper trap will prevent odors differently than a traditional p trap.

You mentioned slow draining grey tanks do you mean when you are dumping them? Or slowing draining sink into grey tank.?