Yogurt, yeast?
baking soda or if there is a disposal lemon or orange rinds.
2. Did you check to see if you have a venting problem?
Chlorine bleach will eliminate bacteria that causes plumbing odors, a dousing twice a week will help. Also, regularly use foaming drain cleaner to eliminate organic materials from inside the pipes that foster bacteria.
IIRC, Roto Rooter makes some kind of enzyme treatment that comes in a gallon bottle and is supposed to help clear out fats/proteins and things like that. Typically, it is supposed to be used once a month to keep the entire water line system clear, but it can be used in a pinch as a “soft” drain cleanser. We had a stopped up sink a few weeks ago that I used it on because I didn’t have any of the “good stuff” on hand, let it sit overnight, and cleared the sink line right out and it’s been flowing well to this day. It should work if your odour/grime problem is organic (i.e. fats and grease, food, etc.) but won’t work if its scale/deposit/corrosion or something else inorganic.
Have you checked the vent to make sure it isn’t plugged? Also, make sure you have “p” traps on all the drains. If not that can allow sewer gases into the house.
I use baking soda and vinagar. Put the soda down the drain, first....then pour on the vinegar. It bubbles all of the ‘ick’ away. When I don’t use that....I just use bleach.
You didn’t say anything about the P-trap that should be below the sink. Is there one there?
Throwing out ideas here...
1: Because your drains are not ordinary gravity feed items, an ordinary gravity feed plumber may not be able to correctly diagnose & cure, LOL.
2: I am not so sure a chem treatment mild enough to fix this would have any lasting effect since you’d be washing it away every time you used either sink, no?
3: I would confirm that your venting is adequate and not plugged up with a bird’s nest or something silly like that. You might need a dual vent, one either side of the offending fixture.
4: It may be that you need to install another trap along the shared drain line, if I am reading your prose description right.
5: It is possible that the pump is either pumping your line dry enough so that the trap doesn’t stop vapors *or* it’s pumping so dry that the trap(s) do not work right. That second thought doesn’t seem possible, but I’ve seen (and smelled) weird problems before with drain pumps.
6: Got a fan in the bathroom?
...this time of year mnake sure the vents on the roof are not clugged (leaves,nest, bears, north jersey...*grins*)
I think you have a Democrat stuck in your pipes........
BTW, I like vanities.
The pump may have a one way air valve, to prevent it from forming a vacuum, which may have malfunctioned. One thing to check.
There should be no need to pour anything down the drain, as long as there are traps. Do both sinks have a trap?
An s-trap will leave water at the bottom of the trap to prevent back flow of gases. Don't treat the symptom (odor)...cure the problem.
One of the reasons that a sink will produce noxious fumes occassionaly, is that due to seldom being used, the water in the trap evaporates, and the trap under the sink fails to work as it’s supposed to. Then, the unpleasant odors come up through the trap and the whole place smells like a ceptic tank.
Now, assuming that the sinks both run down the 1.5 inch drain pipe without obstruction, there are two ways to fix this problem. If you have an obstruction, you can either use an enzyme to fix the gunk build up - or do it my way. Buy a container of Rid-X; fill the sinks with warm water, and empty the box of Rid-X in the sink and let it sit overnight. The Rid-X is dried bacteria that keep your ceptic tank working right. Well, the stuff that grows inside your pipe is ‘food’ for the bacteria, so my first plan of attack is to establish a bacterial colony along the pipes to perpeturally keep the gunk under control. Hence the Rid-X. Let the bacteria get going well in the sink, overnight soaking should be sufficient. Opent he drains and let it drain. Bear in mind, bleach and other noxious chemicals kill your bacteria, so don’t use bleach for a week or two. Let your bacteria colony get established. Once established, you can cut the numbers down - but it will be difficult to wipe it out entirely. This is good.
Now for the 2 methods to prevent the sink stink
1. Every week, run a gallon of water into each sink, that will fill the trap with water.
2. If you just don’t use the sink frequently, dump a couple tablespoons of MINERAL OIL into each sink. The Mineral Oil will float above the water, and Mineral Oil does not rot, nor does it evaporate. Assuming you seldom use much water, or pour water down the sink infrequently, this will make and keep a vapor barrier for a long time, with just a little water that you do pour down the trap flowing through the mineral oil barrier, and filling the trap again. If you fill the sink up and drain it, you will flush the mineral oil down the tubes and need to re-treat it. It’s cheap, it’s easy and it only takes a little bit, just enough to make a film of oil between the trap and the open air.
I have used chlorine powder for swimming pools. It has a higher consentration of chlorine than regular bleach. I used it to sanitize my well head because the water smelled bad.
Are there “P” traps in the lines? If not, gas is free to enter the building.