View Full Version : 2021 290BHS - waste tanks

09-22-2021, 06:51 AM
Duz anyone know....if ANY grey water is routed into the black tank or just the potty?

My salesman did not know...in the past, especially in split bathrooms (shower in 1, potty and sink an another) it was common for the sink to hit the black tank to raise the water to solid ratio...for dumping ease.

Does keystone do that or is it considered passe since there is now the floor douser, er I mean black washdown sprayer? Is there a plumbing map somewhere online?

09-22-2021, 07:19 AM
Some are plumbed with gray water going into the black tank, some aren't. It really depends on the model and the day it was built. I've seen trailers with identical floorplans where one has no gray water plumbed to the black tank and another that has gray water plumbed to the tank. Identical trailers, different plumbing.

About the only way I "know for sure" that you can determine how yours is plumbed is to actually put gray water from each source "through the system" and then open tank valves to see where the waste water drains.

I'd start with the bathroom sink, run it about 10 minutes (25-30 gallons) then go out and open waste tanks until you get a discharge. Annotate which tank had water as the "sink tank". Then do the same with the shower. Label that tank "shower tank" (they likely are the same tank). Next do the galley sink and label it as well. That should leave only the black tanks, and if you have 2 toilets, a second sink. Verify where that second sink drains using the same process. Likely it will drain into the black tank for the adjacent toilet.

Essesntially, it's just "an exercise in exclusion" with appropriate markings during the process.