Plumbing Mod to Improve Waste Tank Usage

[TallPaul]

Wife, kids and I really like this motorhome better than any other one we have owned (2000 Gulfstream 28' Class C on Chevy 454 one ton van chassis). One problem with it though, and this is apparently a high end feature, is that the bathroom sink drained into the black tank instead of the grey. This is supposed to give good hydration to flush the tank when you dump, but for us it made is so we had to dump twice every 24 hours. Also, the grey tank would only be partly filled, probably not even half. So I rerouted the bathroom sink drain to the grey tank via the kitchen sink drain. It wasn't easy though. Here is the access to the drains:



As you can see, there is a small opening and a long narrow passage to the left. The sink drain to black is just a bit left of the sink, but the kitchen sink drain is almost to the back wall on the far left.

Here is a shot of the finished work (all new work is white except the three way connector on the kitchen drain):



You can see the old sink drain to the black tank as a verticle black pipe behind the white pipe that angles down. You also should be able to see where it connects to the kitchen sink drain pipe, but there is a close up of that in the next post:

[TallPaul]

Wife, kids and I really like this motorhome better than any other one we have owned (2000 Gulfstream 28' Class C on Chevy 454 one ton van chassis). One problem with it though, and this is apparently a high end feature, is that the bathroom sink drained into the black tank instead of the grey. This is supposed to give good hydration to flush the tank when you dump, but for us it made is so we had to dump twice every 24 hours. Also, the grey tank would only be partly filled, probably not even half. So I rerouted the bathroom sink drain to the grey tank via the kitchen sink drain. It wasn't easy though. Here is the access to the drains:



As you can see, there is a small opening and a long narrow passage to the left. The sink drain to black is just a bit left of the sink, but the kitchen sink drain is almost to the back wall on the far left.

Here is a shot of the finished work (all new work is white except the three way connector on the kitchen drain):



You can see the old sink drain to the black tank as a verticle black pipe behind the white pipe that angles down. You also should be able to see where it connects to the kitchen sink drain pipe, but there is a close up of that in the next post:

[TallPaul]

Here is a closeup of the connection to the kitchen drain pipe:



The rubber three way connector sure was a lot easier to install than trying to squeeze in a hard pipe with that strong smelling PVC adhesive.

[Ray,IN]

You're right. Several RV manufacturer's did this to solve the problem of plugged black tank complaints. Most folks don't use adequate water when flushing, often a "pyrimad" is the result. Looks like a neat job.

[TallPaul]

Good point Ray. We drink a lot of water, so black tank hydration is no problem. I can see where a pyramad ciould happen, but depends on tank design. My last motorhome, an Itasca Sunrise 32 foot had the toilet enter the black tank at its far end and the toilet pipe curved. The curve plugged several times on our first trip (2 weeks). Very frustrating. Curve was because toilet was centered outside the tank location.

My current motorhome toilet dumps pretty close to the well where the drain is, so not likely to get a pyramid.

I had a '90 Damon Escaper C 27' for 5 years and never had a problem with the black tank or toilet plugging.

As I said at the beginning, I really like this Gulfstream. all the tanks are very well desiged with wells and sloping. All the fresh piping, pump, heater bypass, drains, etc are in one compartment in the basement. Black and grey in another basement compartment and, the nice part, the sewer hose hookup is through the floor of the compartment so I don't have to route itto the compartment like the Itasca did.

Yeah, there could be improvements, and I am making a lot of them, but all in all, the Gulfstream I have ia a very nicely constructed and logically laid out motorhome, including the L shaped kitchenette, which gives more counter space.