connecting grey tanks to get more capacity for the shower

I wouldn't want black contents in my gray tanks either. The lines for gray are usually smaller, 1-1/2" or 2" versus 3", and not designed to handle the solids and paper. But in practice, that isn't likely to happen unless you do so on purpose. Depends on how you use the tanks, and how they are plumbed in a particular unit, but if you give it some thought it won't be an issue. Just keep in mind that contents are not going to be sloshing back and forth between tanks. They are going to find a common level, the flow is slow, and that's about it really.

lakeside013104 wrote:

Butch50 wrote:
I have 2 grey tanks on my Grand Design Reflection and I put one of the end of the 3" dump line.

Valetrra

This allows me to keep this valve closed and open both grey tank valves to tie them together.

When I dump my tanks close both grey tank valves and hook the stinky slinky to the outlet then open the Valterra valve and then the black and let the black drain and then you have both grey's to empty to rinse the slinky.

The above mentioned system works great. I have the same set up.

I would NOT share black tank waste with grey tanks for any reason.
If you are concerned about too much black tank usage, do your business in the public CG facilities or if dry camping, use the woods. Let wife and kids use 5er facility. Just a thought.

Lakeside

I don't know about "for any reason," but I think diverting black water into grey tanks is not advisable for odor control around sinks and kitchens. As for us, our galley tank tends to fill first, then grey and black last. We do try to use the parks' facilities for, ahem, solid waste to lower volume and simplify waste handling.

Ditto for using the Valterra valve at the common curbside drain outlet to equalize tanks as needed and avoid that "surprise" when you remove the cap if any of the individual tank drains have leaked through.

Butch50 wrote:
I have 2 grey tanks on my Grand Design Reflection and I put one of the end of the 3" dump line.

Valetrra

This allows me to keep this valve closed and open both grey tank valves to tie them together.

When I dump my tanks close both grey tank valves and hook the stinky slinky to the outlet then open the Valterra valve and then the black and let the black drain and then you have both grey's to empty to rinse the slinky.

The above mentioned system works great. I have the same set up.

I would NOT share black tank waste with grey tanks for any reason.
If you are concerned about too much black tank usage, do your business in the public CG facilities or if dry camping, use the woods. Let wife and kids use 5er facility. Just a thought.

Lakeside

Not a great photo of the valve, too close, but notice the phillips head screw that I added behind the bayonet connector. This keeps it from falling off on the road, or too easily walking away with someone. Some guys probably just glue them on.

Like this valve: http://www.campingworld.com/shopping/item/twist-on-valve/27868. It fastens on to a common outlet connection for the grey tanks. CLOSE the twist on valve. OPEN the grey tank valves. Grey tank fluid seeks a common level and fluid flows from the fuller grey tank to the emptier one (if both tanks are at the same elevation).

When you dump with this in operation, connect to the twist on valve.

Page 1 Butch50 use clicky

Jerry

Can someone post up a photo of what they mean by having a twist-on valve on the outlet? I'm not picturing how this outlet allows you to share between the two grey tanks. Thanks.

I agree with those who suggested the twist-on valve on the outlet. As long as you have one common outlet for all the tanks, this is simple and so convenient. I can share between tanks, any tanks I choose, I can use gray water to back flush my black tank at dump time, and that extra valve between blissful dumps and catastrophic dumps, is a nice peace of mind. They should be standard equipment in my opinion.

A cheap way to accomplish the same thing is to put a valve on the sewer pipe outlet. When the shower tank gets high close the outlet valve and open both gray tank valves. They should balance out giving you more shower capacity. They you can close the gray tank valves.
We do this when necessary and it works out well.
Of course, another way is to chose a site with sewers...

Guess I should have read the previous posts for the same idea. Great minds....

If you ever get in a bind for gray tank space and the black still has a lot of room, you can drain the gray tank into a bucket and pour it down the toilet. Not convenient, but also serves the purpose of providing a forceful rinse-out to any solids accumulating at the toilet outlet.