We're looking at the Grand Design Momentum 328m which has two separate 52 gallon grey tanks, one for the shower and another for the sink. It has 160 gal of fresh water. We're likely to use much more water for showering than at the kitchen sink.It also has a 78 gal black tank.Is there a way to connect the two grey water tanks together so that we can utilize some of the kitchen sink tank for the shower?

Can't imagine filling a black tank with a capacity of 78 gallons....(That's a lot of flushes and a lot of $*1t).Better to run one of the gray tanks into the black tank....This will also help it dump and clean better with the extra water.

downtheroad wrote:Can't imagine filling a black tank with a capacity of 78 gallons....(That's a lot of flushes and a lot of $*1t).Better to run one of the gray tanks into the black tank....This will also help it dump and clean better with the extra water.Yes, I figured we could part of one of the grey tanks into the black. I'm wondering if there's a way for one grey tank to share with the other grey.

Sure, we did it by making up a 3" pvc pipe with rubber elbow and 't' at opposite end with vallterra twist connectors on our 2 tank rig that had separate dumps. Simply put a valve on the end of the connector, open the dumpvalves, so that levels equalize. On the next rig that had 2grays with one dump, we just made up a twist on valve to put on the dump, then open the 2 gray, even the black to let all the tanks equalize. Use all your waste capacity.

You can use a twist on valve at the main drain exit, if both gray tanks empty from there. You can just open both tank valves then to make one big gray tank.Jerry

Here's an image I got off rvtrader that shows the dump valves. While the dealer states that there are two grey tanks, this photo seems to indicate a single grey tank valve.

connecting grey tanks to get more capacity for the shower

SDcampowneroper
Explorer
Nov 17, 2017
Sure, we did it by making up a 3" pvc pipe with rubber elbow and 't' at opposite end with vallterra twist connectors on our 2 tank rig that had separate dumps. Simply put a valve on the end of the connector, open the dumpvalves, so that levels equalize.
On the next rig that had 2grays with one dump, we just made up a twist on valve to put on the dump, then open the 2 gray, even the black to let all the tanks equalize. Use all your waste capacity.
Lexx
Explorer
Nov 17, 2017
downtheroad wrote:
Can't imagine filling a black tank with a capacity of 78 gallons....(That's a lot of flushes and a lot of $*1t).

Better to run one of the gray tanks into the black tank....This will also help it dump and clean better with the extra water.

Yes, I figured we could part of one of the grey tanks into the black.

I'm wondering if there's a way for one grey tank to share with the other grey.
downtheroad
Explorer
Nov 16, 2017
Can't imagine filling a black tank with a capacity of 78 gallons....(That's a lot of flushes and a lot of $*1t).

Better to run one of the gray tanks into the black tank....This will also help it dump and clean better with the extra water.

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connecting grey tanks to get more capacity for the shower

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