Why 3 dump valves?

Not really a conversation on electric dump valves. For me that conversation is ended - I will be getting them. What it’s really about is why I need 3 of them. I get that I have 2 gray talks and one black - so three valves is the norm - but why?

I have not looked under the rig, but my first inclination is to only install 2 valves - one black and one grey to empty both grey tanks.


The question for the team - what is the down side to this?

You have 2 grey tanks. Therefore you have pipes coming from each one, resulting in the need for 3 valves. I am sure you could have them plumbed to each other, but why bother?

The reason for 2 grey tanks is to balance the weight...one to the front (galley) and one to the rear (shower and sink).

Two gray tanks. If you remove the coroplast and insulation you would see the one gray is for the kitchen, then the black tank under the toilet, then the shower & bathroom sink gray water tank. I do not think you would like the capacity of one gray tank and there isn't much room under a lot of the the fifth wheels. Mine is tight in most areas.

Depending on how the grays are currently plumbed, you might have to make changes to tie them together while keeping them separate from the black contents when that valve is open.

And if you ever camp in freezing weather, water standing in pipes between tank and valve might freeze sooner.

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I think we are all on the right track. I will take a look next weekend and scale the job to see how big it is. The goal with just one gray water valve is saving the additional cost of another electric one, ( around $120.00). I picture the system, working back upstream from the end cap, as having a “Y” connector for the black tank. At the other side of the “Y” the two valves for the 2 gray tanks. I think the other question, ( and I believe it may be more of a Heartland question) - what is the design or engernering reason for two valves? I’m sure they would only use one if they could.

Of course it could be a corporate culture thing - “three tanks - three valves - take it or leave it” Surprisingly, right now that makes the most sense.


As far as weight - Not changing the dynamic, (function), of the tanks. They would get emptied every time I roll the RV.

On your Landmark, the Gray #1 tank is probably mounted low, in the drop frame area. The Gray #2 tank is probably in the higher rear section under the kitchen. When you tie them together, the water from the kitchen will pour into the Gray #1 tank.

I'll hazard a guess that you'll end up dumping your gray tanks more frequently.

And again, if you ever get into freezing weather, you'll wish the valves were located right at the tanks. If you fill the 1-1/2" pipes with water in the winter, they will be first to freeze.

Last winter there was a guy at our park whose rig had the gate valve separated from the tank by a few feet. He had to build a heated enclosure under the pipe run to thaw it out so he could dump the tank.

Opening the coroplast to change out the valves is a pretty labor intensive of job. Before you're done, $120 in materials cost will pale by comparison.

I have four valves 2 grey and 2 black. Manual valves work great why I would want electric dump valves is my big question. I monitor the draining at all times making sure no leaks occur and I know when the tank is empty by watching the flow in the clear 45* fitting. I have even added an extra manual valve at each of the drains just in case I pull the wrong drain.