Water valve under sink

[Ruthless]

There’s a valve in the waterline under the sink that broke in our SMB, and we now can’t fill the water tank using a hose from the outside port. Is this valve really necessary (I was never certain about its function). Should we replace the valve or can we replace it with some PEX pipe.
Thanks for any insights.

[N147JK]

To clarify, the valve is in line between the fill port on the outside of the van and the water tank. Is that right? Nothing actually to do with the sink? Can you post a picture?

[86Scotty]

Agreed, pic needed. If it's a one way valve (check valve) which keeps water from coming out of the fill port from the fresh water tank then you need it. And if so they are cheap and common in RV world.

[Ruthless]

It’s a quarter turn valve. When it’s in its current position, the water from the outside port goes directly to the drainage port ( see photo). When it’s in the other position the water will fill the tank. I didn’t even know this valve under the sink existed until the drainage valve started leaking and somebody on the forum said I could turn this other valve under the sink and that should prevent it from leaking (I wasn’t able to find the thread). Since then, I fixed the drainage valve so I’m thinking maybe this other valve isn’t necessary ( it’s very difficult to get at it). (I can’t get the photos orientated correctly. The valve is behind the sink drain. The other is the drain valve near the propane tank).

[Twoxentrix]

Don't know if this helps, I downloaded it from another Thread a while back (But if you have the Sportsmobile Manuals you should be able to find something similar & specific to your van):

[N147JK]

Could it have something to do with switching between drawing from the tank verses using water from the "city" connection? One way cuts off drawing from the tank (use city water) the other way cuts off city water (use tank water). Drain valve should be closed.. this valve is for draining the tank - no other purpose. Just my best guesses..

[Ruthless]

I couldn’t find this valve illustrated in any of the diagrams in our SMB manual. I guess the best thing to do is replace the valve as it must have some yet to be determined function.

[Ben10281]

Could the valve be a way to blow out the lines from the inlet port to the drainage port for winterization? If the valve is turned so that it is connected to the drainage port, and you hooked up an air compressor to the inlet port, then you would be blowing air through all the lines, but not into the tank.

[eddyturn]

Hey Ruth. If the valve is on the floor, it is used to close off the line to the outside/fill especially in cold/freeing weather. It allows you to open the master drain to keep all that outside hardware from freezing but won't allow your inside water to flow back out. You need to have it open to fill and during the summer months, we just leave ours in the open position. I think that is what you are looking at and it's not on any drawings in our book either. You can do without it but come winter camping time, you will want to have something there.

[Twoxentrix]

Originally Posted by eddyturn

Hey Ruth. If the valve is on the floor, it is used to close off the line to the outside/fill especially in cold/freeing weather. It allows you to open the master drain to keep all that outside hardware from freezing but won't allow your inside water to flow back out. You need to have it open to fill and during the summer months, we just leave ours in the open position. I think that is what you are looking at and it's not on any drawings in our book either. You can do without it but come winter camping time, you will want to have something there.

I think you are correct.