Fresh water tank drained with Grey water dump.

[Missionman]

We just got back from our first outing with our new to us 1992 HR Aluma Lite 31ft MH and had a great time. Before we pulled out of our spot I filled the freshwater tank about 1/4 full so we would have water for the trip home. I dumped the Black water just fine but when I dumped the Grey water at the campgound it also drained the freshwater tank. Did I miss something? is there a valve that is open and should not be that I need to find?
Thank you for any help you might be able to offer.

[COMer]

Yes, there would definately be a drain for the fresh tank but normally it drains directly out of the tank, and onto the ground.  Not through your sewer connections.  I would certainly find the drain to see if it is open and to know where it is for future use.  There might even be a sticker on the side of your rig near where bit is that tells you of it's presence.

[RV Roamer]

It would be most unusual for the fresh tank drain to go through the gray outlet, but anything is possible.  Nor can I think of any normal valve arrangement that would do that sort of thing.

I'm curious - how did you determine it was that emptying the gray tank did this? If there was an open connection between fresh and gray, the water should have poured into the gray tank as you were filling the fresh. The water would have left the fresh tank whether you emptied the gray or not.

I think we have some other owners of older HR coaches here, so maybe somebody will have some ideas.

[Jeff]

We have pumped our fresh water into our grey while driving by leaving a shower faucet turned on.

[John From Detroit]

What Jeff Said (Though to date I've not done that yet)

There should NEVER be any connection (Direct connection) between the fresh water and the waste water.. NO connection at all.  if the fresh tank can drain via the sewer lines and valves then you are drinking waste water and that... I'm sure you are not.

Thus it's got wo be what Jeff said.. you had a faucet open and pumped it over.

Either that. or... you left the fresh water drain open and simply did not notice that it had all run out till you dumped.

[tvman44]

I would think that would be illegal, surely unsafe.

[Carl L]

It would be most unusual for the fresh tank drain to go through the gray outlet, but anything is possible.  Nor can I think of any normal valve arrangement that would do that sort of thing.

Boy howdy it would be unusual!  In fact, a cross connection between the drinking water system and any waste water system is a major problem.   That is why there are vacuum breakers on dish washers and lawn sprinklers --- to prevent siphoning of waste water back into the potable water system.

I would really want to know what is going on here if that were my rig.

[Missionman]

I found the problem, the fresh water drain valve under the bed was left open by the previous owner and apparently it drains through the grey water dump.
Thank you all for your input and help.

Michael

[ArdraF]

I love easy solutions!  Thanks for reporting back.

ArdraF

[Missionman]

We were out with the MH over the weekend and I had a chance to explore further, the fresh water drain does not go into the grey water tank but drains on the other side of the MH onto the ground.

[aka Porky]

We were out with the MH over the weekend and I had a chance to explore further, the fresh water drain does not go into the grey water tank but drains on the other side of the MH onto the ground.

That makes a whole lot more sense.  Even the best back flow valve could not be trusted to prevent possible mixing of gray and fresh water in the configuration you previously described.  It would not pass any RVIA or ANSI tests either.

[John From Detroit]

Have you figured out why it drained?

Now,, there are basically 3 types of drain valves

1: You pull a "T" handle that is on the end of a rod that goes into the valve body (Local control)

2: you pull a "T" handle on the end of a cable.. which snakes to the valve

3: You push a button/toggle a switch

if you have type 2: Is it POSSIBLE that a 2nd cable goes to the fresh darin

If you have #3, a cross circuit?

Or (And this is likelyhood #1) did you forget to close the fresh water drain so the two tanks both draining had nothing to do with each other) Please don't ask how I know of that one)