Both Gray & Black Tanks Overflowed

[Scatman]

Just picked up a 2017 Coachmen Freelander 26 Class C this winter. Used 1st time past week in NC. Everything was great until waking up this morning with water everywhere. On city water , both black and gray tank were FULL! Sink overflowed and toilet full to top. Went to bed with both tanks mostly empty, dear wife used toilet during night but that was it. Can’t figure out what caused it. Tonight I put water in fresh hold tank and will use pump. Any ideas????

Scatman
USAF Retired
Fully Retired Now
Loving Lifestyle

[Bob K4TAX]

Sounds as though the connection to city water may not have had a pressure regulator in the line. Excessive high pressure can override the backflow valve in the 12V pump. This is not uncommon. That will allow the undesired filling of the freshwater tank. A leaking faucet or toilet will fill the grey and black tanks in short order. Excessive city water pressure will contribute to this. Always use a pressure regulator at the water source before any hose that is connected to the RV.

I prefer to fill the fresh water tank with city water and use the 12V internal pump for all of my water needs. If you hear the pump cycling on and off, you have a dripping faucet, dripping shower, or leaking toilet. The grey water and black water tank contents had to come from somewhere.

Also, don't trust those silly tank-level indicators. They are known to be largely in error. Always dump and know the status of one's tanks. Relying on instrumentation is great, as long as you know it is accurate.

Bob

[dalford]

Couple of questions… Toilet full to top with fresh water, right? Black water should not be able to flow up thru ball valve to fill toilet.

Are you sure black tank is full? Can you flush that water that was to the rim?

The black tank and grey tank are isolated. Even if the fresh water was back feeding thru the water pump it would not fill the grey tank. Plus if the city water back fills thru the water pump it would cause the fresh water tank to overflow. The fresh water tank has an overflow hose.

The only way the grey tank will overflow the sink is if the water is left on.

It sounds like 2 issues. 1st is the toilet flush valve has a slow leak thus filling the toilet. 2nd the water in bathroom or maybe kitchen sink left on.

Something does not make sense here?

[Scatman]

Yes, black tank full, dirty water in toilet. Had to glove it up and dip out both toilet and sink to move unit to dump station. Both tanks indicated full and both dumped as if full. It’s possible toilet flapper/water valve stuck and slowly filled black tank over 4-5 hours, but sink faucet was not dripping or on, so don’t know how the gray filled. One RV’er indicated the Grey tank may be connected to black tank with high mounted crossover pipe to give more gray capacity. Researching my books to see if possible. Should also say fresh water tank did not fill during this early morning adventure. Thanks!

[MR.M]

Originally Posted by Scatman

Just picked up a 2017 Coachmen Freelander 26 Class C this winter. Used 1st time past week in NC. Everything was great until waking up this morning with water everywhere. On city water , both black and gray tank were FULL! Sink overflowed and toilet full to top. Went to bed with both tanks mostly empty, dear wife used toilet during night but that was it. Can’t figure out what caused it. Tonight I put water in fresh hold tank and will use pump. Any ideas????

Scatman
USAF Retired
Fully Retired Now
Loving Lifestyle

Could you have hook your city hose to the black tanks flush by mistake ? not much makes since . gray tank and black tank separate . with out water running in sinks or shower grey should not fill . with out toilet running no way to fill black tank . no flappers in rv toilets to leak by you would see water flowing into the toilet . fresh tank didn't fill so pump check valve ok .was toilt full but black tanks empty ? that would indicate a leaky valve for toilet since the ball and seal would keep the water from going into black tank .. think your missing something major you did .
Do you have andersen valves in your water bay ? maybe you didn't have them in the correct position

[Larry-NC]

Originally Posted by Scatman

Just picked up a 2017 Coachmen Freelander 26 Class C this winter. Used 1st time past week in NC. Everything was great until waking up this morning with water everywhere. On city water , both black and gray tank were FULL! Sink overflowed and toilet full to top. Went to bed with both tanks mostly empty, dear wife used toilet during night but that was it. Can’t figure out what caused it. Tonight I put water in fresh hold tank and will use pump. Any ideas????

Scatman
USAF Retired
Fully Retired Now
Loving Lifestyle

I don't understand. The sinks will never overflow from a full gray tank. The shower (much lower) always overflows first. The only possible exception could be in a 5er with the shower on the upper floor. (I don't think anyone makes one.)

This isn't an early April Fool's joke is it?

[NMWildcat]

Originally Posted by MR.M

Could you have hook your city hose to the black tanks flush by mistake ? not much makes since . gray tank and black tank separate . with out water running in sinks or shower grey should not fill . with out toilet running no way to fill black tank . no flappers in rv toilets to leak by you would see water flowing into the toilet . fresh tank didn't fill so pump check valve ok .was toilt full but black tanks empty ? that would indicate a leaky valve for toilet since the ball and seal would keep the water from going into black tank .. think your missing something major you did .
Do you have andersen valves in your water bay ? maybe you didn't have them in the correct position

This.
Sounds like the city water hose was connected to the black tank flush and filled the black tank (happened to my BIL).
As far as the sink filling, some sinks do drain into the black tank. Perhaps yours does.
As far as the gray tank being full also, I don't have any good ideas on that one.
I know some RVs, the only connection between gray and black tanks is the vents (mine connect into one vent going to the roof), but the connection would have to be fairly low for water to flow from one tank into the other and you will still have tons of water coming out all the drains.
Let us know what you find out.

[Larry-NC]

Originally Posted by NMWildcat

This.
Sounds like the city water hose was connected to the black tank flush and filled the black tank (happened to my BIL).
As far as the sink filling, some sinks do drain into the black tank. Perhaps yours does.
As far as the gray tank being full also, I don't have any good ideas on that one.
I know some RVs, the only connection between gray and black tanks is the vents (mine connect into one vent going to the roof), but the connection would have to be fairly low for water to flow from one tank into the other and you will still have tons of water coming out all the drains.
Let us know what you find out.

Same question: If the toilet is overflowing, how does water rise high enough to overflow the sink?

Second question: Didn't your BIL hear the water running through the hose, and not stopping and turn the water off?

[NMWildcat]

Originally Posted by Larry-NC

Same question: If the toilet is overflowing, how does water rise high enough to overflow the sink?

Second question: Didn't your BIL hear the water running through the hose, and not stopping and turn the water off?

Higher drains could overflow depending on volume of water coming in compared to volume of water allowed out through drains. Toilets flaps are usually closed, restricting outflow, forcing it elsewhere. Just a thought.
My BIL is even more deaf than I am and he had only used his RV three times so was still unfamiliar with it. They had quite the mess to clean up. Thankfully my SIL saw the water on the floor before the tank or toilet actually exploded.
The OPs situation as described doesn't make a lot of sense yet to all of us arm chair quarterbacks. Will be interesting to find out the rest of the story.

[Reverse_snowbird]

Originally Posted by Scatman

One RV’er indicated the Grey tank may be connected to black tank with high mounted crossover pipe to give more gray capacity. Researching my books to see if possible. Should also say fresh water tank did not fill during this early morning adventure. Thanks!

It's possible that the sink is connected to the black water tank. Ours is. We accidentally left the bathroom sink on and the black tank filled and overflowed the sink. Luckily the tank was clean. However the black tank bowl never filled up.

Of course, it's also possible you have a leaks in the plumbing that filled up the tanks.

Did you buy this from an individual or a dealer? Since it's a used unit, it's possible that the former owner made modifications to the plumbing to give it more grey or black water capacity.

[glen1971]

Tank drain valves left open, with a main drain valve closed could explain both tanks filling? With one tank filling, the second tank could fill from the drain upwards. But that's just a guess.

[stephndudb]

Originally Posted by glen1971

Tank drain valves left open, with a main drain valve closed could explain both tanks filling? With one tank filling, the second tank could fill from the drain upwards. But that's just a guess.

This. Is there an added gate valve at the very end of the drain pipe? Couple that with the water hose accidentally connected to the tank flusher and you'd fit the scenario.

[Larry-NC]

Originally Posted by stephndudb

This. Is there an added gate valve at the very end of the drain pipe? Couple that with the water hose accidentally connected to the tank flusher and you'd fit the scenario.

Bingo!

I never understood why people would buy that twist-on thing when it's so easy to repair the gate valves.

[dalford]

Originally Posted by Larry-NC

I don't understand. The sinks will never overflow from a full gray tank. The shower (much lower) always overflows first. The only possible exception could be in a 5er with the shower on the upper floor. (I don't think anyone makes one.)

This isn't an early April Fool's joke is it?

Not necessarily true.. how do I know..lol..

I left the bathroom sink on and only discovered it when water was running out of the RV (5th wheel). The shower does not have a j-trap. It has a one way valve (I forget what they are called) that only allows water to drain out but not come in. Thus my sink overflowed.

Now, my sink is obviously above my toilet but my toilet did not fill. I don’t know how the op’s toilet fill with black water?

[Reverse_snowbird]

Originally Posted by Larry-NC

Bingo!
I never understood why people would buy that twist-on thing when it's so easy to repair the gate valves.

Because it's not always easy to repair the gate valves in some rigs, and to have someone do it can get expensive.

Most of the time our gate valves are fine, but occasionally they leak driving down the road and a gate valve at the end eliminates 'surprises' when we go to dump.

I hope the OP shares what the problem/solution was. It's a bit of a head scratcher.

[DougW]

My guess is that the black and grey share a vent line, the OP accidentally connected the fresh water to the black flush and when the black tank got full the water went up the vent line until it reached the pipe coming from the grey than then ran back down until the grey tank got full.

[Larry-NC]

Originally Posted by dalford

Not necessarily true.. how do I know..lol..

I left the bathroom sink on and only discovered it when water was running out of the RV (5th wheel). The shower does not have a j-trap. It has a one way valve (I forget what they are called) that only allows water to drain out but not come in. Thus my sink overflowed.

Now, my sink is obviously above my toilet but my toilet did not fill. I don’t know how the op’s toilet fill with black water?

HepVo.

Someone did figure out that the OP may have put on one of those twist-on secondary gate valve and then opened the stationary black and gray valves, thus providing a path. I suppose you could to the same thing just using the cap. (When you get ready to dump, close both valves and hold the hose under the cap as you remove it. I've done this without making a mess.)

[NMWildcat]

Originally Posted by Larry-NC

HepVo.



Someone did figure out that the OP may have put on one of those twist-on secondary gate valve and then opened the stationary black and gray valves, thus providing a path. I suppose you could to the same thing just using the cap. (When you get ready to dump, close both valves and hold the hose under the cap as you remove it. I've done this without making a mess.)

Oh, there are several scenarios that would have the same result, but unless the OP figures it out and comes back, it is all just SWAG on our parts

[NavyLCDR]

Originally Posted by Larry-NC

I don't understand. The sinks will never overflow from a full gray tank. The shower (much lower) always overflows first. The only possible exception could be in a 5er with the shower on the upper floor. (I don't think anyone makes one.)

This isn't an early April Fool's joke is it?

Not true. The shower has a duckbill type check valve to keep the grey water (and odor) from flowing backwards through the drain. The sinks have the standard P-traps that do allow water to back flow.

[Larry-NC]

Originally Posted by NavyLCDR

Not true. The shower has a duckbill type check valve to keep the grey water (and odor) from flowing backwards through the drain. The sinks have the standard P-traps that do allow water to back flow.

Attachment 285036

Yes. Dalford mentioned the HepVo valve back in Post #14 and I named it in Post #17.