Toilet Overflow

City water provides potable water to cold water plumbing lines then to water heater which then provides water to hot water plumbing lines.

Hot/cold plumbing lines have NO direct connection to waste tanks (grey or black)except thru faucet/shower drains (to grey) or toilet (black)

Grey tank is separate.no overflow to black tank or any place (NO Overflow)

Black tank is separate (No Overflow)

50 guests several KIDS.......toilet overflowed because folks/kids did not understand how to use toilet. Black tank filled up and last kid using toilet filled it even higher until water ran out onto flow (" most of water that dumped onto floor was fresh")

Only problem you have is way too many using facilities during short time period, not rv toilet trained, and a mess on floor

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ScottG wrote:
The city water inlet is not directly connected to the grey tank.
Unless they are both using the same tank (rare), the grey and the black tanks are not connected unless you do something screwy with the drain vavles.

I did notice that the gray drain valve was left open by the pump truck operator. So fresh water ran out of the exterior drain cover as soon as I removed it. But the black valve was closed so I can't figure how it would have backed up thru the black valve.

Turtle n Peeps wrote:
I'm not getting what you're saying?

The gray and black tanks are two separate systems? At least on every trailer I have seen?

As I have been told, on some designs the gray will overflow into the black tank when full. At least that can be true on some class A's. All I can say is that as soon as I shut down the well pump the overflow stopped. The tanks were pumped out the day before the picnic so were empty at the beginning of the day. I'm unclear on how the city water connection flows into the gray tank. Now that I know its happening I can hear the well pump clicking on about every 5 minutes when connected to the city water inlet.

Looks like I'm not the only one that doesn't know what's going on? :B

I'm not getting what you're saying?

The gray and black tanks are two separate systems? At least on every trailer I have seen?

The city water inlet is not directly connected to the grey tank.
Unless they are both using the same tank (rare), the grey and the black tanks are not connected unless you do something screwy with the drain vavles.