City water and onboard 12v system

[Sailor now Trailer]

We have a 2016, 21C that is leaking water into the area near the water pump, next to the bulkhead and the "hull' of the trailer. We had noticed the pump would cycle with a short on/off which indicates a leak somewhere, which I believe must be what I have described. The problem is we are currently hooked into city water at our campsite and there is still water accumulating, not a great deal, but enough to soak into a synthetic chamois which I wring out a couple times a day. My questions are, how are the two systems tied together, and where is that junction located? The leak must involve both the city water and the 12v water system, and be located near the area where the water is pooling, but I haven't been able to find where all of it ties together.
Has anyone else had a similar issue that can offer insight into solving this ?
Thanks in advance.

[Steve Clark]

Hi Trailer, When the check valve on the water pump fails and you are hooked up to CITY WATER, the water back flows and fills up your fresh water tank. When the fresh water tank is full and the city water is still turned on, the fresh water tank overflows and spills out of the fresh water vent. The water is under pressure and may be backing up on the hoses leading to the water pump. I would check the level of your fresh water tank. Is it full? Overflowing? How much water was in the fresh water tank before you hooked up to city water? The Check Valve can be replaced, but it may also be time for a new water pump! Easy to replace!
Good Luck!

[Sailor now Trailer]

Thanks Steve, I will check to see if there's water seeping into the tank. There isn't any water I have noticed, other than described in the post.

[Viajante]

All of the piping except for the pickup hose from the tank to the pump is pressurized by both city water and the pump. So a leaky connection in any pipe will leak whether the pump is on or whether connected to city water. And as Clark said, if there is a bad check valve in the pump water may even backflow to the tank under city water pressure.

If you turn the pump off between uses there will be less leakage than when city water pressure is on all the time.

There is another check valve at the city water connection to prevent the pump from pushing water back out of the city water connection.

[Sailor now Trailer]

This isn't any kind of back-flow issue, no water back flowing into the tank. What I'd really like to know, is how to access the space where all the plumbing ties the city and 12v tank water together?That is where I suspect the leak occurs.

[Vermilye]

Originally Posted by Sailor now Trailer

This isn't any kind of back-flow issue, no water back flowing into the tank. What I'd really like to know, is how to access the space where all the plumbing ties the city and 12v tank water together?That is where I suspect the leak occurs.

If your 2016 is built the same as my 2017, the connection between the city water & the pumping system is under the driver's side rear seat. There is a "T" in the city PEX water line where the pump output connects.

[rubicon327]

Originally Posted by Viajante

All of the piping except for the pickup hose from the tank to the pump is pressurized by both city water and the pump. So a leaky connection in any pipe will leak whether the pump is on or whether connected to city water. And as Clark said, if there is a bad check valve in the pump water may even backflow to the tank under city water pressure.

If you turn the pump off between uses there will be less leakage than when city water pressure is on all the time.

There is another check valve at the city water connection to prevent the pump from pushing water back out of the city water connection.

Great explanation.