Is there an Overflow from the fresh water tank

tmsnyder · May 19, 2016, 11:32 PM

I'm new to RV's , filled up my fresh water tank the other day to find after filling quite a while, the monitor worked well and showed the tank filling. Got it up to all 4 lights illuminated, showing full. I let it run a while more to see what would happen when it was completely full and found that it appeared to be raining underneath the entire area where the tank is after the tank filled up. I was expecting it to overflow from the little breather hole next to the fill hole.

So does that mean my tank has a hole or a break on the top of the tank or is this normal?

beaverman · May 20, 2016, 12:06 AM

actually if all is working well it should flow back out of the hole that the hose was in, the breather hose is usually way too small to even let enough air escape from a fast filling hose and the main spout will burp, sounds like you either have a missing breather hose or a hole in the top of the tank

TerryH · May 20, 2016, 12:19 AM

There are a few topics on site regarding the inaccuracy of the tank(s) monitoring systems. 4 lights illuminated during filling - provided - the sensors are reading correctly actually means your tank is 3/4 full and filling.
As for rain underneath when the tank is full and connected to city water and still filling, the overflow has to go somewhere. Eventually it will go downhill, across the tank top and over the edges. Rainfall.

Rickf1985 · May 20, 2016, 08:56 AM

It depends on what type of tank and fill system you have. Mine has a pressure fill system and when full it overflows out of a hose on the passenger side underneath. I do not have any way to gravity fill mine though.

tmsnyder · May 20, 2016, 11:21 AM

This is what I'm afraid of, the tank is / should be completely sealed except for the gravity fill port and the vent tube. The vent tube is right next to the gravity fill hole. The water didn't come out vent or back up the fill tube when the tank was full, it ran out onto the ground all over the entire tank area underneath the coach. It was about a 4' by 4' area at the rear of the coach. Like rain, not like coming out of a hose.

Oh well, I was never going to drink that water anyway. If the tank is leaking on top and potentially getting road mist water and dirt into it I'm definitely not drinking it but it's fine for everything else.

More crawling around and looking is in order obviously.

Thanks for the insights.

Quote from: beaverman on May 20, 2016, 12:06 AM
actually if all is working well it should flow back out of the hole that the hose was in, the breather hose is usually way too small to even let enough air escape from a fast filling hose and the main spout will burp, sounds like you either have a missing breather hose or a hole in the top of the tank

Rickf1985 · May 20, 2016, 11:40 AM

It may be as simple as a missing vent hose but you definitely need to find it. There will also most likely be water damage from the leak from before, no need to make it worse. Find the problem and fix it.

tmsnyder · May 20, 2016, 02:41 PM

Thanks Rick

Quote from: Rickf1985 on May 20, 2016, 11:40 AM
It may be as simple as a missing vent hose but you definitely need to find it. There will also most likely be water damage from the leak from before, no need to make it worse. Find the problem and fix it.

engineer bill · February 15, 2018, 04:10 PM

I recently acquired a new (to me) older Winnebago. When I filled the water tank using city water through the tank fill fitting, after it filled, it started peeing out the overflow hose. So far so good. I turned the hose off and disconnected it and turned the valve from the fill setting to run.

But the overflow continued for at least fifteen minutes-maybe ten or twenty gallons of water wasted on the road. Something is not right. And, I never had this problem before on my '89Winne.

I'm thinking I should a) turn the hose bib way down to fill slower, b) use my city water pressure regulator on the hose and the pressure turned way down.

Any other suggestions?

Rickf1985 · February 15, 2018, 05:38 PM

My 89 drains for quite a while after filling up but it is a fully enclosed system, not a gravity fill. I think a lot depends on where in the tank the overflow is and if the tube goes down into the tank which it shouldn't but who knows. How old is this one and is it like the 89 with a totally enclosed system with no gravity fill?