How to know when the freshwater tank is full?

[TenOC]

I have been RVing since 1979. During this time, I have owned a dozen or more travel trailers and or 5th wheels RVs. Each of these RVs had a gravity freshwater fill port with a vent/overfill drain at a location that was easy to see when the freshwater tank was full. We boondocks more than 75% of the time; therefore, it is very important to have a full freshwater type.

Our current 5th wheel does not have a gravity freshwater filled port and the vent/overflow drain is located near the wheels where it is almost impossible to see when the freshwater tank is full and water overflows. I thought about running some type of hose, connected to the existing vent/overflow drain to someplace such as near the City water hose connection so I can see when the freshwater tank is full. Do any of you have a better suggestion?

I’m not trying to address the problem of siphoning water out of the freshwater tank. There are other threads which address the siphoning problem.

[Daryles]

We have an inline water meter we put on the hose.
From bone dry empty (dewinterizing) it takes about 65 gallons. Freshwater tank, pipes and water heater.
Normally filling the freshwater tank takes about 42 gallons. I usually fill it until water overflows out the vent. With the slides out I can't see the vent at the rear but I can see the water running down the sides dripping on the ground and shut off the valve.
Keeping the water in the tank while driving is another challenge.
If you take a right hand clover leaf exit coming off the highway, the centerfugal force will push the water out the vent overflow. You arrive with less than half a tank.
Put a Rubber boat drain plug in the freshwater vent to prevent this.
Just don't forget to remove it upon arrival or you will collapse your freshwater tank when you use your water and air can't get into the tank.

[OB-1]

I've thought of this for several years on how to know when fresh water tank is full from the filling Port. It would require to connect/tap off the fresh water drain hose. You would install an extra flexible clear hose and use it like those big coffee urns (5gal type) you find in restaurants/diner's. Just know where the top of the fresh water tank would lineup on the outside wall on the RV and have the top of the hose about 6 inches higher past the top of tank on outside wall. The water level will equalize between the tank & hose taped from drain hose. Leave top of hose open.

May be hard to visualize this but again, if you look at those restaurants or diners that have them 5gal coffee urns you'll now what I mean.

[RMcNeal]

Originally Posted by OB-1

I've thought of this for several years on how to know when fresh water tank is full from the filling Port. It would require to connect/tap off the fresh water drain hose. You would install an extra flexible clear hose and use it like those big coffee urns (5gal type) you find in restaurants/diner's. Just know where the top of the fresh water tank would lineup on the outside wall on the RV and have the top of the hose about 6 inches higher past the top of tank on outside wall. The water level will equalize between the tank & hose taped from drain hose. Leave top of hose open.

May be hard to visualize this but again, if you look at those restaurants or diners that have them 5gal coffee urns you'll now what I mean.

Kind of like a spirit level. The water level in the tank and hose will be the same height.

[DutchmenSport]

Your idea would work provided you do not have any loops or kinks in the new hose that would create an air lock or hold water anywhere. If you create an air lock or if the new hose holds water, it will create a vacuum and your fresh water tank will never fill correctly (if at all).

[rohrmann]

I just stand near the vent when filling and when water exits the vent, I turn off the water. Excess water then drains from the vent and the tank is full.

[bshgto]

Originally Posted by rohrmann

I just stand near the vent when filling and when water exits the vent, I turn off the water. Excess water then drains from the vent and the tank is full.

Sounds pretty darn simple to me.

[Ram Montana High Country]

I stand near the shut off. I can hear and see when it hits the ground.

[Todd & Mary]

Our vent is very close to the filling point. When boondocking I fill till the water comes out the vent. Which is actually quite q while after the tank reads full.