Have you had to do this???

[Sogr8ful]

My holding tank sensors are not working. How can I know when my fresh water tank is full? I don't want to blow it up.

[slickest1]

Your fresh water tank will have an overflow. When it gets full water will flow out the overflow tube and you should be able to hear it or if you watch under the rv you will see it running out of the tube.

[Bob1340]

Ditto with the Gray and Black tank. Eventually they'll fill and back up causing your dog to ask to sleep outside. My black tank sensor works poorly. But on mine when I flush I can look straight down into the tank and see how full it is.

[BentlyRV]

Originally Posted by slickest1

Your fresh water tank will have an overflow. When it gets full water will flow out the overflow tube and you should be able to hear it or if you watch under the rv you will see it running out of the tube.

x2

with the overflow, she will never 'blow!'
Experience in monitoring the other tanks depends upon your coach and what routine you get into when flushing and cleaning your black & grey tanks! No matter what your routine, you'll probably see inconsistent sensor readings especially on the black and grey tanks!

Best wishes,
Tim

[ga traveler]

You are correct in that you can blow up your tank. I have repaired several fresh water tanks. The hose to the top of the water tank is not a overflow hose, it is a vent hose. If you did not let air in to the top of the tank, your tank would build up a suction from the pump and the tank would collapse. If you have a gravity fill with a cap and you use a hose to fill the tank, you have little chance of doing any harm. If you have a pressure fill and divert the pressure water to the tank, There is a good chance of doing damage. always look at the tank and shut off the water when almost full. If you have both types, then take the fill cap off when filling with the pressure fill. Shut off the hose as soon as you see water coming out of the gravity fill.

[Podivin]

Fill the fresh water tank SLOWLY and you'll be fine.
The vent line will allow water to flow out, but it can't let water out as fast as a full pressure water hose can put it in.
If it takes about 30 minutes (or more) to fill the tank from empty, that's probably about the right flow rate.

[Notayurt]

Agree completely with the overflow/vent tube releasing overflowing water when filling with a fresh water hose. But -- hey, my fresh water tank is translucent, so I can just open up a basement bay and watch and monitor how full the water tank is while I'm filling it.

I rarely run with more than a half tank of fresh water when I know I'll be camping with hookups withing a few days. I figure it doesn't make sense to carry the extra water weight of a full tank when we use so little while on the road between planned stops. Good luck.