How are folks handling venting on interior water tanks?

[belfert]

Currently, my water tank is in a bay and the vent is two pieces of 1 1/4" tubing with an elbow connected to what is typically the fill on the tank.  The end is stuffed with a stainless scrubbie to keep insects out.  It is unlikely water would ever get that high and it would just drain into the bay if it did.

I am thinking about installing water tanks under the bunks inside and converting the current water tank to a grey tank.  How do you folks handle venting so water doesn't get into the bus?

[gumpy]

I put a fitting in the top of the tank and attached a piece of 1/2" PEX to it and ran it through the bay floor. I then stuffed the piece of stainless scrubbie in it.

When the tank is full, it runs out below the bus.

[JackConrad]

    Our water tank is in the bay, but I wanted the vent outside of the bay in case I overfilled the water tank. I came out of the top of the water tank with 3/4" PVC through 2 90 degree elbows, then a length of 3/4" PVC through the floor. Under the floor, another 90 degree elbow pointing towards the back of the bus. I stuffed a copper scrubby in this elbow and put a couple stainless steel screws through the elbow into the scrubby to keep it in place. No problems in over 9 years. This works for us, YMMV
   You could probably run your vent through the floor under you bed into the engine compartment.  Jack