Freshwater System question

Fantastic ! I knew there had to be a vent, but it wan't clear how or where it was... Thanks to All.

I am learning more about RV type system than I really wanted to know...

Bob

Just like any tank.......waste water holding tank, fuel tank, fresh water tank etc. they need a vent so that as you add fluid in the air can get out of tank as it is displaced by the fluid and so that air can get back in as fluid is drawn back out.

Some fresh water tanks with gravity fill have a vent line that terminates inside the gravity fill tube hatch.
Some have a vent line that is just attached high up on frame
The fresh water tank should have a vent connection on top of tank..just run a small hose up above tank...no kinks/bends/low spots so water can't get trapped and block the vent action

Drill a small hole, maybe 1/4" or 3/8", at the top of the tank and run clear plastic hose from the hole to the outside of the trailer.

Even tanks that don't have a gravity fill (like mine) still have a vent on the top of the tank.

Normally in the water fill hatch. Enlarge one of these photos. You should see small screen device
Water hatches

Bob,

Our trailer freshwater tank has a vent tube that connects to the fill inlet.

Steve

On mine, it has a "gravity" fill inlet. As part of that assembly, there is a little hole with a fine screen mesh filter that lets air in.

For example, check here:

http://www.pplmotorhomes.com/parts/rv-pumps-water/rv-gravity-water-fill-hatch.htm?utm_source=google&utm_medium=partsshopping&utm_campaign=partsfeed&gclid=CMCCsL_tzboCFU8V7AodeWkAKw