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Blue Ribbon · 02-28-2011, 07:36 PM

As usual, I was quite glad to see my Motorhome magazine today, and one of the first columns I read is "Quick tips from our Readers" because there are a lot of good ideas, which you say, "why didn't I think of that." "It is so simple."

Well, I had the same problem as James Briner (from Bradenton, Fld) who wrote this quick tip. I was loosing 10 to 15 gal. of water from our tank through our vent, and since we primarily camp in state parks, we need all the water we can get. So, like he suggested, I installed a ball valve in the vent line, and I did not open the valve until we were set up and level, and we quit loosing water. I've had the valve for 4 1/2 years.

Last summer, probably on a 3 day holiday, I was blocking the camp loop, while I was getting water, and of course was in a rush. After about 15 minutes I heard a loud explosion, really like a cherry bomb, and I started loosing massive amounts of water out of the bottom of the RV.

Now, I don't have to tell you what happen. Normal water pressure is about 40 PSI and with no air vent, well....... $3,200 to fix. Back cap had to come off, sub flooring had to be replaced, and the sad part is I went from having a 75 gal. capacity to a 58 gal. capacity, because the tank that (the now out of business National) used, was no place to be found.

Yes, I still have the valve, but I don't think I will ever forget to open or close it. There can be just as much of a problem, if once you get level, and you do not open the valve and you continue to draw water from the tank, ..... I venture to guess that when you draw out 50% to 60%, the tank is probably going to split, or if you are real lucky a hose will give way, but the vinyl hoses that are typically used will withstand quite a lot of pressure/vacuum.

The valve is a great idea, but NEVER, NEVER forget where it is set when you are filling your tank or using water from your tank.

Its Paid For · 02-28-2011, 08:18 PM

Great advice for everyone, thank you. However, reading your story is going to keep me up tonight, the horror. Lol

jeepfreak · 03-04-2011, 09:57 AM

In my last coach ( Rexall Arebus) the fresh water tank was under the bed and had shut off valves for every line , including the vent/over flow. I started filling and went on to check the tire pressure and other stuff and much to my horror realized that nothing was coming out the overflow. Rushed inside lifted the bed flew to the house and turned off the water. The tank holds 100 gals and I bet there was at least 125 in there. It didn't rupture .This all happened because I didn't realize the vent/overflow valve was a t connection with one leg going staight down and when I turned the valve handle I shut off the bottom port. I was very lucky and now if I don't know where or what something does, it goes back to the postion I found it in until I KNOW what it does!

Ray,IN · 03-04-2011, 11:37 AM

That would pretty-much ruin one's day. A magic-marker warning on/near the water fill cap sounds logical.

Gary RVRoamer · 03-04-2011, 05:06 PM

A much safer idea is to re-route the vent/overflow line so that the outboard end is higher than the tank. That way, it can still overflow and/or vent, but the tank will stay full.

A less good method but often easier is raise one section of the outlet line up above the tank. The drawback of this mnethod is that once water starts to flow, it starts a siphon action that continues draining the tank. But if you don't overfill, the high loop will stop water from sloshing out.