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Bulging water tank


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Hey :)


I use a Coachman Mirada and have come across a problem.


Last year i could attach a hose to the water tank and pump in the water until it is full with no problems.


I came back to it this year and flushed out the anti freeze and filled the tank about half way. The water still tasted sort of chemically so i emptied the tank using the showers and taps and toilet.


I then noticed the tank looked squished, as if the air had been pumped out slightly. I had never seen it do this before and came back to it the next day and it was back to its original shape.


I then connected a hose and started filling it again. It got to 3/4 full and i noticed some creeking noises. I looked at the bed upstairs and the floor was bulging! I ran down and disconnected the water.

The tank had completely bulged from what looks like too much air.


I left it over night and the tank had got back to its usual shape. There is a hose next to the tank which i can feel air coming out.


I am not sure why i am having an issue with displasing the air from the tank now when i could happily fill it to full before.


Any ideas whats changed?



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The 'Breather' must be blocked, all tanks need a breather to allow the displaced air to escape, and to to allow an overflow of excess water, you need to find the breather pipe and clear it, before trying to put water in again. It must be pretty solidly blocked as the internal pressure must have been pretty high to bulge the floor ! lucky you were on the spot, otherwise it could have 'popped'.

I have NEVER put anti-freeze in my Motorhomes Fresh water tank !!! I know this is normal in the USA, and they market 'Potable' anti-freeze, but not in the UK. That I have seen anyway. Ray


ps. a Coachman Mirada is a US RV right ?.... Upstairs ???

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I agree. If the breather is a tube, it may be kinked somewhere, or have something heavy squashing it. Don't understand the comment about pumping in water. Is there some kind of transfer tank involved? I've only ever filled with a hose through the filler point, so air escapes as water enters. Don't understand why the tank was emptied using taps/shower. Isn't there a drain-down facility on the tank?
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Thanks, i will definintely have a look at this breather pipe!


Also sorry not anti freeze as such it was this stuff recommended to stop the pipes from freezing during the winter.


I was very scared it very will bulge!


And it is a US RV but upstairs i mean, up the stairs from the outside where the water tank is

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I mainly wanted to empty the water through the taps to get cleaner water running through and also down the toilet to wash out any 'remains' that may have got stuck from last year. The rest of the water i did use the down-drain facility.


Also we connect our hose to the side of the RV and it sucks up the water using a pump. I cannot pour the water in directly (no way i can find myself anyway)

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