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Question: Full Fresh Water tank bulging!

July 02, 2013, 12:59:07 pm

   Since the tanks have been out of our coach most of the time we have owned it while I have worked on more or less rebuilding the basement, I have not had the occasion to have a full freshwater tank before now. But in recent days as I've been testing the systems, I have filled the tank completely full, and was alarmed to note that there was bulging, both on the top of the tank as well as the tall vertical side that would normally be hidden by the water heater. I realize given the nature of the flexible polyethylene material of which the tank is made, there is certain amount of flexibility involved but I am wondering if I should perhaps add a support to cut the span of that tall vertical side in half... What do you think? Non-issue? The top bulging I think is just trapped air because my overflow system allows the level to be higher than the factory setup. I don't plan to travel with it that high... my idea is to fill it full and then put a few gallons in the black tank when hitting the road so that the tank would have the normal amount of fulness. Any thoughts or suggestion would be welcome.
Don

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Re: Question: Full Fresh Water tank bulging!

Reply #1 – July 02, 2013, 01:05:38 pm

I think you are a rock star. :-). Your perfectionist tendencies surely have delayed your fun. With or without brace I hope you can hit the road soon .

Why not at this point?

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Re: Question: Full Fresh Water tank bulging!

Reply #2 – July 02, 2013, 01:30:18 pm

Tis the nature of the beast.  The polyethylene gasoline tanks carrying 120 gallons of fuel under the deck of my boat do the same thing.  Ten years of jumping waves offshore and they're fine. 

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Re: Question: Full Fresh Water tank bulging!

Reply #3 – July 02, 2013, 01:42:15 pm

when ever I had flexible tanks that bulged when full I just put a row or two of 1/2" wide polyester strapping or banding around them.It dosen't cut into the tanks and it makes them self supporting. Gam

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Re: Question: Full Fresh Water tank bulging!

Reply #4 – July 02, 2013, 01:50:42 pm

There are an awful lot of 20 + year old coaches running around with those bulging tanks. I have never heard of a failure. You might create a problem installing braces where friction would wear away the tank wall. Sometimes "if it ain't broke, don't fix it" really does make sense.

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Re: Question: Full Fresh Water tank bulging!

Reply #5 – July 03, 2013, 02:23:39 am

Ours (same year/model as yours) bulge a bit too.  Can't have that much flat area in a tank and not have it bulge some.  They hold up quite well unless something makes a hole in it.

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