Pressurizing water tank with onboard air compressor

CruzLiife

New member
Hi,
I’m building out my van and I added an onboard air compressor with 2 gallon tank. I currently have it hooked up to an air chuck and train horns but I heard about using it to pressurize my water tank. I am planning on mounting a 20gal fresh water tank under the van. Anybody try using an air compressor to pressurize the water system? Is it a good idea? How does the compressor know when to shut off? Or am I better off sticking to a 12v water pump? Thanks for any info out there.
 

WOODY2

Adventurer
I'd stick with a 12v pump with built in regulator for several reasons. Cheap, easy to plumb, on demand and no potential oil blow by to contaminate your water source.
 

theblindchicken

New member
Wonder if you can do a setup like fuel cell. Where it's a fuel bag inside a metal container.

Have your fresh water in the sack with the air compressor putting pressure inside the tank, but on the outside of the sack. Would work like squeezing a capri-sun.

Just a thought.
 

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theblindchicken

New member
This works great. Millions of examples exist at homes what are served by a well.
A bladdertank whats practical under a van is likely a hassle to buy or make...
That's the word I was trying to think of.

Checked Fuel Safe real quick, they have a 25 gal water safe bladder... but its quite the price at over $450 and pretty sure thats without a metal tank as well.
 

CampStewart

Observer
Is your compressor oil lubed, or oil less? If oil less than no issue with oil. If oil lubed than a oil seperator and good filter and you are good to go. Is your tank rated to be pressurized, and if so than how much? If it is rated to be pressurized than put an adjustable regulator in a dedicated line to it and you are good to go. You will probably have much better pressure and flow than with the electric pump.
 

SexyExy

Observer
I have done it (non RV application) and it works very well. But, the issue you're going to have is the actual water tank. Most are flat sided and even 5 psi will make it start to bulge out. I did experiments and found even the plastic fuel jugs that motocross racers use will start to deform and expand at 5 psi....and those had good thickness, ribbing and rounded edges. I'm afraid a rectangular water tank with flat sides may not like the pressure at all.

We use traditional round steel tanks (think air tank) to hold the water then pressurize it to around 35 psi. This was then used to clean and spray off concrete pumps, concrete tools, hoses, etc.

If you could find a stainless steel air tank that you trust drinking water out of, this would be the best case solution for a pressurized water displacement system as it is designed for the pressure you'll require.

It would be much easier for your application just to use a quality 12 volt water pump.
 

dman93

Adventurer
Even filtered and oil-less, I wouldn't spray compressor output into MY drinking water, unless there was a bladder. Even home systems, as far as I know, use water pressure against the bladder, not outside air.
 

SoCal Tom

Explorer
Will you be using a pressure rated vessel? To get a decent flow rate you will probably need over 10 PSI ( and more likely 25 or so).
Tom
 

hogasm

Observer
I had an old camper that had this setup. The camper rotted away but the pump is still on the shelf.

Pump is not strong enough to work train horns but kept decent water pressure. Never did check out what the working pressure was.
 
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