Fresh tank vs gray

[jandna]

Is there a difference in the construction of the fresh and gray water tanks?
I can't find a fresh tank in the size that I am looking for. Is it possible to use a tank marketed for gray water as my fresh water tank?

Thanks!

[jandna]

I want to install my fresh water tank beneath the subfloor...

[robwok]

Potentially. Different plastics are used for the different tanks. The problem is that some plastics can impart an off taste or absorb chemicals and give off tastes.

For example, the plumbing in your house may be pvc and cpvc. Pex is cross linked polyethelyene, and milk jugs and most other fresh water supply are polyethelyne. I don't know about ABS, but I believe it is safe as well - you can always ask a tank manufacturer.

As far as below the floor, I would be cautious using a black plastic tank below the floor. It's hard to see if you have mold or mildew growing in it. It's definitely possible, but you'll want to make sure you can inspect it, and, since the siphon portion of the connection will be near the bottom, it's possible your inlet could freeze - robbing you of water. The other situation is that the water can be freezing cold. My tank is inside, above an insulated floor, with another layer of bubble wrap directly under the tank. It's under the bunk bed, and when it's cold outside, you can barely wash your hands under the cold water. (great for drinking though). You won't be able to add much insulation between the tank and the belly pan. I have a layer of foil bubble wrap below the gray and black tanks I installed, but that's it. There was no more room than just a single layer.

Rob.

[pbearsailor]

You want a tank you know is safe for drinking water. Not sure many grey tanks would be certified that way. There would also be that large drain fitting that wouldn't be needed.

My fresh tanks are mounted below the subfloor. Valterra 24 gallon tank

Welcome to the forums! What trailer do you have?

Cheers,
Steve

[Thalweg]

You might contact one of these places. They can make custom tanks and will be able to tell you what is suitable for potable water.

Tanks
Custom All-Rite Holding Tanks - RV Holding Tanks - All-Rite.com

[HowieE]

Try them
RV Water Tanks | RV Fresh Water Tanks | RV Potable Water Tanks

[Protagonist]

Originally Posted by robwok

For example, the plumbing in your house may be pvc and cpvc. Pex is cross linked polyethelyene, and milk jugs and most other fresh water supply are polyethelyne. I don't know about ABS, but I believe it is safe as well - you can always ask a tank manufacturer.

Only two colors of ABS are considered food-grade: black and natural beige. However, ABS is not really recommended for use in potable water tanks. It's used more often in food processing machinery for surfaces that will come in contact with food or beverages.

As other posters have noted, ABS is dark in color, which makes inspection somewhat problematic. If you use an ABS freshwater tank, expect to have to disinfect with chlorine more often than your owner's manual recommends, to make sure you get no unwanted growth in your tank.

[Belegedhel]

If you want some tanks that will fit below your floor, inside your frame and not hang below the bellypan, then I would suggest investigating the tanks offered by Vintage Trailer Supply for use as grey water tanks. They are made of polyethylene, which is the same material that fresh water tanks are made of. They are manufactured without any standard inlets/outlets, so you can request custom fittings to be added to your specs.

One thing I would recommend, is installing a "clean out" port in the tops of your tanks so that you can occasionally run a wet-vac into the tank from above the floor and suck out every last bit of stuff that might be growing in there.

Good luck!

[jandna]

Thank you for all of the info guys!

It is very much appreciated.

I think we will have to get a custom fresh water tank made for below the subfloor. The grey tanks on vintage trailer supply are a little too big for the space between the iron support beams.

We have a 1962 Overlander 26'.