I need a plan - black, grey and fresh

[Marlboro Mafia]

My '61 Safari has a small black water tank uner the toilet, and a long galvanived looking fresh water tank under one of the bunks.

My plan is to put dual fresh water tanks(about 20 gal each) under the booth seats up front, and use a demand pump to supply water.

Secondily, I intend to put a grey water tank where the old fresh water tank is(under the bunk, above floor). I will install a small shower drain pump thingy to pump the shower and bathroom sink back up to this tank.

So my questions are--

How much fresh water do I need onboard? Do I really need dual 20 gal tanks?

Is it absurd to put the grey water tank above floor? How much capacity do I need (25 gal ok)?

How does a demand pump work? Senses water use and starts pump I assume?

I appreciate the help as always.

[uwe]

We carry 50gal fresh, 15 gal black, and 30+or so gal grey capacity.
The grey is an added on tank, not a factory item.
This is enough for 2-3 days dry camping if you're conservative.
40 gal fresh is definitely not overkill, in my opinion. You won't have to fill it, if you don't want it, but it's nice to have if you need it.
Black:
15gal over floor, toilet on top works great.
Grey: 30+gal under floor works very well also. Grey tank on top of floor is not adviseable, need pumps and buffer tank for proper shower function.
Get a flat tank and mount it under the floor, close to the black tank. Makes plumbing easy, and does not require pumps/engineering to work.
The demand pump will come on as soon as you open the tap. It works on a pressure sensor in the output line. Get a pump/accumulator combination, it smoothes out the flow and keeps things quiet.
Try and get all the tanks as close to the axles as possible, and keep them as low as possible for better handling, generally.
If you drop the belly behind the axle, and take a look, you will quickly see if there is room. You can mount it between the frame rails, and between stringers. If it needs to hang low, then just simply fabricate a belly pan piece to go around it. It's not hard to do. Check out the thread on grey tanks.
Good luck!

[Marlboro Mafia]

As always, Uwe are the man!

[uwe]

Try RVpartsoutlet.com for custom tanks. They have very good quality and deliver promptly.
I'll be getting tanks for a 1971 Safari soon, going to look at it next week, drag it home if it's reasonable enough. This one is going to be a full custom, I think, as most of the interior apparently is missing already.
Good Luck with your project!!
And - Happy Easter!