How are we going to hold our water?

Depends on the source, I suppose. Up to now, it's been a completely tankless task. But that begins to change with this entry.

We will be installing our fresh water tank and plumbing it to a water pump and water inlet port (see the 21 Dec. '15 entry).

As you may remember from that entry, (or more likely don't remember since I didn't discuss its capabilities in depth), we are using a 4-way Anderson Brass valve. This valve allows one to
1. Fill the tank with city water, under city pressure.
2. Winterize using an  unpressurized source and Annies' water pump.
3. Run the cold line fixtures from the tank with the on board pump.
4. Run the cold line fixtures directly from city water, under city pressure.

Here is a pic of the various valve connection points:

The valve allows  two of the ports to be connected, depending on the function you want.
For example, to run fixtures from the tank, the tank is connected to the pump input:

I wanted to add another function for the times, out in the boonies, when we  might need to refill the tank from an unpressurized water source. (Of course we'd use an external in-line filter for that.)

So, I came up with a modification that should allow use to use the winterization mode to fill the tank.

In winterize mode, the pump's input is connected to the outside water port. If we want to fill the tank that way, we set the valve to winterize mode and set the external 2-way valve to have the pump output feed the tank's upper port via the check-valve (more about the check-valve later...once your eyes are thoroughly glazed).

Otherwise, we keep that 2-way valve set to normal mode.

In city fill mode, the pressurized source directly feeds the lower tank port, and via the check valve, the upper port as well. I want to be able to fill that way because it should be faster than only feeding through the lower port. The pump is turned off when we're filling from a pressurized city source, so its built-in check valve prevents any backflow into the pump.

When we use the tank as our water supply, the 4-way should function normally...with one exception.

If the tank water level falls below the upper port, I suspect there is a chance that the pump would just suck air through that port without my check-valve in place.

OK, so much for theory. Now on to actually installing the ***$$(**@ thing.

The tank has a 41 gallon capacity, and sits 17" high. It will live under the bed, and feed the bath and kitchen sinks, and the H2O heater. The top of the tank is above the level of the exterior fill port.

First I made up a frame to mount the tank.

Upper and lower section being glued. They will also have metal braces.

Mounting the frame and tank to the floor. It's bolted in, and the tank is also glued down with 3m 90.

The tank sit almost directly over the axle. 

I mounted the pump, and started experimenting with plumbing line placement.

Most of the lines are 1/2" PEX. The pump is connected with flex hose in the hope that it will help de-couple noise and vibration.

Detail of the fill port connections:

 And the hook-up at the tank:

The blue lines are the feeds to the eventual fixtures. That probably won't get its own writeup.

The  line at the lower right of the tank will go to the drain outlet (and valve). The drain will exit through the floor near the rear door.

The clear hose exiting the tank at the upper left is the vent hose. It vents at the external fill port.

In the next few days, I'll tie the lines down, temporarily plug up the ends and start testing for leaks.