Here is the 4-tank water manifold on my h40.5. The problem I had was how to indicate which tanks were still full, which were empty, and which was in use.

H40.5 Fresh Water Tank Manifold

I purchased 4 feet each of red and green ½ ribbon. I placed the two ribbons together and made one row of stitching down the middle of the ribbon. I cut the red-green ribbon sandwich into 10 pieces and sewed the ends together. It took less than 30 minutes to do this and I am not an accomplished seamstress.

When a tank is full, place a ribbon ring over its valve with the green-side turned out. When a tank is empty, turn the ring inside-out and place it on the valve with the red-side out. Leave the ring off entirely for the valve of the tank in use. Now, instant inspection shows which tank is in use and which tanks are full/empty. You could number the rotation order of the tanks so that you dont get stale water in any one tank.

Colored Indicator Valve Rings