This post will find some interest to not only someone building a Flat Bed but also those with a slide-in camper. Grey water storage is a popular discussion topic.
A primary objective of the build was to be able to carry additional fresh water for extended off grid excursions and free up the back seat of the water jugs I used to carry that extra water. In addition, I wanted to incorporate a built-in grey water storage tank. The left front storage box looks like the rest of the storage boxes but in reality, behind the door is a 10 gallon grey water tank and directly under the factory fresh water tank (and in the frame of the flat bed) is an additional 20 gallon fresh water tank. I detailed those items in an earlier post.
Having installed those items, I needed to utilize the in cabinet water pump to bring the exterior water into the camper and to remove the grey water from the sink and into the grey water storage tank.
The next two photos show the holes that were drilled through the floor of the camper and the two hoses used to accomplish the task. These photos were taken prior to filling the voids with spray foam to keep critters, bugs and water out of the camper. Two different diverter valves were deployed to plumb in the additional water lines. The actual valves used and links to where you can find them are included later in this post. I have included the links because it took a bit of time to figure out what would work and then to source the parts. If I think of it next time I am out, I will take photos of the valves plumbed in place and add them to this post.
Inside the hot water heater storage compartment in the flat bed Hawk is a bit of extra room to accomplish this task. You will notice the washer and bolt head that holds the camper to the flat bed in this corner of the camper (left front). It took a bit of planning to place the reinforced backer plate (for the bolt) in the flat bed in a location that would be out of the way of the plumbing and then coordinating the bolt placement at install with the folks at the factory.
This photo shows the fresh water diverter valve. It is the same as the equipment being used in the factory plumbing system. It is a SeaTech 3 Way Selector Valve, Type 38-1/2CTS x 1/2CTS x 1/2CTS valve. It is PN 3538-10 and can be found here:
https://www.freshwatersystems.com/p-1731-seatech-3-way-selector-valve-type-38-12-cts-x-12-cts-x-12-cts.aspx This particular valve allows for one or the other of the fresh water tanks to be selected.
The grey water diverter valve was sourced from a marine supply source. It works in the same manner as the fresh water valve so that I can direct the flow of water from the sink to either the standard side discharge or into the grey water tank. It is a Bosworth Sea-lect Diverter Valve. It carries a manufacturer's part number of: S#94AB-3/4CPH. And it can be purchased here:
https://www.westmarine.com/buy/bosworth--sea-lect-diverter-valves--P011_332_003_524?pCode=399313