We have two systems to share:
Old:
We used a mil spec Scepter can (same as the scepter NATO gas cans but blue and with a pouring spout lid) to store and transport. It went next to a jerry Can in a holder on the rear bumper.
To fill it, we had an RV water pump wired to a switch with an automatic pressure shutoff, and we brought 30’ of hose. We could pull from any stream or creek into a waterproof bag. In our case we used the bag from the Katadyn base camp, but the filters are garbage so I’d suggest using an MSR Dromedary bag instead. The bag is filled with water and then hung from the roof rack. The cap has a tube that was about 5’ long, and we mounted a sawyer mini to the end. That way, we had a gravity filtration system that would ensure clean water only entered the jerry can.
We also have a water heater mounted in a pelican case, which also hooks up to our pump. This pump pressurized the system straight from a bucket so we had hot showers as needed. I’ve written in the importance of a shower elsewhere for safety reasons so I won’t repeat that here; some see it as a glam ping accessory but for us, for our trips it’s a must have safety item.
New system:
Our new system is designed, and many products are purchased, but we have not installed it yet as I’m not there with this build. Our goal was to make it truly ‘on board’ where as our old system was much more modular with various separate components that all took up valuable cargo space.
Onboard water tank (10 gallons) and pump system for water storage. Filtration system right before the tap, which is where we get all potable water from. Fill cap on the side with a lock, and a manifold that is plumbed so the pump can either pull water from an outside source, or pressurize the whole system for running water. Heat exchanger plumbed into the coolant system of the truck, which reduces the number of items we need to bring.
And (this is totally a luxury, not a necessity) an onboard soda stream for zesty drinks on demand. I know, this sounds ridiculous, but neither of us drink alcohol anymore for health reasons, nor do we really like sugary Drinks like soda and such. Our ‘treat’ drink is zesty water with a splash of lemon, so where some bring coolers full of beer, we just drink Zesty in camp.
I imagine a few will tease us about this, but that is okay; our skin is very thick. Because we are well hydrated thanks to our onboard zesty machine ;)