Similar to the power system, I’ll have an “internal” water system, as well as a portable water station. The van will have a sink which will require a fresh water tank, as well as a gray water tank. The size of these tanks are TBD.
Some van builds include built in showers. I've decided I don’t want to use up precious space on a built in shower that I might use once or twice a week (at most). In any instance where you’re near a truck stop or gym, you have access to a shower. If I’m back home or at work, I have access to a shower.
The solution to this problem will be a portable water/shower system. Rinse Kit makes both portable rinse/shower stations, as well as a water heating unit that works with the Rinse Kit. Both of these will cost around $550 (total), but requires a lot less maintenance and is dead simple compared to building a water system. These are also portable, and can be taken outside of the van as they’re powered with internal batteries. I’ll look into building a pop-up in-van shower system, if I’m unable to find another shower. I’ll also buy some magnetic tarps to create a private shower in the rear of the van while camping. Van Wife Components sells something like this.
As always, plans may change in the future once the build starts, it will all depend on available space, budget, and other limitations.