We enjoy camping on federal lands, especially in the desert, where boondocking is the norm. Some CGs do not have drinking water or dump stations. We think our longest boondock in one site was 5 nights.
The 16' Bambi has a much smaller freshwater and waste water tank (black and gray combined) than the big guys have, so we really have to conserve water.
We usually carry a jerry can or two of water and a big funnel for dry-campground refills.
I don't know how much water we consume per day, but we have developed the following strategies:
1. Use public restrooms if available, at least during the day.
2. Pack lots of beer to save on your drinking water.
3. We don't use disposable dishes when we are set up, but we carry a pack of those Lysol or clorox wipes, and wipe the dishes with them for a pre-rinse cycle. Then we have a brush for washing/scrubbing, so you only need soapy water in a small dish or a cup to wash everything. If outside weather permits, rinse dishes in a plastic tub outside, and dump it where feasible.
4. Less frequent showers-- hey, we're camping! In the Canadian Rockies, you can also shower at one of the wonderful hot springs. But with the Bambi wet bath, we put one plastic wash tub on the toilet seat and stand in the second one, so little water gets wasted. Agree: turn on the hot water first. Hose down, turn off the water, soap up, grab a cup (previously) for rinsing down with the saved water, then do a final hose-down from the shower. This soapy water may have a second use (like Jeanne goes first, then Len takes a sponge bath), but dump it outside.
5. We have tried a no-flush toilet system. It works well from a water-saving perspective, but not so good on the convenience scale. We bought some sturdy garbage bags large enough to fit in the (dry) toilet bowl while covering the rim. We put some peat moss in it (kept handy in a big zip-lock bag.) After each use, sprinkle on a little more peat moss. When your sensitivities say it's full, close the bag and discretely place it in the campground dumpster.
6. Use baby-wipes and hand-sanitizer for routine hand-washing.
Also, we just bought one of the blue portable waste tanks for waste tank emergencies. Which we did have, once.