Is 50 gallons of fresh water enough for boondocking?

Yes, unless your a heavy drinker...

Depends on how many people and how long and how conservative you want to be.

Fresh water can be replenished with Jerry cans filled “in town.” Toilets can be flushed with lake and stream water. When black and grey tanks are full you are required to move the RV to a dump site. So, IMO, waste tank capacity is more important when boondocking.

Two of us use about 7 gallons per day and quick shower every other day. Black water is probably about two gallons a day and I have a hard time keeping track of the gray water as it seems to just disappear. :)

I have a 60 gallon bladder and four jugs so I'll hit an RV park tomorrow to pick up 80 gallons

For the three of us that would be a week max with just a sponge bath or the quickest of showers.
A little longer if in a campground with facilities but no hookups.

asking how long 50 gallons of water will last is a iffy question. there are too many things to consider to give an accurate answer. we had a 40 gallon tank and four in the family and we did fine because we didn't take showers every night. the kids took baths and wife sponge bathed. we last many days. cooking takes a little bit of water but dishes didn't since we used paper plates and cups

To me, the grey and black tanks are more important as to how long you can boondock. We always ended with fresh water left but the other two tanks were full. You can easily bring in more water via jugs.

We had 105 fresh water; 65 grey and 45 black. Two of us could boondock 12-14 days and still have fresh water left. We were very conservative with use. We didn't dump grey water on the ground.

We used the tank for everything, including drinking. When it was time to dump we were ready to move on to new surroundings anyway so no big deal.

Family of 4 here. We managed a week out of 45 gallons and a 30 gallon gray. As said above, we brought in more water with jugs and used it for outdoor washing of hands, dishes, etc. If it didn't HAVE to be done in the trailer, we didn't. We were VERY good at managing water and could have never done this in our first year of travel.

Realistically, 45 fresh and 30 gray is barely okay for 2-3 days. It can be burned through in one day VERY easily.

In our new rig, we have 70 fresh and 60 gray, and can easily put jugs in the basement. I imagine we can squeeze 2 weeks out of it, but more comfortably do a 4-5 day stay (which is more typical of our use anyway).

Yes.

Had a single friend once who boondocked for over a year on three gallons per day. You can do the math. She was fanatical about getting usage down as low as possible, using one of those gallons to do dishes and then flush toilet. One went to cook and drink. The third went for sponge bath then flush toilet. YMMV.