Per a recent discussion (May 16, 2016 response by Pugtracker
http://www.montanaowners.com/forums/...esh,water,fill) it
is possible to fill the fresh water tank using the on-board water pump. Here is how one member does it:
I hear ya. If keystone would put out a here's how to do it when all you have is a 6 gallon jug of water or a bladder they could be heros.
Pretend you are going to winterize unit
1. Fill portable water source
2. Put hose in or attach to portable water source.
3. Attach to the convenience winterize 3/4 outlet
4. Turn on valves as if you were going to winterize and get a suction.
5. Once you have suction and water is flowing through outside shower hose you are ready to fill.
6.take shower hose attached it to city water fill and fill your water tank by flipping your lever to the fill position.
I have 50 gallon bladder and do this all the time. This of course is done with the modern convenience center.
If you do a "Search" using "water fill" (or such) you should get a number of topics (many with just complaints) and a few solutions.
Personally I use the 12V Harbor Freight water pump method to refill from my 40 Gal. bladder.