After boondocking at Quartzsite in January, and fellow RVers helping out, the method used was a 45 gallon bladder, http://www.campingworld.com/shopping...45-gallon/1605
, and a water pump from Harbor Freight, http://www.harborfreight.com/12-volt...ump-94639.html
, and whatever method suits your situation for connecting the 12 volt pump to your 12 volt power point, was the best method I found. I purchased a plug to fit the trailer receptacle on the pickup, and wired the pump to the plug, through a switch. As long as you have a good source for water, this works great.