brackishwasher

I want to buy a 15-25 gallon tank with 12v pump for my house. I already have a adequate pressure washer. I need one to use 2 or 3 times a year and will reach the top of the sides of the house ( about 35 ft) I will spend 2-400 as needed. Any advice would be greatly appreciated. The one's I find online seem more for use with lawn chemicals, so I worry about their reach. Also, any advice (while we're at it) on an all-in-one primer/paint to use on the picket fence? Some parts were painted without primer and are flaking badly after 2 yrs, and the well-painted parts need touching up (overzealous with the pressure washer)