We do not have water at our shop. I have an idea. I want to get a 500 gal water tank and put it on one of our trailers. How much does 500 gal of water weigh? My idea is to use this tank at the yard and hook a pressure washer up to it for washing trucks and equipement. What kind of pump would I need for this? Would I just be able to use gravity to feed the water into the pressure washer? I would also like to use this as a mobile water tank for watering our Landscape Installs. Does anyone have a set up like this? Any ideas?