We do come with about 200 gallons of water in the power wash tank. Although we do utilize homeowner water thereafter for the small amount of water needed to finish the house wash. We can assure you that the water used to wash your home will be pennies on the dollar in cost for you. We use only appx. 330 gallons total for a standard house wash. Johnston County charges $3.90 for every 1,000 gallons of water used. Which brings a standard sized home house wash to approximately only $0.90-$1.20. Power washing in Wake County NC varies by a cent or two, as pricing of water is similar to JC.