Water delivery costs vary depending on the current rates in your area. Most pools hold 15,000-30,000 gallons of water and delivery services charge by the gallon. The national average for water is around $2.00 per 1,000 gallons of water. But delivered water is much more expensive when you factor in delivery costs, and the local taxes and fees that apply. Expect to pay at least $1,200-$1,500 to have a 15,000 gallon pool filled by delivery. Remember, most delivery trucks do not hold 15,000 gallons, so multiple trucks or deliveries are necessary. The water is generally cheap, but the delivery is not.