You may notice an increase in your water bill for your splash pad’s initial filling. The average tank size for a splash pad is about 250 gallons, so you shouldn’t notice very much of an increase going forward. How often you use the splash pad and how many hours at a time you let its water features run will influence your monthly water bill. On average, many households see an increase of $20-40 per month when enjoying their splash pad eight hours a day for 30 days. It may fluctuate based on your local utility rates.