The cost to fill a swimming pool with water depends on the size of the swimming pool.
If you're using city water from your hose it typically takes around $10.00 to $30.00 in water to fill up the average home size swimming pool.
The large the swimming pool the more it costs in water to fill up the swimming pool.
I have a 5,000 gallon swimming pool and at most it adds $10.00 to my water bill because the cost of my water is around $2.00 per 1,000 gallons of water.
That's pretty reasonable to fill the swimming pool up with my garden hose.