Can you get coupons for the days you don't use it? I think that this is for watering the lawn though, I don't know if anyone would say anything about filling a pool. That is not something that can be prolonged, it needs to get filled, and balanced ASAP.

Worst case scenario, buy it from a water truck. You may be able to get access to a hydrant and some hose if you talk to the fire department or the public works office. They have a meter that can go on the hydrant port. I did it before and I filled my pool in two hours, 8000 gallons.