Hi i would suggest using ...

Published April 28, 2020 02:18 by Steve Williams, The Water Guy

i would suggest using rainwater tanks for the following reasons:

Run off contamination from roofs and non point source run off.
There could also be a fair amount of treatment from fish wastes if heavily populated.
Evaporation
Security of the water from contamination of unexpected events

Solutions:

If you design a system using the first flush technology collecting from only from the roof water should be of potable quality only needing filtration by UV and charcoal to insure quality. See attachment.

As for evaporation up to 73% of water can be lost through evaporation in a year. A study found with Lake Lanier near Atlanta, Ga USA. Rainwater tanks lose very little water from evaporation. US Department of Commerce Technical Paper NO. 37, M. A. Kohler, T. J. Nordenson and D. R. Baker Hydrological Service Division, 1959

Water run of from surrounding areas could also effect quality and accidents can happen.

If interested in pursuing a more traditional form of rainwater harvesting let me know. Not sure of the cost comparison, but maintenance would be very simple and less costly.