Question
How difficult and how expensive would it be to add either a cistern or rain barrels to a pre existing sprinkler system. obviously it depends on multiple variables but I'm wondering if it is feasible and financially worth it because I'm passionate about water conservation and would like to go in this direction.

Answer
Hey Buck, the cost would probably run from $500.00 to $1000.00 depending on how big of a pump and how big of a cistern you would need. For a smaller pump would run from $150.00 to $200.00, where a larger pump could run from $250.00 to $500.00. Same with a cistern from $300.00 to $600.00 depending on size. Keep in mind you would need to figure out how many gallons are being used each time you run your sprinklers. For Instance, lets say you have 8 zones(valves) and each zone uses 15 GPM(gallons per minute) and you run each zone for 20 minutes. This means that each zone is going to need 300 gallons of water (15GPMx20 minutes=300gallons). If you have 8 zones each using 300gallons, then each time the system runs, it will need 2400gallons of storage capacity (8zonesx 300gallons= 2400gallons). The problem might not be in having a big enough cistern, but in are you able to capture this much water in a rain storm, irrigation ditch, river, etc. It is fairly simple to hook your existing system up to a pump and cistern, if you are handy you could do it yourself. You could re-coup your money within a couple of years I would think, depending on how much you get charged for water. Again, my biggest question, would be if you can keep your cistern full by another means besides purchased water. Hopefully I've answered your question, let me know if I can be of anymore help, thanks and have a great day.