My property has an old cistern system for irrigation water to come in and then goes through 4 buried concrete tanks, with gravel and or sand then is stored in a 5th tank for use in the house. The house has been switched to municipal water long ago but it need to be filtered to be usable from all the standard nasty's in the water supply.
I want to put the old system back into use and add 1000 gal of storage and purification. Does anyone have solid information on, what is the optimum sand, gravel filter set up? Any good alternatives or additions? I was thinking about crushed glass for part of it, I know it works well as an alternative to sand as a growing medium for hydroponics, here it is much less expensive than gravel. What is the optimum size and layering to actually get clean water at the end. Was going to go with basic round concrete tanks for the addition as the fiberglass ones are so expensive and I'm not any more confident of their potability than concrete.
Also I was reading an article where the same water after going through an RO system had coliform bacteria in it that it didn't before hand, which seems impossible but??
My plan is to clean it as much as possible then still put it through an activated carbon, RO system, but hoping to have the water fairly clean before it gets to there.