How long will a slow sand filter “run” before it needs “repair”?
This is a good question. This blog has 8 years of posts documenting the slow sand filters running here. I can say with certainty that the longest running filter here (filter 1) is still fully functional after 8 years of continuous running (with the exception of several weeks each winter when all the filters freeze up and stop running). In filter 1, the sand has not been changed and the filter has not been wet-harrowed; and no sand has been removed or added. Recirculation is used in the summer when little or no rainfall occurs.
The other filters running here have been in continuous service for various lengths of time. Anywhere from 5 years to 8 years. All filters, with the exception of the 5 gallon filters, and the smaller 1/2 gallon filter, are still fully functional and currently in service. The 5 gallon filters were not successful, and we have stopped working with them. The smaller 1/2 gallon filter was never fully tested thoroughly enough to show any success.
I had installed 3 stage underground cement ring and stages base rain water harvesting system in which we use silica quarts gravels and sand as 3 different stages to filter rain water can u help how i back wash entire system with out manually cleaning it i mean by using pump in system out let and system gets clean by removing dirts from drain pipe can u provide me some drawing of such system
I am very sorry, but the filters we have built here do not use backwashing, they use a process called wet harrowing which involves gently agitating the surface of the sand in the filter. I cannot offer any technical advice on backwashing a sand filter. Try searching on line for backwashing a sand filter.
Slow and filtering sand helps to clean water which can be drink. Saving rain water into into tank which can be used for harvesting.
That’s great that your filters have lasted so long. Have you noticed any leaching of nutrients from them into the treated water?