I had a borewell dug in year 2012 and it was all good till this year and I had automatic controller for borewell pump that pumped around 5000 litres daily. During overhead tank cleaning, there used to be red/brown silt in the tank that was not noticed in the tap water.
From June this year, water started coming muddy(brownish) for around 2-3 minutes after the motor ran for about 5 minutes. Post that mud will quickly clear out and will become largely clear in next few minutes. For last two weeks, water has started coming full black in the same pattern, i.e. After about 5 minutes of running the motor, black water comes for 2-3 minutes and quickly it will become clear in the next few minutes. So water can not be let in to overhead tank for around 8-10 minutes till the mud is cleared after starting the motor, else it makes entire overhead tank water noticeably muddy.
Camera test of the borewell was done this week and we observed that there is a new water source @125 feet depth that seems to bring this mud. This source was not there when camera test was done March last year when there was water scarcity in Bangalore. There is no water leakage in the borewell till that depth of 125 feet and I checked this during the rainy day recently. So this water is not a seepage from ground like sewage or storm water drain.
I need opinion from experts who have knowledge of this on what is really causing this?. Some possible reasons
1. I hear from neighbors that their borewells (low depth) that were dry till early this year have started yielding water recently. So due to Covid lockdowns causing less water usage in Bangalore, possibly ground water level has increased leading to new water source in the borewell.
2. Why is water heavily soiled/muddy only for 2-3 minutes only and after that it is not noticeable
3. How did the color change from brown to black in a matter of two months. What could be happening
4. When I tested water in a lab, report has come as water turbidity is high, E-coli is absent, but Total Coliform bacteria is present. This was not the case before this new water source @125 feet depth started.
I have attached some pictures of water collected during the 2-3 minutes of muddy water flow. Could you pls respond on safety of using this water(post 10 minutes of letting out) for non-drinking purpose. i.e for bathroom, washing purposes.
Thank you,
Selva