Try the white-cloth test
Gritty means minerals or silt, slimy flakes mean biofilm, rubbery bits mean a failing washer.
KaamGenieBlack Sediment in Your Tank
Those dark specks at your tap aren’t all the same problem.
First, test it
Cause 1
Manganese from borewell
Borewell minerals oxidise into fine black grit once they hit air in an open overhead tank.
Cause 2
Biofilm — a hygiene risk
Dark slimy build-up on neglected walls breaks off in flakes and can harbour bacteria. It must be scrubbed off.
The fix
Drain, scrub, vacuum
A rinse won’t do it. The settled black layer has to be physically removed, then disinfected.
Don’t forget
Clean the sump too
Sediment in the sump gets pumped straight up into the overhead tank — clean both or it half returns.
Book now
Tank cleaning from ₹699
Trained crew diagnose the cause, drain, scrub and disinfect — same-day where possible across Delhi NCR.