It is called a coping mechanism for infrequent supply of municipal water. The sump – an underground water tank – is ubiquitous in the city. Perhaps it is the first thing built along with a shed for the watchman in every new site in Bengaluru. Since water is not supplied by the city for construction purpose, the sump is built to buy and store water from tankers. This aids the building when it is being built and later it becomes connected to the city mains. The water which comes twice or thrice a week gets stored here and is pumped into overhead tanks for reticulation during the rest of the week.
A cleaning service has now emerged for the sump as well as the overhead tank. After first emptying the sump, a pressure jet pump is used to clean it of silt, dirt and algae. A potassium permanganate solution is then used to disinfect the tanks.
Attention is also paid to clean the sump cover too which can collect a lot of dirt. Connecting pipes, foot valves, floating ball valves are also cleaned.
The beginning of the monsoon is a time when water supply is more reliable. It is also a time to clean up and repair all water storage and pumping devices.
Checklist
Check the sump and overhead tank for leaks. Observe and mark the level at night and observe the level early morning. A dip in level will indicate a leak. Get the leak repaired.
Check for silt deposit and algal growth. This can choke pipelines and solar water heaters. Get silt and algae removed.
Check the ball valve in both the sump tank and overhead tank. A bad float valve can cause unnecessary overflows. This also applies to automatic water level controllers which need to be fixed if not working.
Overhead tanks, especially of the HDPE variety, seem to lose their lids easily. This allows for contamination of water. Get this checked before the monsoon.
Get the sump and OHT disinfected. Make sure the covers are tight and no vectors such as mosquitoes or cockroaches can get in.
Check for residual chlorine in waters supplied by the utility. If it is less than 2 ppm it is a matter of concern and should be reported to the authorities.
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