Periodical cleaning of water storage tanks installed on rooftops is an essential process that every house owner has to follow. Water supplied to the tanks has many dissolved salts and impurities that keep depositing on the walls and bottoms of the tanks and build into thick layers if periodical cleaning is not carried out. Dead lizards, rats, birds, insects are often found in the tanks when cleaned. Water storage tanks can be made from bricks, polyethylene, polypropylene, steel or fiberglass. But all of these require periodical cleaning. However, the method used to clean the tanks is often rough and unhygienic, and most often fails to ensure proper cleaning of a tank. Let’s have a look at the right method of water-storage tank cleaning:
This depends on the condition of the water storage tank. It has been seen that top of the concrete or masonry water tanks often have crevices around the tank cover, and these allow dust, insects and reptiles to enter the tanks. Such tanks need cleaning at short intervals of three to six months. Plastic tanks, properly sealed with lids can, however, be cleaned at one-year interval.
Use systematic approach
A common method of getting the water- storage tanks cleaned is to call a plumber who drains out the tank water through one or two taps and then enters the tank to rub its walls and bottom with brushes. He generally uses soap, caustic soda or other chemicals to clean the walls. As most of the tanks have the water outlet an inch or so above the bottom, so some all the water is not drained from the tank. The plumber uses a rug or a cloth to soak the dirty water before cleaning the bottom of the tank.
However, this is not the proper cleaning proces. Cleaning should be got done in a systematic manner. First of all, water stored in the tanks should be drained out completely by using a high- capacity de-watering pump. The process takes a few minutes only. Otherwise, draining out the tank through the taps takes a long time and some water is still left inside the tank.
Next, the tank walls and bottom should be cleaned of all deposits through high pressure and vacuum cleaning. Mechanical scrubbers should be used on the walls, where necessary, to remove the deposits. Any sludge collected at the bottom of the tank should be removed mechanically. No use of chemicals should be made to clean the tank walls.
After the cleaning the tank walls and bottom, the sludge at the bottom and any organic or decayed items in it, it should be given an anti-bacterial spray. This would clear the tank of all micro-organisms and make it bacteria free.
Once the water-storage tank has been cleared of all the physical and chemical deposits, it is preferable to administer ultra violet ray treatment to its inside area. A high-power UV ray lamp is used for this purpose. It is hung inside the tank and the end result is a completly cleaned and disinfected tank.
Precautions during tank cleaning
- Whenever water-storage tank cleaning is undertaken, take care to close the inlet valves on the supply pipe to the tank from your submersible pump as well as direct supply pipe.
- Don’t run the submersible pump during the cleaning process.
- In case water from the tank is discharged on the roof of the house by using de-watering pump, ensure that the drainage and rain water pipes are not clogged. This would avoid flooding of the roof.
- Don’t forget to open the inlet valves after the cleaning process is over.
- Ask the cleaning team to check the floating valve installed in the tank and to seal the tank lid well. Normally the cleaning teams keep extra floating valves and tank lids with them and provide the same at a nominal charge, if required.
- There is every possibility of water not coming out from some of the faucets in your house after the cleaning of the overhead tank. This happens because some deposits from the tank flow through the pipes and get accumulated on the aerators. So remove all aerators, wash and refit them to have that milky flow emitting from the taps and faucets.
The cost of getting your water tank cleaned may vary from city to city. A number of professional companies are in this business now. As these companies send a team of five to seven skilled workers with all the necessary equipment, the charges can be more. Normally these companies charge on per litre basis, with fixed minimum charges. The charges vary from 60 paisa per litre of tank capacity to 80 paisa per litre. Thus, the cleaning of a 2,000-litre tank can cost around Rs 1200.