We recently have had issues with low yields from our borewells in the building in which I stay. We shifted to our building back in 2011 and the water levels were good then. The builder applied for an OC from BBMP and it was only then we realized that Rain Water Harvesting was carried out in a haphazard manner by the builder. There was only recharge well for the building when the law says there should be a minimum of three for every borewell dug. We have three borewells. Despite having recharge wells, we have had issues with water levels going down in our building. A little bit of caution and adhering to these points will save us a lot of trouble:
(1) Recharge Wells do not necessarily mean an increase in borewell water levels. The flow of water below the ground is uncontrolled and it could recharge any of the borewells in the neighbourhood.
(2) The wells were dug without any geological survey of ground water and with no awareness of recharge points. It is important that people insist on a survey by a geologist of the ground water levels when they buy a new flat. This shall ensure that buildings have their chief source of water- borewells undisturbed at all times.
(3) There was no water storage system in our building. We had this implemented in 2012, which helped us reduce our dependence but our use of borewell till that point of time was so much that it reduced our ground water levels. It is necessary that customers insist that the builder provide a water storage system.
(4) There are 26 brands of Rain Water filter available in the market. 24 of them are used for agricultural purposes. Two are used for residential purposes i.e. Rainy and the pop up filter offered by KSCST. The patent for Rainy has not been obtained. There is also a case against the vendor now since the technology has been copied from a German company without the requisite permission. Use of the pop-up filter shall ensure the maximum storage of water.
(5) It is important to know whether the land on which the building is being constructed was used for residential, commercial or farming purposes. Farmlands require a lot of water, particularly, those which involve cultivation of coconut. Our land was a coconut grove before the land was converted. This explains the depleting water levels.
(5) The sanitation lines and RWH lines should be separate as mixing of these two might lead to contamination of ground water as used water could flow into the recharge pits along with the rain water. Our building has sanitary and recharge pit pipes running parallel to each other with interconnection at some points. This means that the quality of ground water has declined over a period of time.
We have decided to go for a direct borewell injection system, which should hopefully solve the problems. The company, which is executing the work for us had shared the following pieces of information:
(1) Never inject rain water into an active borewell. This could damage the casing and the fissures in the borewell ultimately damaging the acquifiers.
(2) The direct water injection into a borewell should flow drop by drop and not flow with force. If water gushes into the borewell, it could kill the well.
(3) The water needs to be filtered and stored in a sump/ tank before it is let into the borewell. Direct flow of rain water could mean a lot of silt could flow along with the rain water killing the borewell completely.
(4) Storage of water in a tank is a must as no filter has the capability to remove all the silt
(5) The terrace needs to be cleaned thrice a year, one before the monsoon, once during the monsoon and once after the monsoon. This shall ensure that water that is stored or let into the ground is pure and soft.
(6) It is necessary to fix gratings at all the rain water points on the terrace, so that no animal(squirrels, rats) can get into these rain water pipes
(7) Clean the filters once before the monsoon and once after the monsoon.
Rain water is generally softer than ground water or even the Cauvery water supplied by BWSSB. It becomes hard only when it hits the surface so catching the water at the terrace level means that soft clean water is used for day-to-day needs.
The Cauvery water that is supplied to our homes is mixed with borewell and rain water. There are a 1000 borewells near the ground level reservoir of BWSSB on Kankanapura Road. Catching every drop of rain water shall reduce our dependence on Cauvery and reduce the carbon footprint effectively. There is a perception that rainwater is not fit for consumption. This needs to change as rainwater is generally softer and cleaner than groundwater or even the water supplied to our homes by BWSSB.
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