Unusually for India , when May is the hottest month generally, Bengaluru sees quite a large amount of rainfall. May, on an average, is the fourth rainiest month of the year. In fact it rains more in May than in June and July even after the monsoon has set in.
With about seven rainy days and about 110 mm of rain, it is best that the city make use of this rainwater. For now, it is not raining enough in the catchments for it to accumulate in the dams of the KRS and the Kabini, the sources of water to the city.
There is a reason why there is no run-off when the pre-monsoon showers come. The soil is dry and in a condition of moisture deficit. Whatever rain falls is quickly absorbed by the soil, not allowing for it to accumulate and become streams. On the other hand, in the city, when it falls on roofs and pavements it still continues to run-off. A small catchment is much more efficient in allowing us to pick up water than a large catchment. Our rooftops are the ideal catchments to pick water as a supplement to our requirements.
Here is how we can harvest the May blessings.
First, keep the roof clean: Applying a coat of white insulating paint not only keeps the roof and the house cooler but also enables it to be cleaned easily using a broom or a swab. May is dusty and the roof tends to accumulate a lot of dust. Remember, the May rainfall however comes in the evening hours and therefore cleaning up the roof can be a dawn activity.
Second, set up a rain barrel: Connect the pipes collecting the roof rainwater and bringing it down to a HDPE tank. Place the tank at a slight elevation and on a firm, stable base so that you can draw rainwater from a tap if you have to. Remove the top cover of the HDPE tank, replace it with a cotton cloth folded three times and tied tightly to it. The cloth will filter the rainwater from dust and debris and allow only clean rain to be collected.
If you do not have space for placing a HDPE tank then connect the rainwater downpipes to the sump which should usually be there in every home. A filter to separate dust would ensure clean water goes into the sump tank
Third, adopt your storm-water drain: There must be one flowing on the roadside in front of your home or apartment. Adopt it. Clean it from garbage and make sure there is no sewage flowing in it. Get a recharge well dug in the stormwater drain or adjacent to it in your plot.
Divert all the storm-water that flows in it during the May thundershower through a filter into the well. This will recharge groundwater, stop flooding and make sure that borewells do not go dry.
Fourth, get a recharge well dug: If your house already has a well the no-brainer is to lead rooftop rainwater through a filter into the well. In case it is a borewell lead the same rooftop rainwater into a small recharge well which you can make next to the borewell. Sometimes borewells can be directly recharged.
Fifthly, adopt a lake: There must be a tank close to your home. Get together with folks, form a Friends of the Lake and start interacting with authorities to make sure that storm-water drains free from garbage are being directed through a wetland into the lake.
This will take time and effort and will not be easy but is simply worth doing. Already, across the city, communities are taking charge of their lakes and fighting battles to save them. Join the group.
A large drought has gripped the nation. Efforts to combat it begins from our homes and neighbourhoods. Rainwater harvesting and demand management is one way of becoming part of the solution. It is May Day for water. Become waterwise.
