Soon, Mumbai's buildings will have rainwater harvesting structures

To reduce the dependence on water supply from dams and tap rainwater that otherwise goes waste, it will soon be mandatory for buildings coming up in urban areas to establish rainwater harvesting (RWH) structures.

According to the draft Maharashtra Groundwater (Development and Management) Rules, 2018, urban local bodies and panchayati raj institutions shall approve the building plan of an area of 100 square meters or more if appropriate rain water harvesting structures are provided in it.

Suggestions and objections have been sought from people on these rules, which will enable the implementation of the Maharashtra Groundwater (Development and Management) Act, 2009, once they are finalised by the state government.

In recharge-worthy areas, these RWH structures must use 50% of the water to recharge the aquifer. In non-recharge worthy areas, where the water table may already be high or the geology may be non-conducive for water harvesting, underground storage tanks should be constructed to use this water. The rules stipulate that the urban local bodies and panchayati raj institutions shall provide permanent water connections and occupancy certificates (OC) to builder owners only after receiving a satisfactory proof of compliance.

"It will be compulsory for all buildings of 100 square meters or more in the rechargeable zone to have RWH structures," said Shekhar Gaikwad, director, Groundwater Surveys and Development Agency (GSDA). "This will be done on a scientific basis. Ground water experts will map the urban areas in the state and identify zones that are useful for water recharge... there are some zones that may not be conducive for RWH for reasons like basalt rock or geology that does not allow water to percolate and the need for water harvesting," he explained.

He added that while some municipal bodies had made it mandatory for new buildings to have rainwater harvesting, in the absence of these rules, there were instances of this water being discharged into the drainage systems.

Gaikwad said while the around 42,000 villages were mapped and would be notified as rechargeable or non-rechargable zones, they would have to survey the urban and municipal areas in Maharashtra to determine these zones, which would take time. Maharashtra has 1,531 watershed zones.

The State Groundwater Authority shall direct the GSDA to provide maps demarcating recharge-worthy areas and issue directives to the concerned local bodies to make construction of RWH structures mandatory. Moreover, if the occupants, developers or builders of the society or premises, fail to construct the structures within six months from issue of notice, the urban local body shall construct the rainwater harvesting structures for such buildings and recover 1.25 times the cost of its construction.

The rules empower the groundwater authority to notify polluting industries and direct its closure to the concerned state government departments until the unit implements necessary measures and restores the quality of groundwater to potable standards prescribed by the Bureau of Indian Standards.

Apart from Maharashtra's peculiar physiographic configuration, the presence of basalt and metamorphic rocks in around 91% of the state limits the development of ground water due to the adverse hydro-geographical configuration. Around a third of the state's geographical area is a rain-shadow region with scanty rainfall.