Rain Water Harvesting in UDCPR 2020

Apr 08, 2024

UDCPR 2020 Chapter 13 is all about the Special Provisions for Certain Buildings as per mentioned in the UDCPR

This is Applicable to all Planning Authorities and Regional Plan Areas except Municipal Corporation of Greater Mumbai, Other Planning Authorities/Special Planning Authorities/ Development Authorities within the limit of Municipal Corporation of Greater Mumbai, MIDC, NAINA, Jawaharlal Nehru Port Trust, Hill Station Municipal Councils, Eco-sensitive/Eco-fragile region notified by MoEF & CC and Lonavala Municipal Council, in Maharashtra.

Rule No. 13.3 Rain Water Harvesting

The provision for Rain Water Harvesting shall be made as under :-

a) All the layout open spaces/amenity spaces of housing societies and new constructions/reconstruction/additions on plots having an area not less than 500 sq.m. shall have one or more Rain rainwater harvesting structures having a minimum total capacity as detailed in Schedule.

Provided that the Authority may approve the Rain Water Harvesting structures of specifications different from those in Schedule, subject to the minimum capacity of Rain Water Harvesting being ensured in each case.

b) The owner/society of every building mentioned in the (a) above shall ensure that the Rain Water Harvesting System is maintained in good condition for storage of water for non-potable purposes or recharge of groundwater at all times.

c) The Authority may impose a levy of not exceeding Rs.1000/- per annum for every 100 sq.m. of built-up area for the failure of the owner of any building mentioned in the (a) above to provide or to maintain Rain Water Harvesting structures as required under these regulations. Failure to provide a Rain Water Harvesting System shall deemed to be a breach of the conditions on which the development permission has been granted.

Schedule

Rainwater harvesting in a building site includes storage or recharging the groundwater by rainwater falling on the terrace or any paved or unpaved surface within the building site. The following systems may be adopted for harvesting the rainwater drawn from a terrace and the paved surface.

i) Open well of a minimum of 1.0 m. diameter and 6.0 m. in depth into which rain water may be channeled and allowed to filter for removing silt and floating material. The well shall be provided with ventilating covers. The water from the open well may be used for non-potable domestic purposes such as washing, flushing and for watering the garden etc.

ii) Rain Water Harvesting for recharge of ground water may be done through a bore-well around which a pit of 1.0 m. width may be excavated up to a depth of at least 3.0 m. and refilled with stone aggregate and sand. The filtered rainwater may be channeled to the refilled pit for recharging the bore well.

iii) An impressive surface/underground storage tank of required capacity may be constructed in the setback or other open spaces and the rainwater may be channeled to the storage tank. The storage tank shall always be provided with ventilating covers. It shall have draw-off taps suitably placed so that rainwater may be drawn off for domestic, washing, gardening and such other purposes. The storage tank shall be provided with an overflow.

iv) The surplus rainwater, after storage, may be recharged into the ground through percolation pit trenches or a combination of pits and trenches. Depending on the geomorphological and topographical conditions, the pits may be of a size of 1.20 m. width X 1.20 m. length X 2.0 m. to 2.50 m. depth. The trenches can be of 0.60 m. width X 2.0 to 6.0 m. length X 1.50 to 2.0 m. depth. Terrace water shall be channeled to pits or trenches. Such pits or trenches shall be backfilled with filter media comprising the following materials :-

a) 40 mm stone aggregate as the bottom layer up to 50% of the depth.

b) 20 mm stone aggregate as the lower middle layer up to 20% of the depth.

c) Coarse sand as upper middle layer upto 20% of the depth.

d) A thin layer of fine sand as a top layer.

e) Top 10% of the pits/trenches will be empty and a splash is to be provided in this portion in such a way that rooftop water falls on the splash pad.

f) Brick masonry wall is to be constructed on the exposed surface of pits/trenches and the cement mortar plastered. The depth of the wall below ground shall be such that the wall prevents lose soil from entering into pits/trenches. The projection of the wall above ground shall at least be 15 cm.

g) Perforated concrete slabs shall be provided on the pits/trenches.

h) If the open space surrounding the building is not paved, the top layer up to a sufficient depth shall be removed and refilled with coarse sand to allow percolation of rainwater into the ground.

v) The terrace shall be connected to the open well/bore-well/storage tank/recharge pit/trench by means of HDPE / PVC pipes through filter media. A valve system shall be provided to enable the first washing from the roof or terrace catchment, as they would contain undesirable dirt. The mouth of all pipes and openings shall be covered with mosquito (insect) proof wire net. For the efficient discharge of rainwater, there shall be at least two rainwater pipes of 100 mm. dia. for a roof area of 100 sq.m.

vi) Rain Water Harvesting structures shall be sited so as not to endanger the stability of the building or earthwork. The structure shall be designed such that no dampness is caused in any part of the walls or foundation of the building or those of an adjacent building.

vii) The water so collected/recharged shall as far as possible be used for non-drinking and non-cooking purposes. Provided that when the rainwater in exceptional circumstances is utilized for drinking and/or cooking purposes, it shall be ensured that proper filter arrangement and a separate outlet for bypassing the first rainwater has been provided.

Provided further that, will be ensured that for such use, proper disinfectants and the water purification arrangements have been made.

The structures constructed under this provision shall not be counted toward FSI computation.