Section 5A in The Chennai Metropolitan Area Groundwater (Regulation) Rules, 1988
5A. [ Implementation of rain water harvesting measures. [Rule 5-A was inserted by G O. Ms. No. 68. Municipal Administration and Water Supply (Metro Water) Department, dated 21st November, 2002.]
(1)Every building owned or maintained by the Government or a company or other institution owned or controlled by the Government, shall within one year from the 21st day of November, 2002,-(a)provide rooftop rain water harvesting structure wherever a storage tank or an open well or a bore well is available in the building irrespective of the nature of sub-soil conditions;(b)surface run-off water from the open spaces around the buildings, parks and playgrounds shall be harvested using appropriate recharge structures based in the nature of the sub-soil conditions.(i)Roof-top rain water harvesting - Direct collection. - Rain water from the roof of the buildings such as tiled/ sloped terrace building and flat/ RCC (Reinforced concrete cement) roof shall be collected using appropriate size of gutters or PVC (Poly vinyl chloride) pipes and stored either in a collection tank or storage tank of appropriate size placed over the ground or underground through a filter unit. A filter chamber of appropriate size shall be provided to filter the dust particles usually present in the roof-tops of the buildings. Suitable filter material such as well-burnt broken bricks or coarse sand or small sized pebbles or blue metal gravels (baby chips) shall be used in the filter chamber. The surplus water-available after filling the storage tank/ sump shall be diverted to the nearby open well or bore well or recharge pits. Proper disinfection shall be made while storing the water for long use.Recharging the open well/ bore well. - The rain water collected from the roof tops of both tiled/ sloped roof and flat/ RCC (Reinforced concrete cement) roofs using gutters or PVC (Poly vinyl chloride) pipes shall be diverted to the open well or bore well through a filter chamber of appropriate size. Regular disinfection methods are to be practised while harvesting rain water in open wells.(ii)Harvesting surface run-off water. - Apart from the roof-top rain water harvesting, the rain water available in the open spaces around the buildings and in places/ buildings where a sump or open well or bore well is not available the rain water shall be harvested and recharged into the ground using appropriate recharge structures based on the nature of the sub-soil conditions as mentioned below:(a)Sandy sub-soil areas. - In places where the sub-soil formation is sandy in nature the rate of percolation of rain water will be more and therefore provision of shallow recharge structures such as percolation/ recharge pits, recharge trenches or shallow recharge wells are considered to be suitable for rain water harvesting.(i)Percolation/ recharge pits shall be provided around the buildings with minimum size of 1 metre x 1 metre x 1 metre and filled with permeable medium such as broken bricks or pebbles or coarse sand, etc. The number of these pits shall vary based on the extent of the area of water collection. On an average one unit is required for an area of 250 square feet. These structures are suitable for individual houses in general.(ii)Recharge trenches (Longitudinal in shape) similar to the percolation/ recharge pits are suitable for apartment/ commercial complexes, where the availability of rain water is more. Two or three of these structures shall be provided on the basis of the extent of the building.(iii)Shallow recharge wells are similar to the common open wells except in size and depth. Normally, for an individual house with 1000 square feet area, a recharge well with 1.0 metre dia and 3.0 metre dia depth is required. For apartments/ commercial complexes two or three recharge wells are required based on the extent of the building. Either brick wall or RCC (Reinforced concrete cement) concrete rings shall be used for construction. The top of the recharge well should be covered with RCC (Reinforced concrete cement) slab. Recharge wells are to be desilted once in a year or two for its effective recharge. Rain water collected from the roof tops of buildings and open surfaces shall be diverted to these recharge structures through PVC (Poly vinyl chloride) pipe line or by providing channels on the ground. These structures shall be maintained properly for effective recharge.(b)Clay sub-soil areas. - In places where the sub-soil formation is clay in nature the rate of percolation of rain water will be very slow and therefore provision of percolation/ recharge pit with bore, recharge trench with bore or deep recharge well are considered to be suitable for rain water harvesting.(i)Percolation/ recharge pit with bore. - It is similar to the one mentioned in sandy sub-soil formation except a bore hole at the bottom of the percolation pit which is also filled with the same permeable materials. A minimum size of 4= inch diametre and 15 feet depth is normally required for one pit. However, if sand formation is available below the top clay layer, the bore has to be drilled preferably up to the sand formation. The number of these pits shall vary based on the extent of the area of water collection. On an average one unit is required for an area of 250 square feet. These structures are suitable for individual houses in general.(ii)Recharge Trench with Bore. - These are similar to the recharge pits but are longitudinal in shape and bore holes shall be provided at the bottom for every 10-15 feet of the trench. The trench and bore hole shall be filled with the same permeable materials such as broken bricks or pebbles or coarse sand, etc. These structures are suitable for apartments/ commercial complexes where the availability of rain water is more.(iii)Deep/ large recharge wells. - These are similar to the common open wells except in size and depth and are considered to be suitable for apartment/ commercial complexes. In general, a recharge well with 1.5 metre dia and 5.0 metre depth is required for a small apartment. Either brick wall or RCC (Reinforced concrete cement) concrete rings shall be used for construction. The top of the recharge well should be covered with RCC (Reinforced concrete cement) slab. The recharge well shall be de-silted once in a year or two for effective recharge. Rain water collected from the rooftops of the buildings and open surfaces shall be diverted to these recharge structures through PVC (Poly vinyl chloride) pipe line or by providing channels on the ground. These structures should be maintained properly for effective recharge.(c)Hard rock areas (Weathered). - In hard rock areas also, the rate of percolation of rain water will be slow. Therefore, in order to collect and recharge the rain water it would be preferable to construct recharge wells of appropriate size.Percolation pit with deep bore holes up to a depth of 50-100 feet shall be provided. In this case, the bore hole is to be constructed with slotted pipe for effective recharge. In general, construction of separate recharge structures shall be provided in the absence of existing infrastructure such as storage tank/ sump, open well or bore well in order to reduce the cost involved.(2)Every person who constructs a building, whether, for residential or non-residential purpose, shall on or after the 21st day of November, 2002,-(a)provide roof top rain water harvesting structure wherever a storage tank or an open well or a bore well is available in the building irrespective of the nature of sub-soil conditions;(b)surface run-off water from the open spaces around the buildings, parks and playgrounds shall be harvested using appropriate recharge structures based on the nature of the sub-soil conditions.(i)Roof-top rain water harvesting. - Direct collection. - Rain water from the roof of the buildings such as tiled/ sloped terrace building and fiat/ RCC (Reinforced concrete cement) roof shall be collected using appropriate size of gutters or PVC (Poly vinyl chloride) pipes and stored either in a collection tank or storage tank of appropriate size placed over the ground or underground through a filter unit. A filter chamber of appropriate size shall be provided to filter the dust particles usually present in the roof-tops of the buildings. Suitable filter material such as well burnt broken bricks or coarse sand or small sized pebbles or blue metal gravels (baby chips) shall be used in the filter chamber. The surplus water available after filling the storage tank/ sump shall be diverted to the nearby open well or bore well or-recharge pits. Proper disinfection shall be made while storing the water for long use.Recharging the open well/ bore well. - The rain water collected from the roof tops of both tiled/ sloped roof and flat/ RCC (Reinforced concrete cement) roofs using gutters or PVC (Poly vinyl chloride) pipes shall be diverted to the open well or bore well through a filter chamber of appropriate size. Regular disinfection methods are to be practised while harvesting rain water in open wells.(ii)Harvesting Surface run-off water. - Apart from the roof-top rain water harvesting, the rain water available in the open spaces around the buildings and in places/ buildings where a sump or open well or bore well is not available the rain water shall be harvested and recharged into the ground using appropriate recharge structure based on the nature of the sub-soil conditions as mentioned below:(a)Sandy sub-soil area. - In places where the sub-soil formation is sandy in nature the fate of percolation of rain water will be more and therefore provision of shallow recharge structmes such as percolation/ recharge pits, recharge trenches or shallow recharge wells are considered to be suitable for rain water harvesting.(i)Percolation/ recharge pits shall be provided around the buildings with minimum size of 1 metre x 1 metre x 1 metre and filled with permeable medium such as broken bricks or pebbles or coarse sand, etc. The number of these pits shall vary based on the extent of the area of water collection. On an average one unit is required for an area of 250 square feet. These structures are suitable for individual houses in general.(ii)Recharge trenches (longitudinal in shape) similar to the percolation/ recharge pits are suitable for apartment/ commercial complexes, where the availability of rain water is more. Two or three of these structures shall be provided on the basis of the extent of the building.(iii)Shallow recharge wells are similar to the common open wells except in size and depth. Normally, for an individual house with 1000 square feet area, a recharge well with 1.0 metre dia and 3.0 metre dia depth is required. For apartments/ commercial complexes two or three recharge wells are required based on the extent of the building. Either brick wall or RCC (Reinforced concrete cement) concrete rings shall be used for construction The top of the recharge well should be covered with RCC (Reinforced concrete cement) slab. Recharge wells are to be de-silted once in a year or two for its effective recharge. Rain water collected from the rooftops of buildings and open surfaces shall be diverted to these recharge structures through PVC (Poly vinyl chloride) pipe line or by providing channels on the ground,. These structures shall be maintained properly for effective recharge.(b)Clay sub-soil areas. - In places where the sub-soil formation is clay in nature the rate of percolation of rain water will be very slow and therefore provision of percolation/ recharge pit with bore, recharge trench with bore or deep recharge well are considered to be suitable for rain water harvesting.(i)Percolation/ recharge pit with bore. - It is similar to the one mentioned in sandy sub-soil formation except a bore hole at the bottom of the percolation pit which is also filled with the same permeable materials. A minimum size of 4!/ 2 inch diameter and 15 feet depth is normally required for one pit. However, if sand formation is available below the top clay layer, the bore has to be drilled preferably up to the sand formation. The number of these pits shall vary based on the extent of the area of water collection. On an average one unit is required for an area of 250 square feet. These structures are suitable for individual houses in general.(ii)Recharge trench with bore. - These are similar to the recharge pits but are longitudinal in shape and bore holes shall be provided at the bottom for every 10-15 feet of the trench. The trench and bore hole shall be filled with the same permeable materials such as broken bricks or pebbles or coarse sand, etc. These structures are suitable for apartments/ commercial complexes where the availability of rain water is more.(iii)Deep/ large recharge wells. - These are similar to the common open wells except in size and depth and are considered to be suitable for apartment/ commercial complexes. In general, a recharge well with 1.5 metre dia and 5.0 metre depth is required for a small apartment. Either brick wall or RCC (Reinforced concrete cement) concrete rings shall be used for construction. The top of the recharge well should be covered with RCC (Reinforced concrete cement) slab. The recharge wells shall be de-silted once in a year or two for effective recharge. Rain water collected from the rooftops of the buildings and open surfaces shall be diverted to these recharge structures through PVC (Poly vinyl chloride) pipe line or by providing channels on the ground. These structures should be maintained properly for effective recharge.(c)Hard-rock areas (weathered). - In hard lock areas also, the rate of percolation of rain wafer will be slow. Therefore, in order to collect and recharge rain water it would be preferable to construct recharge wells of appropriate size. Percolation pits with deep bore holes up to a depth of 50-100 feet shall be provided. In this case, the bore hole is to be constructed with slotted pipe for effective recharge. In general, construction of separate recharge structures shall be provided in the absence of existing infrastructures such as storage tank/ sump, open well or bore well in order to reduce the cost involved.(3)The owner or occupier of any building in existence on the 21st day of November, 2002-(a)provide roof top rain water harvesting structure wherever a storage tank or an open well or a bore well is available in the building irrespective of the nature of sub-soil conditions;(b)surface run-off water from the open spaces around the buildings, parks and playgrounds shall be harvested using appropriate recharge structures based on the nature of the sub-soil conditions.(i)Roof-top rain water harvesting - (a) Direct collection. - Rain water from the roof of the buildings such as tiled/ sloped terrace building and flat/ RCC (Reinforced concrete cement) roof shall be collected using appropriate size of gutters or PVC (Poly vinyl chloride) pipes and stored either in a collection tank or storage tank of appropriate size placed over the ground or underground through a filter unit. A filter chamber of appropriate size shall be provided to filter the dust particles usually present in the roof-tops of the buildings. Suitable filter material such as well-burnt broken bricks or coarse sand or small sized pebbles or blue metal gravels (baby chips) shall be used in the filter chamber. The surplus water available after filling the storage tank/ sump shall be diverted to the nearby open well or bore well or recharge pits. Proper disinfection shall be made while storing the water for long use.(b)Recharging the open well/ bore well. - The rain water collected from the rooftops of both tiled/ sloped roof and flat/ RCC (Reinforced concrete cement) roofs using gutters or PVC (Poly vinyl chloride) pipes shall be diverted to the open well or bore well through a filter chamber of appropriate size. Regular disinfection methods are to be practised while harvesting rain water in open wells.(ii)Harvesting surface run-off water. - Apart from the roof-top rain water harvesting, the rain water available in the open spaces around the buildings and in places/ buildings where a sump or open well or bore well is not available the rain water shall be harvested and recharged into the ground using appropriate recharge structures based on the nature of the sub-soil conditions as mentioned below:(a)Sandy sub-soil areas. - In places where the sub-soil formation is sandy in nature the rate of percolation of rain water will be more and therefore provision of shallow recharge structures such as percolation/ recharge pits, recharge trenches or shallow recharge wells are considered to be suitable for rain water harvesting.(i)Percolation/ recharge pits shall be provided around the buildings with minimum size of 1 metre x 1 metre x 1 metre and filled with permeehale medium such as broken bricks or pebbles or coarse sand, etc. The number of these pits shall vary based on the extent of the area of water collection. On an average one unit is required for an area of 250 square feet. These structures are suitable for individual houses in general.(ii)Recharge trenches (longitudinal in shape) similar to the percolation/ recharge pits are suitable for apartment/ commercial complexes, where the availability of rain water is more. Two or three of these structures shall be provided on the basis of the extent of the building.(iii)Shallow recharge wells are similar to the common open wells except in size and depth. Normally, for an individual house with 1000 square feet area, a recharge well with 1.0 metre dia and 3.0 metre dia depth is required. For apartments/ commercial complexes two or three recharge wells are required based on the extent of the building. Either brick wall or RCC (Reinforced concrete cement) concrete rings shall be used for construction. The top of the recharge well should be covered with RCC (Reinforced concrete cement) slab. Recharge wells are to be de-silted once in a year or two for its effective recharge. Rain water collected from the roof tops of buildings and open surfaces shall be diverted to these recharge structures through PVC (Poly vinyl chloride) pipe line or by providing channels on the ground. These structures shall be maintained properly for effective recharge.(b)Clay sub-soil areas. - In places where the sub-soil formation is clay in nature the rate of percolation of rain water will be very slow and therefore provision of percolation/ recharge pit with bore, recharge trench with bore or deep recharge well are considered to be suitable for rain water harvesting.(i)Percolation/ recharge pit with bore. - It is similar to the one mentioned in sandy sub-soil formation except a bore hole at the bottom of the percolation pit which is also filled with the same permeable materials. A minimum size of 4= inch diametre and 15 feet depth is normally required for one pit. However, if sand formation is available below the top clay layer, the bore has to be drilled preferably up to the sand formation. The number of these pits shall vary based on the extent of the area of water collection. On an average one unit is required for an area of 250 square feet. These structures are suitable for individual houses in general.(ii)Recharge Trench with Bore. - These are similar to the recharge pits but are longitudinal in shape and bore holes shall be provided at the bottom for every 10-15 feet of the trench. The trench and bore hole shall be filled with the same permeable materials such as broken bricks or pebbles or coarse sand, etc. These structures are suitable for apartments/ commercial complexes where the availability of rain water is more,(iii)Deep/ large recharge wells. - These are similar to the common open wells except in size and depth and are considered to be suitable for apartment/ commercial complexes. In general, a recharge well with 1.5 metre dia and 5.0 metre depth is required for a small apartment. Either brick wall or RCC (Reinforced concrete cement) concrete rings shall be used for construction. The top of the recharge well should be covered with RCC (Reinforced concrete cement) slab. The recharge well shall be de-silted once in a year or two for effective recharge. Rain water collected from the rooftops of the buildings and open surfaces shall be diverted to these recharge structures through PVC (Poly vinyl chloride) pipe line or by providing channels on the ground. These structures should be maintained properly for effective recharge,(c)Hard rock areas (Weathered). - In hard rock areas also, the fate of percolation of rain water will be slow Therefore, in order to collect and recharge the rain water it would be preferable to construct recharge wells of appropriate size. Percolation pit with deep bore holes up to a depth of 50-100 feet shall be provided. In this case, the bore hole is to be constructed with slotted pipe for effective recharge.In general, construction of separate recharge structures shall be provided in the absence of existing infrastructure such as storage tank/ sump, open well or bore well in order to reduce the cost involved.]
