Water Harvesting



RAINWATER HARVESTING & 

Environmental Conditions for Building and Construction

9.1 The RWH system

The harvesting of rainwater simply involves the collection of water from surfaces on which rain falls, and subsequently storing this water for use. The rainwater collected can be stored for direct use or can be recharged into the underground aquifers. In scientific terms water harvesting (broadly) refers to collection and storage of rainwater from the rooftops.  This also restricts evaporation and seepage into building foundations. All buildings having a plot size of 100 sq.m. or more, while submitting the building plans for sanction, shall mandatorily include the complete proposal of rainwater harvesting. 

A rainwater harvesting system consists of:

i. Roof catchment

ii. Gutters

iii. Down pipes

iv. Rain water/ Storm water drains

v. Filter Chamber

vi. Storage Tanks/ Pits/ Sumps.

vii. Ground Water recharge structures like pit, trench, tube well or combination of above structure. 

Rainwater Harvesting is a way to capture the rain runoff, store that water above ground or charge the underground aquifers and use it later. This happens naturally in open rural areas. But in congested, over-paved metropolitan cities, there is a need to devise methods to capture the rain water. The rainwater that is incident on the surface/ roof top is guided to bore wells or pits or new/old/ abandoned wells through small diameter pipes to recharge the underground water which can be used later whenever required.  

Rainwater can be harvested to the extent of 55,000 liters per 100sq. meters area per year from rooftops.

9.2 Rainwater harvesting techniques: 

There are two main techniques of rain water harvestings.

a. Storage of rainwater on surface for future use.

b. Recharge to ground water. 

The technical aspects and options of Rainwater harvesting from which the city authorities can assess and choose to adopt are placed at Annexure III to the bye-laws.

9.3 Harvesting provisions in various Building categories: 

All buildings in a city contribute to the rainwater runoff during the monsoon and hence such runoff can be harvested for water reuse/recharge. 

The indicative provisions of rainwater harvesting in various buildings types are: 

The number of recharge bores to be provided in different plot sizes shall be as below:

Environmental Conditions for Building and Construction  (Category “A”: 5000 sqmt - 20000 sqmt): 

Sl.No.  Medium Environmental conditions 

MBBL

Ref.Clause 

1

Natural Drainage 

The inlet and outlet point of natural drain system should be maintained with adequate size of channel for ensuring unrestricted flow of water -
2

Water conservations Rain Water Harvesting and Ground Water Recharge 

A rain water harvesting plan needs to be designed where the recharge bores (minimum one per 5000 sqm of built-up area) shall be provided. The rain water harvested should be stored in a tank for reuse in household through a provision of separate water tank and pipeline to avoid mixing with potable municipal water supply. The excess rain water harvested be linked to the tube well bore in the premise through a pipeline after filtration in the installed filters.  Table 9.1 
2a   The unpaved area shall be more than or equal to 20% of the recreational open spaces 10.2.1 (iv) 
3

Solid Waste

Management 

Separate wet and dry bins must be provided at the ground level for facilitating segregation of waste.  10.2.5(b)
4 Energy  In common areas, LED/ solar lights must be provided 10.2  3c) 
5

Air Quality 

and Noise 

Dust, smoke and debris prevention measures such as screens, barricading shall be installed at the site during construction. Plastic/ tarpaulin sheet covers must be used for trucks bringing in sand and material at the site -
5a   The exhaust pipe of the DG set, if installed, must be minimum 10m away from the building. In case it is less than 10m away, the exhaust pipe shall be taken up to 3m above the building -
6

Green

Cover 

A minimum of 1 tree for every 80 sqm of land shall be planted and maintained. The existing trees will be counted for this purpose. Preference should be given to planting native species 10.2.1 (i) 
6a   Where the trees need to be cut, compensatory plantation in the ratio of 1:3 (i.e. planting of 3 trees for every 1 tree that is cut) shall be done with the obligation to provide continued maintenance for such plantations 10.2.1 (ii)

Environmental Conditions for Building and Construction  (Category “B”: 20000 sqmt - 50000 sqmt): 

Sl.No.  Medium Environmental conditions 

MBBL

Ref.Clause 

1

Natural

Drainage 

The inlet and outlet point of natural drain system should be maintained with adequate size of channel for ensuring unrestricted flow of water -
2 Water conservations Rain Water Harvesting and Ground Water Recharge  A rain water harvesting plan needs to be designed where the recharge bores (minimum one per 5000 sqm of built-up area) shall be provided. The rain water harvested should be stored in a tank for reuse in household through a provision of separate water tank and pipeline to avoid mixing with potable municipal water supply. The excess rain water harvested be linked to the tube well bore in the premise through a pipeline after filtration in the installed filters table 9.1
2a   The unpaved area shall be more than or equal to 20% of the recreational open spaces 10.2.1 (iv)
3 Solid Waste Management  Separate wet and dry bins must be provided at the ground level for facilitating segregation of waste 10.2.5(b)
4 Energy  In common areas, LED/ solar lights must be provided.  10.2  3c) 
4a   At least 1% of connected applied load generated from renewable energy source such as photovoltaic cells or wind mills or hybrid should be provided.  10.2
4b   As per the provisions of the Ministry of New and Renewable energy solar water heater of minimum capacity 10 litres/4 persons (2.5 litres per capita) shall be installed.   1–.2.4 - IV 
4c   Use of flyash bricks: Fly ash should be used as building material in the construction as per the provisions of Fly Ash Notification of September, 1999 and as amended from time to time 10.2.6 (b) 
 
5

Air Quality

and Noise 

Dust, smoke and debris prevention measures such as screens, barricading shall be installed at the site during construction. Plastic/ tarpaulin sheet covers must be used for trucks bringing in sand and material at the site.  -
5a   The exhaust pipe of the DG set, if installed, must be minimum 10m away from the building. In case it is less than 10m away, the exhaust pipe shall be taken up to 3m above the building.  -
6 Green cover  A minimum of 1 tree for every 80 sqm of land shall be planted and maintained. The existing trees will be counted for this purpose. Preference should be given to planting native species.  10.2.1 (i) 
6a   Where the trees need to be cut, compensatory plantation in the ratio of 1:3 (i.e. planting of 3 trees for every 1 tree that is cut) shall be done with the obligation to provide continued maintenance for such plantations. 10.2.1 (ii) 

Environmental Conditions for Building and Construction  (Category “C”: 50000 sqmt - 150000 sqmt): 

Sl.No.  Medium Environmental conditions 

MBBL

Ref.Clause 

1

Natural Drainage 

The inlet and outlet point of natural drain system should be maintained with adequate size of channel for ensuring unrestricted flow of water.  -
2 Water  conservations – Rain Water Harvesting and Ground Water  Recharge A rain water harvesting plan needs to be designed where the recharge bores (minimum one per 5000 sqm of built-up area) shall be provided. The rain water harvested should be stored in a tank for reuse in household through a provision of separate water tank and pipeline to avoid mixing with potable municipal water supply. The excess rain water harvested is to be  linked to the tube well bore in the premise through a pipeline after filtration in the installed filters. table 9.1
2a   The unpaved area shall be more than or equal to 20% of the recreational open spaces. 10.2.1(iv)
2b   The ground water shall not be withdrawn without approval from the competent authorit  
2c   Use of potable water in construction should be minimized.  
2d   Low flow fixtures and sensors must be used to promote water conservation  
2e   Separation of grey and black water should be done by the use of dual plumbing system.  
3 Solid Waste Management Separate wet and dry bins must be provided at the ground level for facilitating segregation of waste 10.2.5(b)
3a   All non-biodegradable waste shall be handed over to authorized recyclers for which a written tie-up must be done with the authorized recyclers.   
3b   Organic waste composter/ vermiculture pit with a minimum capacity of 0.3 Kg/tenement/day must be installed wherein the STP sludge may be used to be converted to manure which could be used at the site or handed over to authorized recyclers for which a written tie-up must be done with the authorized recyclers.   
4 Energy In common areas, LED/ solar lights must be provided. 10.2.3(c)
4a   At least 1% of connected applied load generated from renewable energy source such as photovoltaic cells or wind mills or hybrid should be provided 10.2
4b   As per the provisions of the Ministry of New and Renewable energy solar water heater of minimum capacity 10 litres/4 persons (2.5 litres per capita) shall be installed.   10.2.4(iv)
4c   Use of flyash bricks: Fly ash should be used as building material in the construction as per the provisions of Fly Ash Notification of September, 1999 and as amended from time to time.  10.2.6(b)
4d   Use of concept of passive solar design of buildings using architectural design approaches that minimize energy consumption in buildings by integrating conventional energy-efficient devices, such as mechanical and electric pumps, fans, lighting fixtures and other equipment, with the passive design elements, such as building orientation, landscaping, efficient building envelope, appropriate fenestration, increased day lighting design and thermal mass.  10.2(3)
4e   Optimize use of energy systems in buildings that should maintain a specific indoor environment conducive to the functional requirements of the building by following mandatory compliance measures (for all applicable buildings) as recommended in the Energy Conservation Building Code (ECBC) 2007 of the Bureau of Energy Efficiency, Government of India.  10.2(3)
5

Air Quality

and Noise 

Dust, smoke and debris prevention measures such as screens, barricading shall be installed at the site during construction. Plastic/ tarpaulin sheet covers must be used for trucks bringing in sand and material at the site -
5a   The exhaust pipe of the DG set, if installed, must be minimum 10m away from the building. In case it is less than 10m away, the exhaust pipe shall be taken up to 3m above the building.  -
6 Green cover A minimum of 1 tree for every 80 sqm of land shall be planted and maintained. The existing trees will be counted for this purpose. Preference should be given to planting native species 40.201(ii)
6a   Where the trees need to be cut, compensatory plantation in the ratio of 1:3 (i.e. planting of 3 trees for every 1 tree that is cut) shall be done with the obligation to provide continued maintenance for such plantations.  40.201(ii)
7 Sewage Treatment Plant  Sewage treatment plant with capacity of treating 100% waste water shall be installed. Treated water must be recycled for gardening and flushing 4.32.4
8

Environment Management

Plan  

The environment infrastructure like Sewage Treatment Plant, Landscaping, Rain Water Harvesting, Power backup for environment, Infrastructure, Environment Monitoring, Solid Waste Management and Solar and Energy conservation, should be kept operational through Environment Monitoring Committee with defined functions and responsibility.  -
 

9.4 Rain Water Harvesting Provisions for Open spaces in cities  

The open spaces/recreational land use generally constitute regional parks, district parks, play ground and stadium, sports complex, monument zones, public parking, Plaza and other public open space. This may be as high as 30% to 50% of the city’s geographic area. All such public open spaces above the size of 500 sq.m. shall have arrangements for complete utilization and capture of storm water with scientific rain water harvesting arrangements. 

Following ideas may also be included:

i. Well cum Channel cum Percolation pits.

ii. Use of abandoned bore wells for recharging of ground water

iii. Artificial or natural Storage of storm water runoff from larger sites.

9.5 Ground Water Recharge  

Recharging of ground water should be made mandatory not only for residential buildings but for all types of buildings, including Group Housing Societies having a plot area more than 500 sq.m. and above. 

The Ground Water Recharge should also be mandatory for open spaces like parks, parking, plazas and playgrounds. The harvesting and recharge structures could be constructed by the Authority with the involvement of community based organizations like Resident Welfare Associations.

9.6 Enforcement and Monitoring  

a. The Authority shall constitute a Rainwater Harvesting Cell which will be responsible for enforcement and monitoring of the provisions of Rainwater Harvesting. The cell shall employ qualified persons who are well versed with the interpretation of Building Bye Laws and responsible for enforcement as well as monitoring the functioning of the Rainwater Harvesting System.  

b. The Authority shall include inspection of Rainwater Harvesting Structures before issuing Completion Certificates or NOCs for service connections to the property.

c. Set an example in the city by ensuring that Rainwater is harvested in the properties /assets owned by them including public buildings, markets, community centers, parking spaces, roads and parks etc.  

d. The Authority shall also establish a mechanism to monitor 100% of RWH provisions in all the buildings above 1000 sq.m. with annual physical verification, while buildings less than 1000 sq.m. can be monitored on the basis of 10% random survey by competent authority.  

e. With regard to open public spaces viz., Parks, playgrounds etc. the implementation of provision rainwater harvesting may be done with the help of Residents Welfare Associations, Community Building Organization and NonGovernmental Organizations.  

f. The Authority shall ensure earmarking budgetary provision for the creation and maintenance of rainwater harvesting structures in public spaces owned and maintained by them, like parking spaces, parks, plazas etc

g. The practice of incentives and penalties to promote rain water harvesting shall be formulated by the local authority based on best practices. Authority shall design its own incentive and penalty systems, considering the water level and scarcity. 

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