Bengaluru’s water problems are no secret. Over the years, the city’s seen more and more contaminated sources, leading to a spike in waterborne diseases. Gated communities, which make up a major chunk of the city’s water demand, can actually play a huge role in tackling this.

Rainwater harvesting (RWH) is more than just an eco-friendly initiative. It offers practical, long-term benefits for both residents and the city at large. These include:

• Reducing collection and distribution costs

• Improving water quality, especially in areas with poor groundwater

• Minimising urban flooding and controlling non-point source pollution

• Extending the lifespan of home appliances by reducing scale build-up

• Cutting down water bills

• Ensuring water availability during summer shortages.

Recognising these advantages, the Bangalore Water Supply and Sewerage Board (BWSSB) has outlined specific guidelines for housing societies to set up efficient RWH systems. Here’s a clear breakdown of what you need to know.

Standard setup requirements 

For effective rainwater harvesting, BWSSB recommends a combination of storage and recharge methods. The guidelines are as follows:

• For rooftop areas, provide a storage/recharge capacity of 60 litres per square metre.

• For paved open spaces, allocate 30 litres per square metre.

Recharge wells should be at least 3 metres deep and 0.9 metres in diameter. It’s important to keep these wells open—avoid filling them with jelly or sand. Instead, use RCC rings layered with different sizes of jelly (40 mm to 6 mm) to support effective water infiltration.

Core components of a rainwater harvesting system

1. Catchment surface
The rooftop and open areas of your society serve as the primary catchment. Water quality will depend on roof material and nearby surroundings. Sloped roofs should be fitted with gutters and downpipes to guide water efficiently into the storage tank.

2. Gutters and downpipes
Gutters, typically made of PVC, vinyl, or aluminium, collect rainwater from the roof. They should be slightly sloped so that water flows towards downpipes. Downpipes usually 75–110 mm PVC carry this water to the storage tank. In RCC buildings, these components are often integrated into the existing drainage infrastructure.

3. Storage rank
This is the most critical and most expensive part of the system. The tank size should match the catchment area, rainfall pattern, and projected usage. Durability and accessibility for cleaning are important factors in choosing the right tank.

4. Filtration system
A filtration unit removes physical impurities. Sand bed filters are commonly used, incorporating layers of sand, charcoal, gravel, and pebbles.

• Wall-mounted filters work for rooftop areas up to 250 sq. m. For larger catchments, multiple units may be needed.

• A first-rain separator is essential for rooftops above 500 sq. m. It captures the first 1 mm of rainfall, usually the most contaminated, and stores it separately. A bypass valve allows residents to choose when or whether to harvest water during heavy rains.

Bengaluru often experiences rainfall intensities of up to 60 mm/hour, so the filtration system must be designed to handle this flow rate. Use filter materials like coarse sand, charcoal, and varying sizes of jelly stones, depending on your water quality requirements.

5. Delivery system
Once filtered, water must be channelled efficiently through pipes to the intended storage or distribution point. These pipes should be regularly checked for leaks and cleaned to maintain a consistent supply.

6. Water testing and treatment
Although rainwater appears clean, it’s essential to test it periodically, especially if it is intended for potable use. Treat the water using appropriate methods based on test results to ensure safety.

Ongoing maintenance guidelines

Maintenance plays a crucial role in the long-term success of your rainwater harvesting system. Here are the key practices to follow:

• Keep rooftops and nearby areas free of debris. Do not let scrap materials or detergent-rich water enter drains.
• Use perforated RCC slabs over drains for easy access and cleaning.
• Display signage within the society to raise awareness and promote good practices.
• Train support staff to maintain filters, clean drains, and manage recharge wells.
• Clear silt and debris from filter beds regularly.
• Ensure domestic wastewater does not mix with the recharge system.

RWH for paved areas

Most housing societies prefer paved surfaces for ease of access and maintenance. However, conventional paving can hinder water absorption. To allow for infiltration:

• Use porous pavements made with coarse aggregate.

• Lay a geotextile fabric beneath the paving to direct water into the soil.

• Opt for pre-cast tiles with holes, set on a sand base, to allow water to seep through.

The role of green cover

Incorporating greenery into your society’s landscape can significantly enhance rainwater absorption. Plant native trees at varying heights to slow down rain impact, improve water retention, and prevent soil erosion. Leaf litter also enriches the soil with humus, aiding moisture retention. A strong green cover complements your RWH system naturally.

To dive deeper into each specification and ensure your society meets all BWSSB standards, check out the downloadable PDF.

The Bangalore EV Charging Infrastructure Policy provides essential guidelines for setting up private EV charging stations within housing societies. Understanding and implementing these guidelines is beneficial for Resident Welfare Associations (RWAs) as the demand for electric vehicles (EVs) continues to rise. By setting up private EV charging stations, housing societies can offer residents the convenience of charging their vehicles at home, encouraging eco-friendly transportation adoption. By following these guidelines, RWAs can ensure their housing societies are prepared for the future of transportation, ultimately benefiting residents and contributing to a cleaner, greener city.

At the Building premise levels (for various building types)

• Private charging infrastructure (non-commercial use) for individuals.
• For all commercial modes of charging EVs, at least 1 PCS, as per minimum specifications laid under MoP guidelines.
• Standalone Battery Swapping Stations may be added to the PCs.

Residential Buildings (plotted house)
Table 1: Charging Infrastructure requirements for individual house/ self-use

Building Type	Plotted House
Ownership of Station	Private (Owner)
Connection and metering	Domestic meter
Type of charger	Slow chargers as per the owner’s specific requirement
Norms of provision	Min.1 SC and additional provisions as per the owner’s individual

Any PCS installed in Public/Private areas or building premises of any category that
caters to the commercial mode of charging of EVs shall be deemed as a Public Charging
Station and shall have to install the minimum requirements of chargers as specified in
the Guidelines dated 14.12.2018 of the Ministry of Power (refer to Annexure IV for MoP
Guidelines. However, to provide sufficient charging points for the EV share in
all vehicles the ratio of types of chargers is recommended in the table below –

Building Type	Any building type
Ownership of Station	Service provider
Connection and metering	Commercial Metering and Payment
Type of charger	As per minimum, requirements specified in MoP Guidelines
Additional chargers	PCS service providers shall install an additional number of kiosks/chargers beyond the minimum specified requirements to meet the ratio of charging points as prescribed below (by the type of vehicle)
Norms of Provisions for Charging Points	4Ws 1SC – each 3 EVs 1FC – each 10 Evs
	3Ws 1SC – each 2 EVs
	2Ws 1 SC – 2 EVs

Based on the occupancy pattern and the total parking provisions in the premises of the various building types, charging infrastructures shall be provided only for EVs, which are currently assumed to be 20% of all ‘vehicle holding capacity’/’parking capacity’ at the premise. Additionally, the building premise will have to have an additional power load, equivalent to the power required for all charging points.

Karnataka State Electrical Inspectorate has also provided its inputs on safety parameters to be considered for setting up an EV Charging Station which is as follows :

All Ev charging circuits must :

• Be supplied by a dedicated final sub-circuit.
• Be supplied from a sub-circuit protected by a voltage-independent RCD providing personal protection that is compatible with a charging supply for an electric vehicle.
• Provide an earth continuity monitoring system that disconnects the supply in the event that the earthing connection to the vehicle becomes ineffective. This monitoring system must fail to safety.
• Provide protection against the overload of the charging supply fittings.
• Provide protection against the overload of the incoming supply fittings.
• Be installed so that any socket outlet of supply is at least 800mm above the finished ground level. Use the armoured type from EVCS to Electric Vehicle and the maximum length should be retracted 5mtrs.

With the rise of electric vehicle usage in the city, the need for EV charging stations in your community becomes crucial. But what are the guidelines and regulations that one must adhere to set up an EV charging station in your community?

In 2019, the Ministry of Housing and Urban Affairs amended building codes to require EV charging stations in new private and commercial buildings. The Maharashtra EV Policy 2021 designates these charging stations as an ‘Amenity,’ directing the Urban Development Department and local bodies to identify locations for charging infrastructure, including at existing fuel stations, and reserve amenity spaces in City Development Plans. Housing societies must incorporate these provisions to ensure adequate EV charging infrastructure.

Setting up private charging stations at residences is permitted, with distribution companies (DISCOMs) facilitating the process. Urban local bodies are encouraged to offer property tax rebates for private charging infrastructure within residential premises. Electric Vehicle Service Equipment (EVSE) must be type-tested by a reputable authority. Private car batteries can be charged using domestic charging points, with billing typically included in home/domestic metering.

At the Building premise levels (for various building types)

• Private charging infrastructure (non-commercial use) for individuals.
• For all commercial modes of charging EVs, at least 1 PCS, as per the minimum specifications laid under the MoP guidelines.
• Standalone Battery Swapping Stations may be added to the PCs.

Residential Buildings (plotted house)
Table 1: Charging Infrastructure requirements for individual house/ self-use

Building Type	Plotted House
Ownership of Station	Private (Owner)
Connection and metering	Domestic meter
Type of charger	Slow chargers as per the owner’s specific requirement
Norms of provision	Min 1 SC and additional provisions as per the owner’s individual

Any PCS installed in Public/Private areas or building premises of any category that caters to the commercial mode of charging of EVs shall be deemed as a Public Charging Station and shall have to install the minimum requirements of chargers as specified in the guidelines dated 14.12.2018 of the Ministry of Power (refer to Annexure IV for MoP
Guidelines. However, to provide sufficient charging points for the EV share in for all vehicles, the ratio of types of chargers is recommended in the table below –

Building Type	Any building type
Ownership of Station	Service provider
Connection and metering	Commercial Metering and Payment
Type of charger	As per minimum requirements specified in the MoP Guidelines
Additional chargers	PCS service providers shall install an additional number of kiosks/chargers beyond the minimum specified requirements to meet the ratio of charging points as prescribed below (by the type of vehicle)
Norms of Provisions for Charging Points	4Ws 1SC – each 3 EVs 1FC – each 10 Evs
	3Ws 1SC – each 2 EVs
	2Ws 1 SC – 2 EVs

Based on the occupancy pattern and the total parking provisions in the premises of the various building types, charging infrastructures shall be provided only for EVs, which are currently assumed to be 20% of all ‘vehicle holding capacity’/’parking capacity’ at the premises. Additionally, the building premises will have to have an additional power load, equivalent to the power required for all charging points.

For the safe and effective Functioning of the EV Charging Stations (EVCS), the following guidelines must be followed:

1. Charging stations installed by Housing societies, provided that such stations meet the technical, Safety as well as performance standards and protocols laid down by the Central Electricity Authority (Technical Standards for Connectivity of the Distributed Generation Resources) Amendment Regulations 2019 and Central Electricity Authority (Measures related to Safety and Electric Supply) Amendment Regulations 2019) Maharashtra Fire Prevention and Life Safety Measures Act, 2006 and Directives issued from Urban Local Bodies Time to time.
2. All the electrical installation work for the charging station shall be carried out by the Licensed Electrical Contractor approved by the state government of Maharashtra.
3. Where multiple chargers are in use, there should be clear and prominent notices at each charging point indicating for which equipment or vehicle(s) i.e., AC or DC it is suitable.
4. Where rapid charging points – known as DC fast charge and operating at 500V DC – are provided, they should be differentiated from conventional charging points because of the hazards associated with the direct current. Measures should be taken to ensure that signs and labels associated with these chargers are not removed or defaced.
5. Where charging points are to be provided in multistorey car parks, consideration should be given to locating these in the open air at roof deck level to minimize the potential for fire spread within the structure.
6. All electric vehicle charging points shall be installed so that any socket-outlet of supply is at least 800 millimeters above the Highest Flood level.
7. The electric vehicle parking place shall be such that the connection to the vehicle when parked for charging shall be within five meters from the electric vehicle charging point.
8. The charging point should be child-proof and preferably installed away from any children’s play area.
9. Charging bays should be signed and marked prominently on the ground to allow vehicles to park close to the charging point and prevent the stretching of charging cables. The length of charging cables should be sufficient to allow their use with the intended equipment without risk of damage.
10. Charging points should be protected against mechanical damage by vehicles. They should be installed above ground level and be located on a raised island, or be protected by Krebs, bollards, or metal barriers. Charging points should also be protected against the ingress of water and foreign objects.
11. The parking of other vehicles in charging areas should be prohibited. In some cases, the introduction of barriers or other physical measures to prevent charging bays from being used as conventional parking spaces may need to be considered.
12. Where it is not practicable to provide this degree of physical separation of a vehicle
    charging area within a building, as mentioned above (and outside the premises), no charging should be undertaken within 10m of any combustible materials: be they waste materials, stock, or combustible elements of the structure. Similarly, no charging should be undertaken within 15m of hazardous installations such as transformers, flammable liquid stores, and liquefied petroleum gas tanks.
13. All chargers and associated equipment should be installed, used, and maintained by the manufacturer’s instructions. Servicing and maintenance should be carried out by a competent licensed electrician.
14. Electric Vehicle Supply Equipment (EVSE) shall be type tested by an agency /lab accredited by the National Accreditation Board for Testing and Calibration Laboratories (NABL) or any other regulatory authority for this purpose from time to time.
15. Where the connection point is installed outdoors or in a damp location, the equipment shall have a degree of Ingress Protection Code following IEC 60529.

The city of Mumbai is currently under intense water stress, with the water demand exceeding the water supply almost twofold. Gated communities comprising a significant portion of the demand, should look to alternate sources to ensure a steady supply for their resident and a means of precaution in a time of constant heatwaves and contaminated water sources.

The Brihanmumbai Municipality Corporation has therefore taken steps towards a category – B action plan of augmenting the water supply by looking into alternate sources of water.

Why RWH is required in Mumbai housing societies?

To address the current and future needs of your housing society. Due to excessive water extraction, there has been a significant drop in the freshwater level. When this happens, the natural barrier that prevents seawater from seeping inland is disrupted. As the freshwater level falls below that of the seawater, seawater begins to infiltrate our land. This not only affects our water supply but also poses a risk to the structural integrity of our buildings, as the seawater can come into contact with and corrode pile foundations.

By implementing rainwater harvesting, your society can help maintain the freshwater barrier, prevent seawater ingress, and ensure a sustainable and safe water supply for all residents.
Hence Mumbai Municipal Corporation made Rain Water Harvesting (RWH)
mandatory to the properties having plot area of more than 1000 sq. mts. after 1st Oct. 2002. Recycling has been made compulsory for buildings having centralized (water-cooled) A.C. plants. M.C.G.M. had granted residential water connections at 90 Ipcd i.e. no municipal water for flushing requirement.

Rainwater Harvesting Methods

The following techniques are used for Urban rainwater harvesting:

1. Storage in artificial above or underground tanks.
2. Recharging aquifer directly through existing dug-up wells & bore wells.
3. Recharging aquifer by percolation/soakage into the ground.
4. Pumping (putting under pressure) rainwater into the soil to prevent seawater ingress.

But before adopting any of these methodologies teaching oneself holistic
approach i.e. water reuse, recycling, and water conservation is a must.

Rubbing alcohol

It is necessary to ensure that the groundwater is not contaminated by mixing of
sewage/sullage or other impurities e.g. chemical/biological etc. So there should not
be any leakages in the premises, where the RWH system is to be installed. Societies should maintain their premises clean. Terraces should be cleaned before monsoon & be kept locked during monsoon. Pets should not be permitted there. Similarly, the street flood water in monsoon is contaminated. So it also should not be mixed with the RWH system. A mistake made by one person directly charging the aquifer can affect a number of persons at a time & there is no easy solution to clean the contaminated groundwater.

Paving

In housing societies, paved open spaces are often preferred for low maintenance and car parking, but they prevent water percolation. To balance paving needs and water absorption, avoid unnecessary paving. Instead, use porous pavements made with a higher percentage of coarse aggregate. These can include a geotextile layer at the bottom to direct water to specific areas. Additionally, pre-cast tiles with center holes set on sand bedding will facilitate better water percolation.

Forest

Understanding the relationship between soil, water, and green spaces is crucial for housing societies. Planting diverse tree varieties at different heights increases water retention by creating natural obstructions with their leaves and branches, slowing down rainfall. Fallen branches on the ground also help slow water flow. Humus from decomposed leaves releases water gradually and prevents soil erosion. As a result, areas with more trees have better water retention. To conserve soil and water, housing societies should maintain green cover and plant as many indigenous tree varieties as possible, which also supports the local ecosystem.

What are other regulations regarding rainwater harvesting?

The BMC’s health department looks into the maintenance of rainwater harvesting systems, particularly the prevention of mosquito infestation and cleanliness.

The legal perspectives have been developed from various guidelines issued by various departments and Acts. The Model Building Bye Laws (MBBL), 2016 framed by the Union Ministry for Housing have included guidelines for setting up RWH. The Maharashtra State Water Policy, 2019 mandates the conservation of rainwater and makes rainwater harvesting mandatory in urban areas.
The Development Control and Promotion Regulations (DCPR-2034) contain detailed provisions for rainwater harvesting for recharging the groundwater. The DCPR also contains provisions to ensure that rainwater naturally percolates into the ground in open spaces. The Maharashtra Groundwater (Development and Management) Act, 2009 also looks at the management of groundwater.

How can Mumbaikars set up rainwater harvesting?

Since Mumbai generally receives rainfall by large-intensity showers, it may not be always possible to ensure absorption of water at the rate of rainfall. A large quantity of runoff water could be wasted. Therefore it is better to collect rooftop runoff in artificial tanks, which would suffice flushing demand for a few days.

The BMC has stipulated the details of construction as follows:

1. 1. The following systems may be adopted for harvesting the rainwater drawn from the terrace and the paved surface :
      i. Open well of a minimum of 1.00 mt. dia and 6 mt. in depth into which rainwater may be channeled and allowed after filtration for removing silt and floating material. The well shall be provided with ventilating covers. The water from the open well may be used for nonpotable domestic purposes such as washing, flushing, and for watering the garden etc.
      ii. Raid Water Harvesting for recharge of groundwater may be done through a bore well around which a pit of one-metre width may be excavated up to a depth of at least 3.00 mt. and refilled with stone aggregate and sand. The filtered rainwater may be channeled to the refilled pit for recharging the borewell.
      iii. An impervious surface / underground storage tank of required capacity may be constructed in the setback or other open space and the rainwater may be channeled to the storage tank. The storage tank shall always be provided with ventilating covers and shall have draw-off taps suitably placed so that the rainwater may be drawn off for domestic, washing gardening, and other purposes. The storage tanks shall be provided with an overflow.
      iv. The surplus rainwater after storage may be recharged into the ground through percolation pits or trenches or a combination of pits and trenches. Depending on the geomorphological and topographical condition, the pits may be of the size of 1.20 mt. width X 1.20 mt. length X 2.00 mt. to 2.50 mt. depth. The trenches can be 0.60 mt width X 2.00 to 6.00 mt. length X 1.50 to 2.00 mt. 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 the upper middle layer up to 20% of the depth
      d) A thin layer of fine sand as the top layer
      e) The 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 waterfalls 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 loose 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.
      v) If the open space surrounding the building is not paved, the top layer up to a sufficient depth shall be removed and refilled with course sand to allow percolation of rainwater into the ground. 
   2. The terrace shall be connected to the open well/borewell/storage tank / recharge it/trench using HDPE / PVC pipes through filter media. A valve system shall be provided to enable the first washings from the roof or terrace catchment, as they would contain undesirable dirt. The mouths 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 diameter. For a roof area of 100 sq.mt.
   3. Rainwater harvesting structures shall be sited so as not to endanger the stability of buildings or earthwork. The structures 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.
   4. 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 will be utilized for drinking and/or cooking purposes, it shall be ensured that proper filter arrangement and a separate outlet for by-passing the first rainwater has been provided. Provided further that it will be ensured that for such use, proper disinfectants and water purification arrangements have been made.

The Karnataka Cooperative Societies Act (1959) has written the model bylaws that pertain to cooperative housing societies.
Bylaws benefit residents and Resident Welfare Associations by ensuring orderly and harmonious community living.

These regulations establish clear guidelines for property use, setbacks, and green spaces, contributing to a well-planned environment that enhances the neighborhood’s aesthetic appeal. By promoting these standards, bylaws help maintain property values and ensure that developments complement the existing community fabric. They also provide a framework for resolving disputes related to land use and property boundaries, fostering a peaceful and cohesive community atmosphere.

Read more.

The bylaws of Mumbai are a set of regulations and guidelines established to ensure the orderly and efficient functioning of the city. These rules cover various aspects, including building construction, waste management, public safety, and community living standards. Enforced by local municipal bodies, these bylaws aim to promote sustainable urban development, safeguard public health, and enhance the quality of life for residents. Adherence to these bylaws is essential for maintaining the city’s infrastructure, environment, and overall harmony within the community.

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