Rainwater Harvesting Rules for Bangalore Homes: What BWSSB Requires
Rainwater harvesting is a legal duty for most houses and apartment buildings in Bangalore, and the water board checks for it when it bills a property. This guide explains which homes are covered, what the system has to do, what happens when a building has none and what a buyer of a house, plot or flat should check. The rules come from the Bangalore Water Supply and Sewerage Act and are run by BWSSB.
Where the rule comes from
The duty is set out in Section 72A of the Bangalore Water Supply and Sewerage Act, 1964. The section was added by an amendment in 2009 and was rewritten by a second amendment that the state notified in October 2021. BWSSB frames the detailed regulations and enforces them through its water connections.
The rule applies inside the BWSSB service area. It covers owners and occupiers, so a tenant's water bill is also affected when the building has no system. A buyer takes over the duty along with the property.
Which homes are covered
The Act works on the size of the site, which is the plot the building is on, and the common Bangalore plot sizes fall into the bands below.
| Site size | What the law requires |
|---|---|
| 30 x 40 ft (1,200 sq ft) and above, new buildings | A rainwater harvesting structure built along with the house, a rule in force since 2009 |
| 60 x 40 ft (about 2,400 sq ft) and above, existing and new buildings | A structure to store rainwater, use it and recharge groundwater |
| About 10,764 sq ft (1,000 sq m) and above, existing and new buildings | A rainwater harvesting structure with dual piping, so stored rainwater is used for purposes other than drinking, cooking and bathing |
The middle band is written in the Act as a site of 2,325 sq ft and more, which is 216 sq m. The 2021 amendment is what brought older buildings on these sites fully under the rule. Apartment projects are nearly always on sites above 1,000 sq m, so the dual-piping rule is the one that applies to them.
What a compliant system looks like
A harvesting system has a few simple parts. Gutters and downpipes carry rain from the roof, a filter removes leaves and silt, and the water then goes to a storage sump or tank, a recharge well, or both. Paved open areas around the building are counted as well as the roof.
BWSSB sets a minimum capacity that rises with the roof area and the paved area of the property. The capacity may be met through storage, through recharge or through a mix of the two. A recharge well is typically a ring well at least 3 m deep and about 0.9 m across, dug in the open part of the site.
The numbers explain why the city asks for this. Bangalore receives about 900 to 1,000 mm of rain in a year. A roof of 1,200 sq ft collects roughly 90,000 litres over that year, which is several months of non-drinking use for a small family.
What happens when a home has no system
Section 72A lets the Board build the structure itself when an owner fails to provide one. The cost is then recovered from the owner or occupier in the way unpaid land revenue is recovered. This power is rarely the first step, but it exists.
The everyday consequence is on the water bill. BWSSB adds a monthly surcharge, worked out as a share of the water and sanitary charges, to the bill of a property that has no system. The share rises after the first three months and is higher for non-domestic connections than for homes, and it continues until the system is built and reported to the Board.
BWSSB has revised these rates more than once. Ask the local BWSSB sub-division office for the rate in force before budgeting for it. The Board also runs a rainwater harvesting theme park in Jayanagar 5th Block, where designs for different plot sizes are on display.
What to check before buying a house or plot
For an independent house, the system is part of the building's legal standing, like the plan approval and the khata. The checks below take a few minutes on a site visit.
- Measure the site: 1,200 sq ft and 2,400 sq ft are the two sizes that matter for a house
- Find the downpipes, the filter and the sump or recharge well, and see that they are connected
- Ask the seller for the last three BWSSB bills and look for a rainwater harvesting surcharge
- Check that the sump is clean and that the recharge well is not sealed or filled with debris
- Ask whether the system has been reported to BWSSB and noted against the connection
- For a plot, add the cost of a sump, a filter and a recharge well to the construction budget
A missing system is easy to fix in a house with open space on the site. It is harder in a house that covers its whole plot, so look at where a recharge well would go. Any pending surcharge should be settled by the seller before registration.
What to check in an apartment project
In an apartment, the system belongs to the whole building and is maintained by the owners' association. A buyer should look at how the project handles rain across its roofs, podium and driveways. The points below are worth raising with the developer or the association.
- The number of recharge wells and the size of the rainwater sump
- Whether dual piping takes rainwater or treated water to flush tanks and gardens
- Whether the common-area water bill carries any surcharge
- Who cleans the filters and wells before each monsoon, and what it costs each year
A working system lowers tanker purchases in summer and reduces water standing in the basement and driveways during heavy rain. Both show up in the monthly maintenance charge. A project that depends on borewells gains the most, because recharge wells help keep those borewells running.
Cost and upkeep
For a house, the main costs are the pipes, the filter, the sump or tank and the recharge well. Most of these are cheapest when built with the house, since the sump and the pipes share work with the plumbing. Retrofitting an older house costs more, mainly for digging and for re-routing downpipes.
Upkeep is light. Clean the roof and the gutters before the first rains, wash the filter a few times each season and desilt the recharge well once a year. Keep the first rain of the season out of the sump, because it carries the dust of the dry months.
