Resources · Water
Rainwater harvesting in Gujarat: how much your roof can collect, the methods, the building rules and the schemes
Rainwater harvesting means catching rain where it falls and either storing it or sending it underground to recharge groundwater. This page works out how much water a roof in Ahmedabad can collect, explains each method and when to use it, sets out what Gujarat’s building regulations require, and lists the government schemes that fund water conservation. Every figure carries its source.
Why it matters
Gujarat’s groundwater, in the latest official figures
The Central Ground Water Board’s Dynamic Ground Water Resources Assessment 2025, released on 18 December 2025, puts Gujarat’s stage of groundwater extraction at 55.95%: the share of the usable annual recharge that is being pumped out.
27.58 bcm
Billion cubic metres of groundwater replenished each year in Gujarat.
25.61 bcm
The part of that recharge that can be used each year.
14.33 bcm
What is actually drawn out each year, for farming, homes and industry.
55.95%
Below the national figure of 60.63%.
Sizing
How much rainwater can your roof collect?
One millimetre of rain on one square metre of roof is one litre of water. The harvestable volume is roof area × rainfall × runoff coefficient, the share of rain that actually runs off the roof. The Bureau of Indian Standards guideline IS 15797:2008 puts roof runoff coefficients at about 0.8 to 0.95.
| Roof area | Typical building | Water a year in Ahmedabad |
|---|---|---|
| 50 m² | Small house | about 33,000 litres |
| 100 m² | Bungalow or row house | about 66,000 litres |
| 250 m² | School block or small apartment building | about 1.65 lakh litres |
| 1,000 m² | Housing society terraces combined | about 6.6 lakh litres |
Worked on 824 mm a year, the India Meteorological Department’s average for Ahmedabad over 2010–2019, and a runoff coefficient of 0.8. Most of it falls between June and September, so storage alone cannot hold a year’s rain: the surplus is best sent into the ground.
Work it out for your roof
About 65,920 litres a year
Uses a runoff coefficient of 0.8.
Methods
Rainwater harvesting methods, and when to use each
Rooftop storage tank
Roof water is piped through a filter into a sump or tank for later use. Best where water is short in the dry months and the roof is clean.
Recharge pit
A shallow pit filled with graded boulders, gravel and sand, so roof or yard water soaks into the ground. Suits small plots.
Recharge trench
A long, narrow pit that gives water more area to percolate. Used along compound walls and in larger campuses.
Percolating well or recharge shaft
A vertical shaft that carries water through clay layers to permeable strata below. This is the structure Gujarat’s building rules call for on larger plots.
Borewell and dug-well recharge
Directing filtered water into an existing well. The Central Ground Water Board requires water for well recharge to be treated first, so the aquifer is not polluted or clogged.
Check dams, farm ponds and percolation tanks
Small barriers across streams and ponds in fields hold runoff long enough for it to seep in. The mainstay of rural water conservation in Gujarat.
Building rules
What Gujarat’s building regulations require
Regulation 17.2.2 of the Comprehensive General Development Control Regulations, 2017 (CGDCR) makes rainwater harvesting mandatory for buildings with a ground coverage of 80 square metres or more.
| Building-unit area | What is required |
|---|---|
| 80 – 500 m² | A percolation pit or bore recharge in the open space around the building |
| 500 – 4,000 m² | A percolating well with a rainwater harvesting system |
| Above 4,000 m² | One percolating well for every 4,000 m², or a water retention pond of at least 3,00,000 litres together with a reduced number of wells |
| Above 1,000 m² | A rainwater storage tank is also mandatory (Regulation 17.2.3) |
Schemes
Government schemes for water conservation in Gujarat
Sujalam Sufalam Jal Abhiyan
The state’s pre-monsoon drive to deepen lakes, desilt and repair check dams and clean canals, with public participation. The 2026 edition began on 23 February 2026; the state reported 13,315 works and 20,789 lakh cubic feet of added storage this year, and 1,38,039 lakh cubic feet over eight years (as reported by ANI and DD News).
Jal Sanchay Jan Bhagidari
Launched on 6 September 2024 at a programme in Surat, with the Prime Minister joining by video, to build about 24,800 rainwater harvesting structures across Gujarat through community effort. Surat district reported 56,756 structures and ranked first in its category in the first awards (PIB, November 2025).
Catch the Rain
“Catch the rain, where it falls, when it falls.” Launched on 22 March 2021 under the Jal Shakti Abhiyan. The 2026 edition, run with Jal Sanchay Jan Bhagidari, began on 1 June 2026 with a focus on over-exploited and critical districts.
Atal Bhujal Yojana
A central scheme for community-led groundwater management in seven states, including Gujarat, where it covers 36 blocks according to a 2025 PIB release.
Amrit Sarovar
Creation and revival of village ponds. Gujarat had completed 2,650 Amrit Sarovars by 20 March 2025 (Department of Rural Development).
Khet talavadi (farm ponds)
Gujarat supports farm ponds for storing monsoon runoff. In 2026 applications for free geomembrane lining were taken online through the state’s g-talavadi portal and closed on 15 May 2026, as reported by Sandesh. Check the portal for the current round.
Ahmedabad
Rainwater harvesting in Ahmedabad
The Ahmedabad Municipal Corporation has backed percolating wells in housing societies, with the corporation reported to meet 80% of the cost and the society 20% (Times of India, April 2022). In 2024 it allowed councillors to spend their budgets on percolating wells, and in November 2025 it approved a tender to fit rooftop rainwater harvesting on 1,230 municipal buildings. We found no property-tax rebate for rainwater harvesting currently offered in Ahmedabad. Ask your ward office about the society scheme before building.
Our work
Where Scapex Foundation fits
Water conservation is part of our Scapex Prakriti division: check dams, farm ponds, village-pond desilting and school rooftop systems, planned with the community and measured by one indicator — whether each structure is still working twelve months after it is built. Housing societies and companies planning a CSR water project can talk to us. See also India’s forest and tree cover, where the same gap between what is built and what survives shows up in the national planting figures. See our environment work on the home page.
Questions
Frequently asked questions about rainwater harvesting
Yes, for new buildings with a ground coverage of 80 square metres or more. Regulation 17.2.2 of the Comprehensive General Development Control Regulations, 2017 requires a percolation pit or bore recharge on smaller plots and percolating wells on larger ones, and Regulation 17.2.3 adds a storage tank for building units above 1,000 square metres.
About 660 litres a year for every square metre of roof, using the India Meteorological Department’s 2010–2019 average of 824 mm and a runoff coefficient of 0.8. A 100 square metre roof collects about 66,000 litres a year.
Only after filtering. Discard the first flush from the roof and pass the rest through a sand, gravel and boulder filter. The Central Ground Water Board requires water for well recharge to be treated so that it does not pollute or clog the aquifer. Never send sewage or wastewater into a recharge well.
Usually both. Most of Gujarat’s rain falls between June and September, far more than a household tank can hold, so store what you can use and send the surplus into a recharge pit or percolating well. IS 15797:2008 notes that recharge suits areas where the water table is deeper than about 8 metres.
Gujarat’s annual pre-monsoon water conservation campaign, running since 2018. It deepens lakes, desilts and repairs check dams and cleans canals and drains with public participation, so that more monsoon water is held and recharged.
The Central Ground Water Board’s 2025 assessment puts Gujarat’s stage of groundwater extraction at 55.95%, below the national 60.63%. The state average hides wide local variation, so check the category of your own block or taluka.