Rainwater harvesting cost in Chennai (Madras)
That buys a filter on the downpipe and a recharge pit with a 120 ft recharge bore, which sends about 1,11,690 litres of Chennai's rain back into the ground every year. The bore is the biggest cost, so the final price depends on how deep the water-bearing layer is under your plot.
Cost by building size in Chennai
Each recharge pit (2 × 2 × 2.5 m with a 120 ft bore) takes the water from a 25 mm downpour on about 280 m² of roof. Bigger roofs need more pits.
| Building | Roof area | Recharge pits | Water put back a year | Cost |
|---|---|---|---|---|
| Independent house | 100 m² (1,076 sq ft) | 1 | 1,11,690 L | ₹1.1 lakh to ₹1.7 lakh |
| Large house or villa | 250 m² (2,691 sq ft) | 1 | 2,79,225 L | ₹1.1 lakh to ₹1.7 lakh |
| Small apartment block or office | 600 m² (6,458 sq ft) | 3 | 6,70,140 L | ₹3.1 lakh to ₹4.8 lakh |
| Housing society, school or factory | 2,000 m² (21,528 sq ft) | 8 | 22,33,800 L | ₹8 lakh to ₹12 lakh |
How the bore depth changes the price
The same house with a 100 m² roof, with the recharge bore drilled to different depths. The depth is set on site from the soil and water levels.
What is included
| Item | Rate before GST |
|---|---|
| Recharge pit 2 × 2 × 2.5 m: digging, brick lining, concrete base and cover with manhole | ₹28,000 to ₹38,000 each |
| Filter media in the pit: boulders, gravel and coarse sand | ₹8,000 to ₹12,000 each |
| 150 mm recharge bore with slotted PVC pipe | ₹300 to ₹500 a foot |
| Filter chamber on the roof downpipe (gravel, charcoal and sand) | ₹12,000 to ₹20,000 each |
| Downpipe connections, mesh guards, first-flush diverter and overflow | ₹8,000 to ₹15,000 per building |
GST at 18% is added on top. A storage tank for reusing the water, paved-area drains and silt traps cost extra. Prices are TerraSetu's estimates for 2026 and are confirmed after a site survey.
Is it worth it in Chennai?
Chennai pumps out 122% of the groundwater that can safely be taken out each year (2025, Central Ground Water Board), rated over-exploited. The water table is falling, so every litre put back helps keep borewells running. A house system puts back about 11 water tankers of 10,000 litres a year.
Rainwater harvesting rules in Tamil Nadu
Tamil Nadu requires rainwater harvesting in every building, new and existing, public and private, with no size threshold. This rule dates from 2003. If an owner doesn't install it, the local body can install it and recover the cost like property tax, and the water connection can be cut until it is in place. In Chennai, Metrowater gives no new water or sewer connection without RWH.
Get a quote in Chennai
TerraSetu measures your roof, checks the soil and water level, and gives a fixed price for the system.
Frequently asked questions
What is the cost of rainwater harvesting in Chennai?
A rooftop rainwater harvesting system with a recharge pit for a house with a 100 m² (1,076 sq ft) roof costs about ₹1.1 lakh to ₹1.7 lakh in Chennai, including GST, with a 120 ft recharge bore. The bore depth makes the biggest difference to the price; larger buildings need more pits.
How much water does rainwater harvesting save in Chennai?
Chennai gets about 1,314 mm of rain a year, so a 100 m² roof sends about 1,11,690 litres into the ground each year, roughly 11 tankers of 10,000 litres.
How many recharge pits does a building need?
One 2 × 2 × 2.5 m pit with a recharge bore takes the water from a 25 mm downpour on about 280 m² of roof. A house usually needs one pit; a 2,000 m² society roof needs about eight.
How long does it take to install rainwater harvesting?
A house system usually takes three to seven days: a day or two to drill the bore, two or three to build and fill the pit, and a day to connect the downpipes and filter.
Is rainwater harvesting mandatory in Chennai?
Tamil Nadu requires rainwater harvesting in every building, new and existing, public and private, with no size threshold. This rule dates from 2003. If an owner doesn't install it, the local body can install it and recover the cost like property tax, and the water connection can be cut until it is in place. In Chennai, Metrowater gives no new water or sewer connection without RWH. In Chennai: Building plans are sanctioned only with RWH, and CMWSSB (Metrowater) withholds new water/sewer connections without it.
Rainwater harvesting cost in other districts of Tamil Nadu
- Ariyalur
- Chengalpattu
- Coimbatore
- Cuddalore
- Dharmapuri
- Dindigul
- Erode
- Kallakurichchi
- Kancheepuram
- Kanniyakumari
- Karur
- Krishnagiri
- Madurai
- Mayiladuthurai
- Nagapattinam
- Namakkal
- Perambalur
- Pudukkottai
- Ramanathapuram
- Ranipet
- Salem
- Sivagangai
- Tenkasi
- Thanjavur
- The Nilgiris
- Theni
- Thiruvarur
- Thoothukudi
- Tiruchirappalli
- Tirunelveli
- Tirupathur
- Tiruppur
- Tiruvallur
- Tiruvannamalai
- Vellore
- Villupuram
- Virudhunagar