Rooftop rainwater recharge
Pipe roof water through a silt trap and filter into a recharge pit or an old borewell. Every 100 m² of roof puts back tens of thousands of litres a year, right where the pumping happens.
Groundwater level in Chennai (Madras)
122%Over-exploited
This area pumps out more water than rain puts back. That is the 2025 stage of groundwater extraction: water pumped out in a year as a share of what rain and other sources safely put back. Down 50 points since 2017.
109 million m³pumped out each year (2025)
89.2 million m³can be taken out safely each year
19.3 million m³yearly shortfall drawn from stored water
2%goes to irrigation; the rest to homes and industry
Extraction since 2009
Each point is one CGWB assessment. Over-exploited means more water leaves the ground than comes back, so the water table keeps falling. Hover over or tap a point to see why it moved.
Safe · up to 70%Semi-critical · 70–90%Critical · 90–100%Over-exploited · above 100%
Show the numbers
| Year | Stage | Pumped out | Safe limit | Category | What changed |
|---|---|---|---|---|---|
| 2009 | 406.0% | – | – | Over-exploited | First assessment in this series. |
| 2013 | 185.0% | 27.7 million m³ | 15.0 million m³ | Over-exploited | Down 221 points since 2009. |
| 2017 | 171.9% | – | – | Over-exploited | CGWB changed its method in 2017 (GEC-97 to GEC-2015), so part of this change comes from the new method. |
| 2020 | 143.2% | 67.6 million m³ | 47.2 million m³ | Over-exploited | Down 29 points since 2017. |
| 2022 | 133.0% | 129 million m³ | 96.7 million m³ | Over-exploited | Pumping up 90% (68 → 129 million m³). Safe limit up 105% (47 → 97 million m³). Main reason: more water soaked back into the ground, from better rain, canals or recharge structures. A swing this large usually comes partly from revised estimates (a new well count or changed district boundaries), not only from changes on the ground. |
| 2023 | 127.5% | 118 million m³ | 92.2 million m³ | Over-exploited | Pumping down 9% (129 → 118 million m³). Safe limit down 5% (97 → 92 million m³). Main reason: less water was pumped out, mostly for homes and industry (126 → 115 million m³). |
| 2024 | 124.9% | 116 million m³ | 93.0 million m³ | Over-exploited | Pumping down 1% (118 → 116 million m³). Safe limit up 1% (92 → 93 million m³). |
| 2025 | 121.7% | 109 million m³ | 89.2 million m³ | Over-exploited | Pumping down 7% (116 → 109 million m³). Safe limit down 4% (93 → 89 million m³). Main reason: less water was pumped out, mostly for homes and industry (114 → 107 million m³). |
Million m³: 1 million m³ = 100 crore litres. 2009 and 2013 used the older GEC-97 method.
Loading 20 years of rainfall…
Ponds and lakes in Chennai
147 of 305 water bodies (48%) are not in use: dried up, silted, built over or polluted. Bringing them back is one of the cheapest ways to recharge groundwater.
Loading the map of water bodies in Chennai…
- Ponds142
- Tanks126
- Lakes24
- Others13
Source: 1st Census of Water Bodies, Ministry of Jal Shakti (counted in 2018-19, published 2023).
What will fix it here
Most of the water here goes to homes and industry, so rooftop recharge and reuse make the biggest difference.
Treat and reuse wastewater
Treated water from a sewage treatment plant can run flushing, gardens, cooling towers and construction, which today often draw on borewells.
Recharge pits and shafts in open land
Parks, campuses, warehouse yards and road sides can take recharge shafts that reach past the clay layer, so runoff that floods streets goes down to the aquifer instead.
Meter borewells and fix leaks
Metered and registered borewells, leak repairs in supply lines and water-efficient fixtures cut pumping without anyone going short.
Revive village ponds and johads
Desilting old ponds and opening their feeder channels restores natural recharge. A one-hectare pond that soaks in a metre of water over the monsoon puts back about a crore litres.
Permeable paving and green cover
Porous pavers, unpaved tree pits and bioswales along roads let rain soak in instead of racing to the drain.
Frequently asked questions
What is the groundwater level in Chennai?
In the 2025 Central Ground Water Board assessment, Chennai (Tamil Nadu) pumped out 122% of the groundwater that can be safely taken out each year, which puts it in the "over-exploited" category. That is 50 points lower than in 2017.
Is groundwater in Chennai over-exploited?
Yes. Chennai takes out more groundwater than rain and other sources put back, so the water table keeps falling.
How can groundwater be recharged in Chennai?
Rooftop rainwater harvesting into recharge pits or old borewells, recharge shafts in open land, reviving ponds, check dams, treating and reusing wastewater, and moving farms to drip irrigation and less thirsty crops.
How many ponds and lakes are there in Chennai?
The first Census of Water Bodies counted 305 water bodies in Chennai, including 142 ponds. 147 of them were not in use.
Other districts in Tamil Nadu
Salem148%Tirupathur143%Vellore122%Dindigul117%Mayiladuthurai117%Namakkal116%Perambalur106%Karur103%Thanjavur101%Krishnagiri92%Coimbatore92%Dharmapuri90%Tiruvannamalai86%Tiruppur86%Villupuram85%Tiruchirappalli85%Ranipet85%Theni84%Kallakurichchi81%Erode77%Tenkasi76%Madurai70%Virudhunagar64%Chengalpattu64%Cuddalore63%Tiruvallur55%Thiruvarur54%Pudukkottai49%Kancheepuram49%Ariyalur48%Tirunelveli41%Thoothukudi28%Sivagangai26%Kanniyakumari14%The Nilgiris13%Ramanathapuram11%Nagapattinam0.0%