Switch thirsty crops, water by drip
Where most water goes to fields, moving from paddy and sugarcane to millets, pulses or maize, and from flood to drip or sprinkler irrigation, saves more than any recharge can add.
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 15 points since 2017.
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.
| Year | Stage | Pumped out | Safe limit | Category | What changed |
|---|---|---|---|---|---|
| 2009 | 134.0% | – | – | Over-exploited | First assessment in this series. |
| 2013 | 122.0% | 262 million m³ | 215 million m³ | Over-exploited | Down 12 points since 2009. |
| 2017 | 120.4% | – | – | Over-exploited | CGWB changed its method in 2017 (GEC-97 to GEC-2015), so part of this change comes from the new method. |
| 2020 | 118.2% | 254 million m³ | 215 million m³ | Over-exploited | Little change since 2017 (-2.3 points). |
| 2022 | 113.4% | 262 million m³ | 231 million m³ | Over-exploited | Pumping up 3% (254 → 262 million m³). Safe limit up 8% (215 → 231 million m³). Main reason: more water soaked back into the ground, from better rain, canals or recharge structures. |
| 2023 | 109.4% | 250 million m³ | 228 million m³ | Over-exploited | Pumping down 5% (262 → 250 million m³). Safe limit down 1% (231 → 228 million m³). Main reason: less water was pumped out, mostly for irrigation (258 → 244 million m³). |
| 2024 | 109.4% | 251 million m³ | 229 million m³ | Over-exploited | Pumping up 0% (250 → 251 million m³). Safe limit up 0% (228 → 229 million m³). |
| 2025 | 105.8% | 275 million m³ | 260 million m³ | Over-exploited | Pumping up 10% (251 → 275 million m³). Safe limit up 14% (229 → 260 million m³). Main reason: more water soaked back into the ground, from better rain, canals or recharge structures. |
Million m³: 1 million m³ = 100 crore litres. 2009 and 2013 used the older GEC-97 method.
Loading 20 years of rainfall…
629 of 1,078 water bodies (58%) 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 Perambalur…
Source: 1st Census of Water Bodies, Ministry of Jal Shakti (counted in 2018-19, published 2023).
Most of the water here goes to farming, so using less on fields matters as much as recharge.
Where most water goes to fields, moving from paddy and sugarcane to millets, pulses or maize, and from flood to drip or sprinkler irrigation, saves more than any recharge can add.
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.
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.
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.
On sloping or rocky land, small dams on seasonal streams and trenches along contours slow water down long enough for it to sink in.
Treated water from a sewage treatment plant can run flushing, gardens, cooling towers and construction, which today often draw on borewells.
In the 2025 Central Ground Water Board assessment, Perambalur (Tamil Nadu) pumped out 106% of the groundwater that can be safely taken out each year, which puts it in the "over-exploited" category. That is 15 points lower than in 2017.
Yes. Perambalur takes out more groundwater than rain and other sources put back, so the water table keeps falling.
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.
The first Census of Water Bodies counted 1,078 water bodies in Perambalur, including 442 ponds. 629 of them were not in use.
Yearly rain at Perambalur, 2006–2025, from NASA satellite data. Lighter bars are dry years (20% or more below average), when wells are drawn hardest.
To stop the water table falling, Perambalur has to put back or save 15.2 million m³ a year. At 917 mm of rain, here is what that looks like:
In practice it is a mix: recharge in towns, ponds and check dams in villages, and saving water on farms and in factories.
1 mm of rain on 1 m² is 1 litre. The surface factor allows for water lost to splash, evaporation and first-flush.