Environment
Groundwater is running out across India because we pump far more than the rain puts back. In villages and other large open spaces, rainwater can be slowed down and sent back into the ground. This guide explains eight proven rainwater harvesting methods, where each one works and how it is built.
Fresh water on earth is a scarce resource. Fresh water makes up only about 3% of the total water on earth; the rest is saline water in the oceans. According to India’s groundwater guidance, about 11% of the total fresh water available on earth is groundwater that can be reached up to a depth of 800 m for everyday use. Exploitation and mindless extraction of groundwater have caused its rapid depletion and deterioration, which is why rainwater harvesting and groundwater recharge matter so much today.
Rainwater harvesting methods for spacious areas
In rural areas, surface spreading techniques are commonly used because ample space is available, allowing a larger quantity of water to be recharged. The methods below can be used for rainwater harvesting and groundwater recharge, helping to control rainwater runoff that flows down slopes, rivers, streams and nalas.
Gully plug method
Gully plugs are built using local stones, clay and bushes across small gullies and streams running down hill slopes, which carry drainage to tiny catchments during the rainy season. Gully plugs help conserve soil and moisture. Sites for gully plugs may be chosen wherever there is a local break in slope that allows enough water to collect behind the bunds.
Contour bunding method
Contour bunds are an effective way to conserve soil moisture in watersheds for a long time. They suit low-rainfall areas, where monsoon runoff can be held by building bunds on sloping ground all along the contour of equal elevation.
Flowing water is stopped before it gains erosive speed by keeping suitable spacing between bunds. The spacing between two contour bunds depends on the slope, the area and the permeability of the soil: the lower the permeability of the soil, the closer the bunds should be. Contour bunding is suitable on land with moderate slopes, without terracing.
Gabion structure method
A gabion is a kind of check dam commonly built across small streams to conserve stream flow with practically no submergence beyond the stream course. A small bund across the stream is made by putting locally available boulders in a mesh of steel wire, anchored to the stream banks.
Such structures are about 0.5 m high and are normally used in streams less than 10 m wide. Excess water flows over the structure, while some water is stored to serve as a source of recharge. Over time, silt in the stream water settles in the gaps between the boulders. As vegetation grows, the bund becomes almost watertight and holds surface runoff long enough after the rains to recharge the groundwater.
Percolation tank method
A percolation tank is an artificially created surface water body that submerges highly permeable land, so that surface runoff percolates into the ground and recharges groundwater storage. Percolation tanks should preferably be built on second- to third-order streams, located on highly fractured and weathered rocks that continue sideways downstream. The recharge area downstream should have enough wells and farmland to benefit from the extra groundwater.
The size of a percolation tank should be governed by how fast water soaks through the tank bed. Percolation tanks are normally designed for a storage capacity of 0.1 to 0.5 million cubic metres (MCM), with a water depth generally between 3 and 4.5 m.
Most percolation tanks are earthen dams, with masonry only for the spillway. Since their purpose is to recharge groundwater, seepage below the base of the dam is acceptable. For dams up to 4.5 m high, cut-off trenches are not needed; keying and benching between the dam base and the natural ground are enough.
Check dams, cement plugs and nala bunds
Check dams are built across small streams with gentle slopes. The site should have a thick enough permeable bed or weathered layer so that stored water recharges the ground within a short time.
The water stored in these structures mostly stays within the stream course. Their height is normally less than 2 m, and excess water flows over the wall. To prevent scouring from excess runoff, water cushions are provided on the downstream side.
To capture the most runoff in a stream, a series of check dams can be built to recharge a whole region, as Kalyaan has proposed for the Jawai River in Jalore and as villagers achieved with check dams in Dholpur. Clay-filled cement bags stacked as a wall are also used successfully as barriers across small nalas. In some places a shallow trench is dug across the nala and lined on both sides with sheets, and the space between them is filled with clay, creating a low-cost check dam. Clay-filled cement bags stacked in a slope on the upstream side give the structure stability.
Recharge shaft method
Recharge shafts may be dug by hand if the ground does not cave in. The diameter of the shaft is normally more than 2 metres. The shaft should end in a more permeable layer below the top impermeable layer, but it need not touch the water table.
An unlined shaft should be backfilled, first with boulders and cobbles, then with gravel and coarse sand. In a lined shaft, recharge water may be fed through a smaller pipe reaching down to the filter pack. These structures are very useful for village ponds where a shallow clay layer stops water from soaking into the aquifer.
In the rainy season, village tanks often fill up, but the water does not percolate into the ground because of silt, and nearby tube wells and dug wells stay dry. The water in the tanks evaporates and is lost.
By building recharge shafts in such tanks, surplus water can be sent into the ground. Recharge shafts 0.5 to 3 m in diameter and 10 to 15 m deep are built, depending on how much water is available in the rainy season. The top of the shaft is kept above the tank bed, preferably at half the full supply level, and the shaft is backfilled with boulders, gravel and coarse sand.
The top 1 to 2 metres are lined with brick masonry for stability. With this technique, all the water in the tank above 50% of full supply level is recharged to groundwater, while enough water stays in the tank for household use.
Dug well recharge method
Existing and abandoned dug wells can be used as recharge structures after cleaning and desilting. The recharge water is led through a pipe from a desilting chamber to the bottom of the well, or below the water level, to avoid scouring the bottom and trapping air bubbles in the aquifer.
Recharge water should be free of silt, so runoff should first pass through a desilting chamber or filter chamber. Periodic chlorination should be done to control bacterial contamination.
Groundwater dams or subsurface dykes
A subsurface dyke, or underground dam, is a barrier below the ground across a stream. It slows the underground flow and stores water upstream below the surface. As a result, the water level upstream of the dam rises, filling the otherwise dry part of the aquifer.
The site for a subsurface dyke should have a shallow impermeable layer, with a wide valley and a narrow outlet. Once a suitable site is chosen, a trench 1 to 2 m wide is dug across the stream down to the impermeable bed. The trench is filled with clay or a brick or concrete wall up to 0.5 m below ground level.
To make it fully watertight, PVC sheets of 3,000 PSI tearing strength at 400 to 600 gauge, or low-density polythene film of 200 gauge, can be used to cover the faces of the dyke. Because the water is stored within the aquifer, no land is submerged and the land above can still be used after the dam is built. There is no evaporation loss and no silting of the reservoir, and the danger of a dam collapse is avoided.
Cities can catch rain on a large scale too: Singapore’s water management collects rain from two-thirds of its land.
Sources
- Vikaspedia (Government of India), pages on rainwater harvesting and groundwater recharge, based on Central Ground Water Board guidance, vikaspedia.in, accessed 9 November 2026.
Questions and answers
What is the best rainwater harvesting method for villages?
It depends on the land. On hill slopes, gully plugs and contour bunds work well; on small streams, gabions and check dams; near village tanks, recharge shafts; and in valleys with a narrow outlet, underground dams.
What is a percolation tank?
A percolation tank is a man-made pond built on permeable land so that runoff soaks into the ground and recharges groundwater. Most are earthen dams storing 0.1 to 0.5 million cubic metres.
Can old dug wells be used to recharge groundwater?
Yes. Existing or abandoned dug wells can be cleaned and fed with silt-free rainwater through a pipe from a desilting or filter chamber, with periodic chlorination for safety.
What is a subsurface dyke or groundwater dam?
It is an underground barrier across a stream, built down to the impermeable layer, that holds water inside the ground. Land above stays usable and no water is lost to evaporation.
