All you needed to know to make a recharge well

1. Recharge Well Diagram with details Rainwater Harvesting Guide
RECHARGE WELL
Do-It-Yourself
31st December 2011 is the deadline for Rain Water Harvesting
implementation as per BWSSB regulations.
Did you know? Rules:
Storage/Recharge recommended by BWSSB per sq. mt. of roof area is
This activity (of digging Recharge wells) is providing 20 litres and for paved area is 10 litres.
employment to the Bovi community - the traditional
well diggers
How much will it cost
3 feet diameter and
20 feet deep well
4 feet diameter and
25 feet deep well
5 feet diameter and
30 feet deep well
What does this cost include?
Digging labour
Rings - procurement + transportation
40mm jelly - placed in annular gap between pit and rings
Concrete slab/metal grille - with manhole for maintenance Sir Vishweshwaraiah Rainwater Harvesting Park
Dumping of excavated soil - (this can be very expensive in 8th Main, 40th Cross,
certain parts of Blr !!) 5th Block, Jayanagar, Bangalore.

2. Why should I do ground water recharge? How do shallow acquifers form?
There are cases where locally there will be a layer below the open
5 6
Bangalore is growing at an unprecedented rate, and its sprawling well in the sponge where water from the recharge well does not go
expansion outpaces the public utility’s ability to accommodate into the sponge itself. Instead it builds an underground lake and that
skyrocketing demand for water and sanitation services. It is becomes the shallow acquifer. The recharge well then starts yielding.
increasingly common for new residential communities to assume total
management for their own water and sanitation services through their Over a very long time, deep acquifers can get saturated too, and this
resident welfare associations. Most of these depend on borewells and can build a shallow acquifer above. As more and more water is
tankers, which they sooner or later realize is not a sustainable option. continually drawn from the acquifers, yields (for borewells or open
Groundwater recharge, one of the forms of Rainwater harvesting, can wells) tends to fall off over time, unless recharging is being done.
be instrumental in efforts to achieve long-term water security. By Place all the rings and center them Complete the well by packing Jelly
taking water out of over-stressed storm drains and replenishing them Did you know? all around the RCC rings
into shallow aquifers, groundwater recharge wells effectively raise Residents who have done continuous recharge for a
water tables and reduce the intensity of flooding in a layout. period of 2-3 years have revived wells now that yield 7 8
water all through the year. These houses can do
without corporation water supply.
The making of a Recharge Well
A Recharge Well can be easily constructed using concrete rings
of diameter ranging from 2 feet to 6 feet and depth of 20 feet to 30 feet
to store large volumes of rainwater and recharge the groundwater under
Place a strong perforated RCC For large quantities of water
good hydrostatic pressure. About 70% of the water will percolate
cover or a grill for safety. The (industries, layouts...), a Percolation
vertically, the other 30 % horizontally through the holes provided in the
water should be filtered to remove test should be done with the first
rings. The soil profile of the site helps to determine the depth of the well,
the silt and leaves before it enters well, to see how fast the water
its bottom should reach a critical level of the weathered zone, where the
the well through an internal pipe. enters into the ground, and thus the
water can easily percolate.
number of wells necessary can be
1 2 known.
The diagram above explains Bangalore’s geology- below the top soil
is the weathered zone, which is made of rock and behaves like a How can I clean/ filter the water before
sponge. This layer changes from area to area. Then comes the bed sending it to the Recharge Well?
rock layer. The bed rock is not a monolithic layer; the rocks have
cracks and fissures through which water passes and gets Identify the catchment area and ensure that it is clean and
accumulated inside the rock. This is a deep acquifer. Borewells break unpolluted, make sure there is no sewage close by. Especially
into the bed rock and taps into the water there. when water is picked up from lawns it should be free from
fertilizer and pesticide. The golden rule for recharge is put in only
What is recharging? Excavation: Dig a well having Lower the RCC rings one by one what you can take out and drink.
Recharging is process of letting water back into the earth. A recharge dimension 2” more in diameter, into the well . Place the rings
well is a big hole through which water goes into the sponge or than the RCC rings one above the other. The rooftop rainwater,
weathered zone. Recharge wells are dry wells, in the sense that they water runoff from the
send water down in one direction, and do not yield water (initially at 3 4 storm drains is filtered by
least) themselves. placing a slab and leading
the water into a pipe
Will I get this water back? which has been covered
Imagine a dry sponge and you are pouring water through a hole into with mesh and jelly to
the sponge. The water soaks up the sponge. Sooner or later, the purify the water.
sponge will hit a saturation point. At that point water appears back
in the recharge well and it starts yielding. When this happens (all
recharge wells have this potential) a recharge well becomes an open Is it safe to dig a well in a Residential Area?
well. The Jelly is then lowered into 40 mm Jelly
the well and packed between
the rings and the well to
ensure the rings are in place