As soon as you enter the house, you will see the office to your left. All the pamphlets, material, contact info and other materials of relevance can be found on the shelves in the living room (see photo). The kitchen further ahead (see photo) has a 24 hour water supply. There is one tap in the kitchen attached to metro water from the city and the other tap attached to the overhead tank which is replenished with water collected from the rain water sump. We do not rely on the metro water supply for the water needs of the rain centre.
The two bathrooms attached to the two bedrooms also have water supply from the rain water collected in the overhead tank. (see photo).
The bedroom adjacent to the living room has been converted to a water testing laboratory. Rain water collected at the rain centre RWH installation can be tested for its purity. Also, the rain water collection statistics are displayed in the graph attached to the meter. See schematic of plot.
| Plot size: | 40' x 60' (1 ground) - 2400 sq. ft. |
| Plinth area: | 30' x 40' - 1200 sq. ft. |
| Total roof area for rain water harvesting: | 1000 sq. ft. |
| Total ground area for rain water harvesting: | 1000 sq. ft. |
There are two primary types of rain water structures installed at the rain center:
Roof rain water harvesting structure:
The schematic below shows the roof rain water harvesting structure. Rain water is collected from the roof and flows through the drain pipes to a filter below. The roof has a gradual slope to direct the rain water towards the drain pipes see photo). At the rain center, the drain pipes are 100 mm wide PVC pipes (see photo) whose average life is expected to be around 10 years. People have also used cast iron pipes as drain pipes. The choice purely depends on the individual's preference and cost. The drain pipes are covered with a drain cover (see photo). The drain cover lets water flow into the drain pipe while holding back the leaves, stones, and other garbage which can clog the drain pipe. Once in two years it is a good idea to clean the drain pipes to ensure free flow of water.
When the rainy season begins, the initial water that pours through the drain pipes is not saved. Instead it is discarded as "first flush" (see photo). This water theoretically just cleans the drain pipes of dust, leaves, and other garbage collected over the rest of the year. Once the first flush is cleared, the rest of the water flows through a filter (see photo) into the well at the site. A total of four drain pipes drain into the filter. The dimension of the filter is as follows:
The bottom of the filter is filled with 4 feet of pebbles followed by coarse sand upto 4 ft. The schematic is shown below. The filter can also be made of sponge, but the sand and pebble arrangement is more economical. If water does not flow freely through the filter and starts clogging the filter, then the filter will need cleaning. Cleaning involves removing the sand and the pebbles from the filter and putting them back since over time the dust and particles from the rain water can clog the pores in the sand and pebbles. The maintenance is needed once every 10 years or so and costs about Rs. 200/-
The water thus filtered is sent to the well attached to the rain center
(see photo). When required, the water is pumped (see photo) to an overhead tank
(see photo) located on top of the house.
Surface rain harvesting structure:
The surface runoff at the rain center is collected from the pavement that
goes from the portico to the fence and all the garden area. The percolation
slab (see photo) shown in the schematic helps direct the surface rain water
into the filter below. The filtered water is then redirected into the aquifer
that recharges the well attached to the house. The filter pit below is 3' in
radius and is filled with stones, pebbles, and gravel. The percolation slab
itself is made of cast iron. There are three percolation slabs at the rain
center - one in front of the house along the pavement, one is garden behind the
house, and the other to the side of the house.
The location of surface run off percolation slabs will depend on the layout
and construction around your site. Please contact a rain water harvesting
certified contractor for help on how and where to install these surface
structures.
The following table summarizes that cost of installing the rain water harvesting structures at the rain center. To calculate the cost to install rain water harvesting structures at your plot, please download our calculator and use that as reference. Also, contact a certified local contractor to get a more accurate estimate.
| Item | Cost |
| Roof Rain Water Harvesting Structure | |
| Pipes (100 mm PVC) | Rs. 1000 |
| Drain Covers | Rs. 100 |
| Filter Pit | Rs. 500 |
| Pump for O. H. Tank | Rs. 2500 |
| Labor | Rs. 2000 |
| Total | Rs. 6100 |
| Surface Rain Water Harvesting Structure | |
| Percolation Slabs | Rs. 600 |
| Filter Pit | Rs. 500 |
| Total | Rs. 1100 |
These are estimates. Actuals may vary based on individual needs.
The amount of rain water collected is being monitored daily since installation of the rain water harvesting structures. The graph below shows actual rainfall in the area with time and the amount of water collected from the rain water structures at the site (see graph below).
Both the ground water level and water quality is being monitored daily since inception of these structures at the rain center. An analysis of the data reveals that ground water level has appreciated since the structures have been installed. It is anticipated that the ground water level will saturate at a level that makes the rain center self sufficient for its water needs. Similarly, the quality of water is graphically compared with the water that metro water supplies. Mean value of total dissolved solids in the roof water is 20.5 mg/l. Bacteriologically, it is free and is harmless. Average value of turbidity in pond water is 58.68 JTU against a permissible value of 10 JTU for drinking purposes whereas the water from the roof water is clean with 1 JTU. It should be noted that rain water is naturally clean due to its evaporation and then precipitation. The water is also very soft and lathers well for washing.