Rain Water harvesting. Which is the better method?

[bkvenu]

Hello,
We are constructing a house on 30x40 site and have a borewell which is 350ft depth and it has yield 2.5” of water. As a general practice we are going on for Rain water harvesting.
RWH techniques which commonly carried are
1) Dumping all the rain water into borewell pit
2) Storing the rainwater in a sump for further use and diverting the excess water into the pit.
Which of these two methods provides better maximum utilization of rain water?
Suppose if I want to go with method 2, what are the extra procedures (other than sump and overhead tank as it will done as usual) we need to follow compare to 1.
Our construction status is still in foundation, is it the right time to plan on this or I can wait till completion of the structure?

Regards,
Venu

[msn1270]

Going for the later option is good. Where you can use the rainwater to some extent and also control the flow of water to drain to the earth.

You should not directly pass the excess water to the Borewell Pit. This method is followed only in case of the Open wells. Here you need to make separate pit arrangement for excess Water to drain into the earth at a distance from your borewell. Else it will increase the stilt at the bottom of the borewell pit over a short period and, it harms your pump.

[nesaraRWH]

hello bkvenu,
since your's is a 30x40 site with terrace area of around 1000 sft, you can harvest the rainwater from rooftop, after good filteration directly into borewell casing pipe for recharging, this will benefit directly in reducing the hardness of ground water and also helps in retaining ground water table, OR the best option is to allow the filtered rain into sump tank and the excess rainfall overflowing the sump can be connected to borewell casing for maximum utilization,
required sump capacity is 6000 lts to 7000 lts.
regards
vivek

[waxwing]

I would agree with Vivek on the option of using the filtered rain water into the sump and the excess can be sent as an overflow which can then recharge the ground water. There are many filters available ( eg Pop up filter costing around Rs2500) and can be used for filteration. Since i work in an organisation, working on rainwater harvest and related things..i would suggest you go for a small partition similar to a baffle in the sump and let the rainwater alone into it ( this tank can be of 3000 Litre or so) and use the rest of the sump ( 7000 ltr capacity) for normal cauvery water ( if available in your area). This rainwater can be utilised for secondary purposes like flushing, car wash and gardeninng purpose. For toilet flushing, u need to have a separate pumping ( 0.5 HP motor) and piping arrangements to a separate tank, which will send water only to toilets....This way u are utilising the rainwater to the maximum usage...During the summer months, the same tank can be utilised for storing normal water by having an interconnect at the top end of the baffle wall inside the sump. The excess water can be utilised for groundwater recharge system. This can be done by simply placing two 300 litre plastic drums ( both sides open) one on top of another ( 6ft height) at a suitable location inside the earth....Ideally the recharge systems should be near the borewell ( say 10 feet from the borewell depending on soil conditions. Since your house is in construction stage, u can design it easily as per your requirement. Believe....it does save a lot on the long run....but still u need to go for little investment now....Best of luck....do contact me at waxwing@rediffmail.com if required...

[sri_bangalore]

Hi Vivek,
How do i reach you? I need some help in this as well.

Regards,
Sripathi

[krish]

Hi Vivek,
How do i reach you? I need some help in this as well.

Regards,
Sripathi

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[sam_m400]

I have one question. In the forum it is mentioned that instead of having pit around the Borewell we could directly connect a filter at roof top and filtered water can be connected to borewell casing pipe. But what about overflowing of borewell ? . If my depth is 480 feet ,and i am filtering 5000 literes of water direclty to the casing pipe what will happen if it overflows...............

[m3_07]

But what about overflowing of borewell ? . If my depth is 480 feet ,and i am filtering 5000 literes of water direclty to the casing pipe what will happen if it overflows

This is a very unlikelly scenario that the well overflows. In all probabilities, the water gets distributed to other wells. Your well acts as a donor well. There is a well on the banks of cauvery, which "actually" overflows. The bore is a sight to see when the ground tables are very good. This however is not the case in any of the wells in bangalore.

I have a very basic question about RwH....we actually should call it plain water harvesting rather than rain water harvesting. What if we do not have rains for the whole year???? should the wells go bust???? There actually should be a way/ process where the water utilized from the well should be sent back indirectly through layers of filtering. This is water harvesting & we do not end up blaming the rain gods for inadequate/ rather no rains!!

[sam_m400]

@MSN
" Here you need to make separate pit arrangement for excess Water to drain into the earth at a distance from your borewell. Else it will increase the stilt at the bottom of the borewell pit over a short period and, it harms your pump."

i saw your comments ,and that is same issue i heard recently while about to start digging borewell pit.Any clue how much distance i should move the pit away from the borewell casing.

[SAMPATH S]

Dear Rainwater Harvesting enthusiasts – Your search for a most effective, efficient, low-cost and do-it-yourself rainwater harvesting filter for storage ends here – Please refer to the new thread started by me:
http://www.mybdasites.com/viewtopic.php?f=98&t=9369&p=46013#p46013