capacity for the storage of harvested rain water

[Dr S B Katoley]

Now a days in all projects it is mandatory to implement rain water harvesting, which is either used for ground water recharge or has to stored if the water table is sufficiently high like in coastal areas.There are no guidelines on how much storage capacity should be provided for the harvested rain water. However, the environment appraisal committees are generally suggesting storing the two day fresh water requirement of the project. This is not only expensive but some times requires a very large area for constructing the storage water tanks.Besides, the setting up of a STP is also a requirement for the project with a condition that the treated waste water will be used for flushing and other non potable purposes. If the treated waste water is available for use the daily water requirement is reduced and therefore storage of two day's requirement of fresh water harvested through RWH may not be necessary. This has other ramification like the calculation of water budget based on 135 lpd or 90 lpd depending on the availability of water.

The moot point is therefore how much storage capacity should be installed for the RWH.

Any expert, who is conversant with the issue, may like throw light on this important aspect as it is linked with the feasibility and cost of project.  

[Mrs. Lata Jha]

Collecting handful of rooftop rain water and storing it in tanks is not a solution until we do something to raise the Ground Water Table, especially around the boring. We provide such solutions which does not require surface land neither any tank which are difficult to maintain and does not serves the purpose of portable water. Our system is built under the ground and it recharges 80% of RW of the catchment area. Zero maintenance, gives water security for lifetime and for generations to come. This can be a good quality of portable water if there is no source of effluents nearby. Its a low cost system, can be installed effectively at the time planning a project. 

[DAA]

would like to know teh std. format of water budget, if RWH provided

[Sarika Baheti]

www.vectus.in

[Sarika Baheti]

https://www.facebook.com/KediaRainwaterHarvestingPvtLtd?ref=br_tf

[Krupali VIjaykar]

Hello,

After reading all the posts, I wanted to clarify the RW harvesting issue as far as the Green buildings is concerned. Though it is a mandatory requirement, storing of RW is not mandatory. When we talk about RW harvesting, we go by storage or recharge approach. 

The second approach- i.e. Recharge of RW is the most sane way & it helps in increasing the water table.

We normally have pipes that through which the rainwater from the terrace flows down. The same one, if penetrates the ground, can act as a RWH system.

[Vivek Kulkarni]

Dear Dr. Katoley,

You have raised a valid point here. I would like to get little bolder and would like to ask if RWH is at all required in such areas?

One must consider that rain water is seasonal. You may construct large tanks to harvest water only for three months. During dry months, these tanks are useless. Contamination of tanks and repairs of tanks is another issue. Builders may construct these tanks and go. Can Societies afford to run them? You cannot use this water for drinking purpose unless you give tertiary treatment. This would be additional expense. If all these costs constantly rise, why would people go for such practices.  

Technology and solutions for environmental betterment should be affordable and easy for their acceptance in the society.

Regards,

Vivek Kulkarni

[Chingsubam Matouleibi Devi]

Yes Sir, you have rightly pointed out that there is no guidelines specifying on how much water to be harvested. I would like to suggest that project must harvest 100% of roof run off since the water is cleaner comparatively and no expensive treatment may require. Construction of tank is suggested if intention is to reuse the harvested water though it is quite expensive at initial stage, however, it will provide solutions during water shortage. If construction of tank is not in domain, then recharging must be followed on site as it has positive effects overall.

To clarify on your query for reusing flushing water and collecting RW, water quality for treated water and rain water are different. Treated water can be reused only for non potable purposes like landscaping, flushing or to some ancillary activity for an extent. It cannot be used for activities which will come in direct contact with body even though it has been claimed that it can be used for drinking after advanced tertiary treatment. But harvested rain water can be reused for washing clothes, internal floor cleaning, even in loo. As you are aware, rain water is the only source of water for daily in different parts of the world. Hence, storing rain water is always good.

About the amount of water to be collected, Under IGBC Green Building guidelines, the minimum mandatory rain water to be harvested for whole site is 25% of total volume of runoff. Untill and unless, project is harvesting 25%, the project will not be certified as Green Building. You shall download the guidelines from IGBC websites.

Kindly details on what is the difficulty while calculating water budget. We shall have a discussion on the query.

Regards,

Matouleibi