RWH in a layout: getting started

Step 2 – What should be the RWH strategy for your layout

Another factor to consider when determining the best RWH interventions for your context is your layout’s land use pattern. In a typical urban residential layout, land use is usually as follows: approximately 60% is rooftops, 20% is roads and the rest is open-areas like parks, playgrounds, footpaths, transformer yards or drains.

This means that the largest amount of rain is falling on rooftops. Rooftops are also clean and so rainwater running off of them is clean. It is prudent to try and capture this at the household level and use it for domestic purposes, which will reduce dependence on other water sources during the rainy seasons. It is possible in most cases to retrofit households with RWH systems, though it is worth noting to those building a new home that the cost of domestic RWH systems is significantly lower when RWH is incorporated into a new home design.

Investment in domestic RWH is done at the individual household level. The harvested water can be stored in an existing sump, in a new storage tank or for recharge. Water stored in tanks can be used for all domestic purposes, though certain precautions and treatment is necessary if it is to be used for drinking and cooking (more about this in later parts of this series). Click here for information on the components and benefits of a domestic RWH system with storage tank, and here for background on RWH using an existing sump as storage.

Recharge well in stormdrain

Recharge well in stormdrain. Pic: Rainwater Club.

As for the 40% of rainfall not falling on rooftops, recharge wells are a valuable intervention to consider, as they can replenish the ground water supplying your layout’s borewells, and can also help with flood management. Recharge wells can be developed to collect run-off from common areas such as roads, parks, and storm drains. These investments will need to be made collectively. S. Vishwanath posted an informative recharge well video on YouTube.

Finally, one must consider the residents themselves and which interventions they may or may not support and why. Cost, upkeep and aesthetics are three key factors in people’s decisions to support or oppose a particular intervention.

One will usually not find the answers to these questions until they start asking.

Rainwater Club
rainwaterclub [at] gmail [dot] com

1022, 1st Floor, 6th Block, HMT Layout
Vidyaranyapura Main Road,
Vidyaranyapura,
Bangalore – 560 097
Office – 80416-72790
www.rainwaterclub.org

Step 3 – Talk to an expert

Consulting someone with technical RWH expertise can further clarify the most appropriate interventions for your layout and supply you with helpful information to share with other residents. Some source of good technical input and expertise can also assist with strategising, design and implementation. This can be sourced through the market from service providers, NGOs, individuals with expertise or others who have already done it.

A note of caution: RWH design is a deceptively complex science, and it is important you make sure the expert you consult understands the fundamentals. Our advice is to confirm that your expert has experience designing and implementing RWH. Ask for their track record of successful installations.

Then what?

Once you have an idea of what interventions you would like to pursue in your layout, you must enter a process of engagement with other layout residents to address various concerns and achieve clarity on all the benefits. How this process can be achieved will be covered in the Part 2 of this series.

Coming next

Part 2: Engaging with the people of the layout.
Part 3: Understanding the technology of storage and recharge – a FAQ on household RWH
Part 4: Creating an environment that incentivises RWH.

Addendum

About recharge wells and pits

1. What is a recharge pit? Is it the same as a recharge well?

A recharge pit is a hole dug in the ground. Usually it is filled with gravel or jelly to give it structural strength. A recharge well is not filled with gravel. It needs concrete rings installed in it to stabilise its walls.

2. What should be the depth of a recharge well/pit?

If you want to have effective recharge for Bangalore conditions, a 15-20 feet depth is needed. (Provided you do not hit rock before that depth). If you hit water while digging the pit, you need to ask the workers to be careful while they continue digging. The diameter of the pit you choose depends on two things: space available and the quantity of water you will send in.  A 3 feet dia X 20 feet pit will ‘hold’ around 4000 litres (for recharging the ground). A 5 feet x 30 feet structure can hold 16000 litres.

3. What are the legal guidelines and their implication for recharge pit sizes?

The law states that you need to store or recharge 20 litres for for every sq.m of roof area and 10 litres for every sq.m of non-roof (ground surfaces such as parking, backyard) area. This is for plot sizes of 40×60 or more.  For e.g. if your home has about 100 sq.ms of roof area, and about 50 sq.ms of non-roof area, then you will need to create capacity for at least 2500 litres of  water. If you are using a 1000 litre tank to store rainwater for immediate use, you can connect the overflow to a 4000 litre (3 feet x 20 feet) recharge well.

4. How much do recharge pits cost?

Cost of digging a 3 feet diameter x 20 feet deep well is approximately Rs 20,000.

Avinash Krishnamurthy is a member of Rainwater Club.

2 Comments

  1. Dear all,
    We would like to clarify regarding the complaint against the company.Based on the customers request, the installation was done by giving the roof top water to Borewell by a filter which filters up to 250 microns.We have carried out this process from past 3 yrs and done 1000’s of Installation with this process. We never had complaint. In fact even dried bore wells have rejenuvated & quality has improved. Since only roof top water has been given through filter, there are no chances that the motor being damaged due to this process. The submersible motor name itself indicates that it is already submerged in water and will not be affected by addition of the filtered rain water. As per the information provided by the customer, the bore well is around 15 years old and this might be a mere coincidence for the motor to stop working after the installation.
    The customer requested for a Re-charge pit later n we called on few people who take up this task and directed them to customer. On further conversations the customer agreed to pay for materials and we took up labor expenses on compassionate basis. The customer never called back, but instead had filed a complaint in the BWSSB Office.
    The claims made by the customer for paying Rs.20,000/ for the installation and a 5 year warranty are not true. The actual payment made is Rs.16,000/- and the warranty being for a period of 1 year.
    We had enclosed a copy of the bill and receipts of payments received from the customer and a copy of the warranty card which is normally given with the system to the customer and submitted to the Chairman & the concerned Engineer on August 4th 2010. A copy of the endorsement was also attached for kind reference and submitted again on 08-10-2010.
    Considering these facts, further claims made by the customer might not be true.
    We hope our clarifications are upto the satisfactory level.

    Regards
    For Aditya rain water harvesters
    Anand
    9880660701

  2. I took your reference from BWSSB site and engaged Aditya Rain Water Harvesters, 1st main, Uday nagar, Bangalore, to install RWH in my house. His mobile number is ‘9880660701’.

    Since the company was referenced by BWSSB website and I engaged him to do the RWH for Rs 20000 with their claimed advanced system of recharging borewell directly.

    I paid entire amount upon agreeing for 5 year warranty. Within two rains my entire borewell was shut and my submerged motor is gone bad due to this system. Now my entire water flow to my home is gone and I have to spend at least another 50000 to get it right. I blame BWSSB to keep these fraudsters in their recommended list.

    I made at least 150 calls and multiple emails, SMSs to get help from this guy. anand refused to answer the phone the moment they realized the problem of their system. I want to advertise on this extensively so that I can save others from not going through his system.

    These folks are bringing disrepute to BWSSB and average citizens are suffering due this cheating. You have to black list these fraudsters and help law abiding citizens to believe in BWSSB reference.

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