Rain water harvesting in a leafy London suburb

If its London, it must be raining ! This is the common thought that runs through most people's minds, so then where does the question of rain water harvesting arise?  Rainwater harvesting for me a journalist out of India is meant for countries with fresh water scarcity issues. Obviously that was an ignorant supposition as wasting of valuable rain water can happen anywhere in the world.  

Chatting with a London resident who lives in the leafy  London suburb of Woking, one finds that a system of 'harvesting' the rain has existed for decades here in London and he took me around his 100 year old home in Woking to explain the system.

"In Woking there is a system called a  soakaway where building regulations require you to adequately dispose of stormwater from the building. To try and ensure water is dispersed into the ground evenly and quickly you must consider the use of a soakaway in all homes, according to the council," explains David.

" You must use a soakaway, if design criteria can be met. Discharging stormwater into a drain will only be allowed if soakaways or other infiltration into the soil, methods are not suitable," said David.

So we were curious to know how  do soakaways work? Soakaways store the immediate stormwater run-off to allow infiltration into the adjacent soil. Then, they  must discharge their stored water sufficiently quickly, to provide the necessary capacity to receive run-off from a subsequent storm. The time taken for discharge depends upon the soakaway shape and size and the surrounding soil's capacity to absorb. Soakaways can be constructed in many different forms and from a range of materials .

Interestingly one cannot just build a soakaway without first checking if a soakaway is the most suitable means of disposing of stormwater. That is done by checking if the soil around the building can absorb water; the site is not on filled ground; the site does not slope towards the building and; the water table is not too high already. Other rules are that  soakaways can be sited at least 5m from any buildings and if one is close to boundaries the neighbour should be consulted.

The council gives guidelines which are interesting to read up on, regarding the building of the Soakaway In most cases where the soil drains well, and the roof area is less than 100m2, you will be able to construct an open chamber type soakaway, as follows:

Calculate the roof area to be drained into each soakaway. Then calculate the volume of the soakaway:

Roof area in m2 divided by 40 = Volume of soakaway in m3 (AxBxC)
The volume can then be measured below the incoming pipe and above top of foundation.

The council is particular that the  residents ask for an inspection of the drainage and the soakaway while it is being constructed.

David's soakaway was in the middle of his lawn! Well, if this can be done in London, why ever not elsewhere right?

Marianne de Nazareth

Alliance for the Rain Movement

“Success will be bigger if we work together”, said Vessela Monta, executive director to International Rainwater Harvesting Alliance (IRHA), at a meeting held on 28 November 2013. Representatives of different organizations with a sole motive to establish Nepal Rainwater Harvesting Alliance (NeRHA) were present in the meeting. The alliance aims to suppress the feeling of competition among those participating organizations and bring them together for better outcomes in Rainwater Harvesting aspects of Nepal.

As the alliance is in starting phase, agendas on network criteria and necessities were discussed and prioritized. After the discussion among the participants, a scoping team of 5 members has been formed. Meeting to be held once in every two months is also decided and agreed. The profiling of all the activities related to rainwater harvesting practices by the member organizations was decided by the meeting. Along with this advocacy through newsletters and information dissemination in the website will be initiated. 

As it is going to take time for binding and shaping up the other functions of the alliance, Lumanti will act as Secretariat of the alliance until the alliance is registered according to the NGO’s rules and regulations of Nepal. 

Government shall be invited as an advisor rather than being involved in the networking aspect of the alliance. The meeting adjourned to be held on 31 January 2014 and a work plan shall be discussed next. 

By Bimala Gurung

Harvesting Rain for Terrace Farming

With the growing consensus among the city dwellers about the organic farming on the rooftop recently an exhibition for the promotion of terrace farming was held as a possible alternative way to maintain greenery, manage the solid waste and good security by the Kathmandu Metropolitan City.

Inaugurating the event Deputy Minister Prakash Man Singh advocated in favor of providing environment for the further promotion of terrace farming. The exhibition showcased different technologies for recycling, waste treatment, irrigation, organic farming along with the low cost water harvesting technology for sustaining farming practices.

With the concept of utilizing rainwater for terrace farming and other household purposes a model of Rainwater Harvesting system along with the treatment system and reuse of wastewater was demonstrated by Niva Rain in collaboration with Guthi, a member of Nepal Rainwater Harvesting Alliance (NeRHA). Visitors who were positive regarding the framing practice became even more enthusiastic when they were introduced with the rainwater harvesting system as it seems promising in delivering rainwater to fulfill their greenery mission.

Rainwater harvesting demonstration presented complete solution for the collection, storage, purification and reclamation of water for the mass of people who were still in confusion regarding the installation of system. The reclamation of water through constructed wetland along with the purification of water through Bio-sand filter provided answer to the queries of visitors who believed harvesting is for temporary only. Further limelight to the exhibition stall was added by Narendra Man Dongol who himself has installed the system and has been living on rainwater. His daily water demand and yearly saving on water was even more exemplary for the visitors.

With the water demand of 1200 liters per day, supplied through reclaimed water, 700 liters and rest 500 liters from the rainwater he has been able to save Rs.5000 per month. Amazed with the figures Niraj Dongol one of the visitors said that “dream of Kathmandu city as sustaining eco city seems to be possible, when every drops of rain are used in blooming every seeds through harvesting practice.”

The stall not only grabbed the attention through cost effective technologies but also introduced portable sack tank commercially known as ‘BOB’. The sack tank is easy to transport and weighs only 3.5kgs when empty. It can fit into an airline hand carry bag when folded and despite its size; it has a capacity to hold 1400 liters of water. The outer bag of sack tank is UV resistant woven polypropylene and the liner is 100% virgin polyethylene- a material that is approved for contact with food. The cost of this tank is NPR 5 per liter. While comparing this with the Reinforcement Concrete (RCC) tank that costs NPR 30 per liter and PVC black tank that costs NPR 11 per liter.

For the tenants who could not harvest their share of rainwater due to lack of space now can claim their share of water, informed Prakash Amatya, a member of NeRHA. For those who depend on still water of dug well, can now enjoy the fresh shower through harvesting of rainwater. Since this bag is portable, it could be used in monsoon months only and wrapped up for the rest of the season.

Excited with this new innovation Purna Limbu said, “Rainwater harvesting has always been alternative for the water crisis but this water bag has been alternative to the space crisis also, now everyone can have easy access to rain water”

Really, rainwater has been boon to the existence of living organisms, needless to say what its importance is in our daily life however, at the recent time when the world is facing serious water woes rainwater harvesting plays a vital role in reducing extraction of ground water to increment in ground water table. Considering this utility of rainwater we need to harvest  every single drop of water not only harvest rather also reclaim it so we could fully trust on rainwater, which  is not so herculean task just the right blend of available technology. If Narendra can depend on rainwater through this technology then why can’t we?

By Neha Basnet

Aalkohiti blesses no more!!

A stone spout once a model of conservation to many other stone spout and community initiatives is now looking for more efficient system that would revive it. Aalkohiti is dying, having the history of more than 1600 years, Aalkohiti has seen many prosperous and adverse years, and at times it gave life- water to majority of residents near it but now with starting of dry season the hiti itself is dying. Like all other hitis of Kathmandu this historic stone spout was counting its days to extinct however people from the surrounding community gave it life by ensuring continuous recharge of water to flow via Rainwater Harvesting, and gave it a modern twist by supplying water to 200 household ensuring the accountability of the water users to conserve the stone spout.

Aalkohiti

pond next to aalkohiti at present

Supported by various organizations, Aalkohiti conservation was initiated by the locals giving it life. Once people discovered the water in the hiti comes only if ground water is recharged, people concluded in artificially recharging groundwater by collecting rainwater of the 300m long pavement. “Two recharge structures were constructed, but at the moment one has been buried as it is no longer recharging while we are also facing problems in recharging via remaining recharging well, resulting in lesser recharge of rainwater,” shared Mr. Sushil Shrestha, a pioneer in conservation of Aalkohiti.

For more than a decade the recharge structure served to conserve Aalkohiti and supply water to more than 200 families in the locality through pipelines and hundreds of other families who collected water without any hindrance except in the dry season. “It was routine that Aalkohiti would dry during the dry season almost for two months, but this year the hiti has dried a month earlier probing acute shortage of water in the locality,” said Anil Shrestha a local resident.

While it is obvious that water source would dry up during the dry season, this time rise in temperature has played its significant role, meanwhile the less recharge of the water during rainy season is another reason that Aalkohiti is not serving people a month earlier than its usual routine. “The situation is being routine these years as we have buried one recharge structure and water recharging has slowed sown in another recharging well,” analysed Mr. Sushil. According to him the recharge well are being jammed with the mud from around the well and blocking the passage of the water as it has closed the pores of the gravel, resulting in less recharge. It is vital that we check and maintain our recharging system and also look for more efficient way to recharge, he added.

The in depth analysis is yet to be done, but for the moment the consequence is Aalkohiti has dried up before the regular time. People are now forced to buy water from the tanker to serve their ends while the functioning of the recharge structures is still questionable.

No doubt, with the adaptation of Rainwater harvesting and Artificial Groundwater recharge, Aalkohiti blessed many. Setting an example, success story of Aalkohiti inspired many other communities to adapt rainwater harvesting for the conservation of the Stone spouts. But at the mean time it has again pressed all other communities to look into the system and check if their system is working properly.

But reality is Aalkohiti has not blessed now due to some shortcomings, it is vital to rectify the loopholes, correct it, if one wants to be blessed with Aalkohiti for ages.