Rooftop rainwater harvesting system

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A water harvesting system in which rain falling on a roof is led through connecting pipes into a ferro-cement water collecting jar Many households in Nepal’s midhills suffer from water shortages during the pronounced dry season. The technology described here – harvesting roofwater during times of heavy rainfall for later use – is a promising way of improving people’s access to water for household use, especially for households with no or only limited access to spring or stream water. The technology has yet to be extensively adopted Nepal’s midhills.

The technology was introduced in the Jhikhu Khola watershed to demonstrate an
alternative source of water for domestic use (mainly drinking water). This technology is appropriate for scattered rural households in mountainous areas. The harvesting system consists of a catchment roof, conveyance pipes, and a storage jar. The pipes include a gutter system made from longitudinally split polythene pipe which has a flushing system that allows the system to be periodically flushed clean.

The collected water enters a 500 or 2000 litre capacity ferro-cement jar made using a mould (see photo). A preconstructed mould made from iron rods and polythene pipes is installed on a concrete base plate. Metal wires are extended from the base plate over the main mould to the top. Chicken mesh is then wrapped over the mould and tied securely with thin wire. A cement coating is applied over the metal structure. The jar is finished with three coatings of cement and the opening is covered with a fine nylon mesh to filter out undesired coarse matter. A tin lid is placed over the top.

A tap is fixed about 20 cm above the ground. This height allows for water to be
collected in the typical 15 litre local water vessels (gagri) and avoids collection of
too much water in bigger vessels as well as minimising the dead storage of water
(Nakarmi et al. 2003). Trained masons can easily install the entire system. Provided all the materials and the mould are available, the entire system can be put together in about a week.

The main maintenance task is to keep the roof clean, especially after long dry
periods. This is done using the gutter pipe flushing system in which the fi rst dirty
water from the roof is diverted away from the jar.

Achievement

Harvested rainwater has saved almost one workday per day per family due to reduced water fetching time in this case referring to the rainy season,however water will generally be used during the dry season

Publicise the economic benefits of the technology through experience sharing programmes
Women are responsible for fetching water and so the technology reduces their workloads

Implement a larger scale programme to promote the technology The jars are more durable than plastic tanks

Carry out regular maintenance to keep systems in good working order
The stored water can be kept for use in emergencies such as to prepare food for guests during busy times like rice planting and harvesting, and during
festivals

Share experiences to extend adoption of the technology

  • Strengthened community institution: together with adopters, other potential local adopters have started discussing options to overcome the scarcity of water and are searching for funds to

  • install roofwater harvesting systems

  • Improved knowledge of soil and water conservation and erosion through training, demonstration, and knowledge sharing Increased water availability in dry season

  • Better sanitation from more water available for washing leading to improved health
    Water is available near the house

  • Greatly reduced time needed to fetch water, reducing women’s workloads

  • Reduced risk of injury from carrying water along slippery and steep tracks

  • Less chance of disputes over turns to fetch water
    Increased availability of water for neighbours during scarce periods

  • Reduced downstream flooding
    Reduced downstream siltation

Implementers

Saraswoti Bhetwal - Lamidihi, Panchkhal VDC, Ward No.4
Harimaya Panday - Dhotra, Panchkhal, VDC, Ward No. 9
Nara Bahadur Panday - Dhotra, Panchkhal, VDC, Ward No. 9
Ramesh Bika - Dhotra, Panchkhal, VDC, Ward No. 9
Pitambar Danuwar - Dhotra, Panchkhal, VDC, Ward No. 8
Rama Danuwar - Dhotra, Panchkhal, VDC, Ward No. 8
Januka Dhungel - Ekanta Basti, Dhotra, Panchkhal, VDC
Nirmala Shrestha - Bakhreldihi, Panchkhal, VDC, Ward No. 7
Krishna Bahadur Baniya - Bakhreldihi, Panchkhal, VDC, Ward No. 7
Basanta Lal Shrestha - Kharelthok VDC, Ward No. 1
Buddha Laxmi Shrestha - Kharelthok VDC, Ward No. 1
Ramesh Kharel - Kharelthok VDC, Ward No. 5
Mahalaxmi Kharel - Kharelthok VDC, Ward No. 4

Duartion

January - December

Geographical Coverage


For further information contact:

Madhav Dhakal/Vijay Danuwar

Comments

Pasang wrote on 2016-05-27 10:26

do you have any construction method for these type of System ?