Rooftop rainwater harvesting system [Nepal]
- Creation:
- Update:
- Compiler: Madhav Dhakal
- Editor: –
- Reviewers: David Streiff, Deborah Niggli, Alexandra Gavilano
Akase paani sankalan pranali - Nepali
technologies_1497 - Nepal
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Expand all Collapse all1. General information
1.2 Contact details of resource persons and institutions involved in the assessment and documentation of the Technology
SLM specialist:
SLM specialist:
Name of project which facilitated the documentation/ evaluation of the Technology (if relevant)
Book project: Water Harvesting – Guidelines to Good Practice (Water Harvesting)Name of the institution(s) which facilitated the documentation/ evaluation of the Technology (if relevant)
ICIMOD International Centre for Integrated Mountain Development (ICIMOD) - Nepal1.3 Conditions regarding the use of data documented through WOCAT
The compiler and key resource person(s) accept the conditions regarding the use of data documented through WOCAT:
Yes
2. Description of the SLM Technology
2.1 Short description of the Technology
Definition of the Technology:
A water harvesting system in which rain falling on a roof is led through connecting pipes into a ferro-cement water collecting jar.
2.2 Detailed description of the Technology
Description:
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 in Nepal’s midhills.
Purpose of the Technology: 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 mountaineous 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.
Establishment / maintenance activities and inputs: 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 first dirty water from the roof is diverted away from the jar.
2.3 Photos of the Technology
2.5 Country/ region/ locations where the Technology has been applied and which are covered by this assessment
Country:
Nepal
Region/ State/ Province:
Kharelthok, Sathighar, Panchkhal, Hokse and Patalekhet VDCs of the Jhikhu Khola watershed
Further specification of location:
Kavrepalanchowk district
Specify the spread of the Technology:
- applied at specific points/ concentrated on a small area
Comments:
Roof rainwater harvesting jars were demonstrated mostly in the villages located at the watershed divides, hilltops, and elevated terraces where communities face chronic water shortage particularly during the dry period.
Map
×2.6 Date of implementation
If precise year is not known, indicate approximate date:
- less than 10 years ago (recently)
2.7 Introduction of the Technology
Specify how the Technology was introduced:
- through projects/ external interventions
Comments (type of project, etc.):
Water harvesting is an ancient practice, the system used in the Jhikhu Khola watershed came from Thailand, so the technology is often called 'Thai jar". In Nepal, the Rural Water Supply and Sanitation Support Programme (RWSSSP), which is jointly funded by the Government of Finland and His Majesties Government of Nepal, introduced it in the water deficit districts of western Nepal (Arghakhanchi, Gulmi, Kapilvastu, Nawalparasi, Palpa, Parbat, and Rupandehi).
3. Classification of the SLM Technology
3.1 Main purpose(s) of the Technology
- Access to water
3.2 Current land use type(s) where the Technology is applied
Settlements, infrastructure
- Settlements, buildings
Remarks:
courtyard
Comments:
Major land use problems (compiler’s opinion): Inadequate water supply during the late winter and pre-monsoon months and sediment contamination during the wet season. The discharge from traditional water sources like dug-out ponds, springs, seepage ‘holes’, shallow wells and streamlets becomes limited soon after the end of the monsoon.
Major land use problems (land users’ perception): Many settlements are located on ridge tops and most water sources are located below making it difficult to provide water to households through networks of pipes. Women and girls often face hardship in carrying the water uphill, especially during the monsoon when trails are slippery.
Constraints of settlement / urban
Number of growing seasons per year: 3
Longest growing period in days: 150; Longest growing period from month to month: Jun - Oct; Second longest growing period in days: 120; Second longest growing period from month to month: Nov - Feb
3.5 SLM group to which the Technology belongs
- water harvesting
3.6 SLM measures comprising the Technology
structural measures
- S5: Dams, pans, ponds
3.7 Main types of land degradation addressed by the Technology
physical soil deterioration
- Pw: waterlogging
Comments:
Main causes of degradation: change of seasonal rainfall
3.8 Prevention, reduction, or restoration of land degradation
Specify the goal of the Technology with regard to land degradation:
- reduce land degradation
4. Technical specifications, implementation activities, inputs, and costs
4.1 Technical drawing of the Technology
Technical specifications (related to technical drawing):
A water harvesting system with roof catchment, connecting pipes and storage tank.
Technical knowledge required for field staff / advisors: high
Technical knowledge required for land users: high
Main technical functions: water harvesting / increase water supply
Structural measure: Dam/ pan/ pond
Material: Concrete
Structural measure: Jar
Structural measure: Gutter
Structural measure: pipes
Construction material (other): Cement
Author:
A.K. Thaku
4.2 General information regarding the calculation of inputs and costs
Specify how costs and inputs were calculated:
- per Technology unit
Specify unit:
Rooftop rainwater harvesting system
Specify currency used for cost calculations:
- USD
Indicate average wage cost of hired labour per day:
2.10
4.3 Establishment activities
Activity | Timing (season) | |
---|---|---|
1. | Construct the concrete base plate with the help of base moluld | 1st day of a week |
2. | Curing work | 2nd to 7th days of a week |
3. | Final checking and metal cap putting over the top of the jar | 7th day of a week |
4. | First coat of cement | 2nd day of a week |
5. | Gutter and pipe fitting; including flush pipe | 4th day of a week |
6. | Inner coat of cement | 6th day of a week |
7. | Main mould installation with the help of metal wires, wrapping of chicken mesh | 2nd day of a week |
8. | Removal of mould | 6th day of a week |
9. | Second coat of cement | 3rd day of a week |
4.4 Costs and inputs needed for establishment
Specify input | Unit | Quantity | Costs per Unit | Total costs per input | % of costs borne by land users | |
---|---|---|---|---|---|---|
Labour | Construction of rooftop rainwater harvesting system | Persons/unit | 19.5 | 2.1 | 40.95 | 25.0 |
Construction material | Cement | unit | 1.0 | 23.6 | 23.6 | |
Construction material | Sand and aggregate | unit | 1.0 | 1.4 | 1.4 | 100.0 |
Construction material | Chicken wire mesh | unit | 1.0 | 20.9 | 20.9 | |
Construction material | Metal jar cover | unit | 1.0 | 5.5 | 5.5 | |
Construction material | Plastic sheet/mosquito screen | unit | 1.0 | 1.5 | 1.5 | |
Construction material | Polyethylene, pipes, reducer | unit | 1.0 | 23.7 | 23.7 | |
Construction material | Nail, clamps, pipe elbow etc. | unit | 1.0 | 3.6 | 3.6 | |
Construction material | Brass tap. socket, seal tap | unit | 1.0 | 3.5 | 3.5 | |
Other | Paint | unit | 1.0 | 2.1 | 2.1 | |
Total costs for establishment of the Technology | 126.75 | |||||
Total costs for establishment of the Technology in USD | 126.75 |
Comments:
Duration of establishment phase: 0.25 month(s)
Materials: cement (kg) 23.6 materials sand,aggregate (m3) 1.4 100 materials chicken wire mesh (m) 17.5 materials Iron wire (kg) 3.3 materials metal jar cover (no) 5.5 materials mosquito screen (m) 0.5 materials plastic sheet (m) 1 materials binding wire (kg) 0.1 materials snowcem paint (kg) 1.4 materials enamail paint (litre) 0.7 materials 90 mm HDP pipe (m) 10.3 materials 63 mm HDP pipe (m) 6.2 materials 40 mm HDP pipe (m) 6.8 materials reducer (no) 0.4 materials plain and roofing nails (kg) 0.2 materials metal clamp (no) 1.4 materials elbow, tee,end cap (no) 2.1 materials brass tap with latches (no) 2.1 materials 0 .5*10 inch GI nipple(no) 0.2 materials 1*10 inch GI nipple(no) 0.2 materials 1inch end cap (no) 0.7 materials GI socket (no) 0.2 materials thread seal tap (no) 0.1 Additional info Q 3.1.1.4: - less chance of disputes over turns to fetch water - medium General comments: Water harvesting is an ancient practice. The system used in the Jhikhu Khola watershed comes from Thailand, so the technology is often called ‘Thai jar’. In Nepal, the Rural Water Supply and Sanitation Support Programme (RWSSSP) introduced it in the water deficit districts of western Nepal.
4.5 Maintenance/ recurrent activities
Activity | Timing/ frequency | |
---|---|---|
1. | Cleaning the jar | dry months/one or twice in a year |
2. | Flushing contaminated water | After a long dry spell/whenever required |
4.6 Costs and inputs needed for maintenance/ recurrent activities (per year)
Specify input | Unit | Quantity | Costs per Unit | Total costs per input | % of costs borne by land users | |
---|---|---|---|---|---|---|
Labour | Cleaning the system | Persons/unit | 7.0 | 2.1 | 14.7 | 100.0 |
Total costs for maintenance of the Technology | 14.7 | |||||
Total costs for maintenance of the Technology in USD | 14.7 |
Comments:
Machinery/ tools: hacksaw, steel scissors, hammer, pliers, wrench, trowel, steel pan bucket, and jug
Per unit cost of structure. The above mentioned cost is for unit water harvesting system. It can not be converted into hectare basis. It was estimated in 2006.
4.7 Most important factors affecting the costs
Describe the most determinate factors affecting the costs:
The mould and tools were provided by the project and can be used to install many water harvesting systems. Therefore, the cost of tools are not included here. Material costs fluctuate from time to time. The transport costs will vary according to the remoteness of the site. During 1999/2000, the cost of a system varied from US$80 to US$120, of which land users contributed about US$40 by providing the unskilled labour and locally available materials like sand and fine aggregates (calculated at an exchange rate of US$1 = NRs 73).
5. Natural and human environment
5.1 Climate
Annual rainfall
- < 250 mm
- 251-500 mm
- 501-750 mm
- 751-1,000 mm
- 1,001-1,500 mm
- 1,501-2,000 mm
- 2,001-3,000 mm
- 3,001-4,000 mm
- > 4,000 mm
Agro-climatic zone
- humid
Thermal climate class: subtropics
5.2 Topography
Slopes on average:
- flat (0-2%)
- gentle (3-5%)
- moderate (6-10%)
- rolling (11-15%)
- hilly (16-30%)
- steep (31-60%)
- very steep (>60%)
Landforms:
- plateau/plains
- ridges
- mountain slopes
- hill slopes
- footslopes
- valley floors
Altitudinal zone:
- 0-100 m a.s.l.
- 101-500 m a.s.l.
- 501-1,000 m a.s.l.
- 1,001-1,500 m a.s.l.
- 1,501-2,000 m a.s.l.
- 2,001-2,500 m a.s.l.
- 2,501-3,000 m a.s.l.
- 3,001-4,000 m a.s.l.
- > 4,000 m a.s.l.
Comments and further specifications on topography:
Landforms: Also valley floors
5.4 Water availability and quality
Water quality (untreated):
poor drinking water (treatment required)
Comments and further specifications on water quality and quantity:
Water quality (untreated): More in rainy season (June- September), less in April/May
5.6 Characteristics of land users applying the Technology
Off-farm income:
- 10-50% of all income
Relative level of wealth:
- poor
Individuals or groups:
- individual/ household
Gender:
- women
- men
Indicate other relevant characteristics of the land users:
Land users applying the Technology are mainly common / average land users
Population density: 200-500 persons/km2
Annual population growth: 2% - 3%
15% of the land users are rich and own 35% of the land.
35% of the land users are average wealthy and own 40% of the land.
50% of the land users are poor and own 25% of the land (as ranked by the land users).
Off-farm income specification: In most farm households off-farm income plays at least a minor and increasingly a major role. Occasional opportunities for off-farm income present themselves in the form of daily
5.7 Average area of land used by land users applying the Technology
- < 0.5 ha
- 0.5-1 ha
- 1-2 ha
- 2-5 ha
- 5-15 ha
- 15-50 ha
- 50-100 ha
- 100-500 ha
- 500-1,000 ha
- 1,000-10,000 ha
- > 10,000 ha
Is this considered small-, medium- or large-scale (referring to local context)?
- medium-scale
5.8 Land ownership, land use rights, and water use rights
Land ownership:
- individual, titled
Land use rights:
- individual
Water use rights:
- communal (organized)
6. Impacts and concluding statements
6.1 On-site impacts the Technology has shown
Socio-economic impacts
Production
production area
Comments/ specify:
by the house to accommodate the water jar
Water availability and quality
drinking water availability
Comments/ specify:
in dry seasons
harvested water can be used during busy periods ( field preparation, vegetable planting, rice harvesting, and festivals).
Income and costs
workload
Quantity before SLM:
1 hour
Quantity after SLM:
5 minutes
Comments/ specify:
greatly reduced time needed to fetch water
reduced women's workload i.e. per day water fetching time reduced from about 12 hours to about 1 hour ( for the households having ~10 family members).
Other socio-economic impacts
Water is available near the house
Comments/ specify:
A house hold having 10 family member require about 12 gagree ( 1 gagree is equivalent to15 litre)
Socio-cultural impacts
community institutions
Comments/ specify:
together with adopters, other potential local adopters have started discussing options
SLM/ land degradation knowledge
Comments/ specify:
through training, demonstration, and knowledge sharing
livelihood and human well-being
Comments/ specify:
Improved heath condition due to clean water availability
Sanitation
Comments/ specify:
more water avilable forwashing leading to improved health
Risk of injury from carrying water along slippery and steep tracks
6.2 Off-site impacts the Technology has shown
downstream flooding
Comments/ specify:
a little portion of rainfall traped directly from the roof and collected at the courtyard
downstream siltation
Comments/ specify:
reduced eroded materials from the courtyard.
availability of water for neighbours during scarce period
6.3 Exposure and sensitivity of the Technology to gradual climate change and climate-related extremes/ disasters (as perceived by land users)
Gradual climate change
Gradual climate change
Season | increase or decrease | How does the Technology cope with it? | |
---|---|---|---|
annual temperature | increase | well |
Climate-related extremes (disasters)
Meteorological disasters
How does the Technology cope with it? | |
---|---|
local rainstorm | well |
local windstorm | well |
Climatological disasters
How does the Technology cope with it? | |
---|---|
drought | not well |
Hydrological disasters
How does the Technology cope with it? | |
---|---|
general (river) flood | well |
Other climate-related consequences
Other climate-related consequences
How does the Technology cope with it? | |
---|---|
reduced growing period | well |
6.4 Cost-benefit analysis
How do the benefits compare with the establishment costs (from land users’ perspective)?
Short-term returns:
slightly negative
Long-term returns:
very positive
How do the benefits compare with the maintenance/ recurrent costs (from land users' perspective)?
Short-term returns:
very positive
Long-term returns:
very positive
Comments:
Although the initial investment is high, the users immediately get more water. The high cost of installing the system means that the short term benefits are slightly negative.
6.5 Adoption of the Technology
- single cases/ experimental
If available, quantify (no. of households and/ or area covered):
46 households in an area of 1 - 10 sq km (200 - 500 persons/sq km)
Of all those who have adopted the Technology, how many did so spontaneously, i.e. without receiving any material incentives/ payments?
- 11-50%
Comments:
74% of land user families have adopted the Technology with external material support
34 land user families have adopted the Technology with external material support
Comments on acceptance with external material support: survey results
26% of land user families have adopted the Technology without any external material support
12 land user families have adopted the Technology without any external material support
Comments on spontaneous adoption: survey results
There is a little trend towards spontaneous adoption of the Technology
Comments on adoption trend: The number of households applying the technology is increasing without further incentives being provided.
6.7 Strengths/ advantages/ opportunities of the Technology
Strengths/ advantages/ opportunities in the land user’s view |
---|
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. How can they be sustained / enhanced? Share experiences to extend adoption of the technology |
Harvested water is tastier due to being cooler compared to the water collected in the polythene tank. How can they be sustained / enhanced? Laboratory analysis of the harvested rainwater in different time period, i.e. from 1st month of harvest to 12th month could help to know the quality status. |
Strengths/ advantages/ opportunities in the compiler’s or other key resource person’s view |
---|
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. How can they be sustained / enhanced? Publicise the economic benefits of the technology through experience sharing programmes. |
Women are responsible for fetching water and so the technology reduces their workloads. How can they be sustained / enhanced? Implement a larger scale programme to promote the technology. |
The jars are more durable than plastic tanks. How can they be sustained / enhanced? Carry out regular maintenance to keep systems in good working order. |
6.8 Weaknesses/ disadvantages/ risks of the Technology and ways of overcoming them
Weaknesses/ disadvantages/ risks in the land user’s view | How can they be overcome? |
---|---|
The technology is expensive for poor households. | External support is needed for poor households to afford this system. |
The height of the tap is very low which makes it inconvenient to collect water in the gagree. | It was designed to use collected water efficiently, the tap height can be raised, which means that the dead storage is increased, i.e. more water is unavailable for use. |
There are chances of the jar’s base plate subsiding due to lack of compactness of foundation. | The area of base plate should be made more compact. |
Weaknesses/ disadvantages/ risks in the compiler’s or other key resource person’s view | How can they be overcome? |
---|---|
2,000 litre capacity jars barely meet the dry season needs of a household. | Larger sized jars or more than one jar need to be built to meet most household’s requirements. |
Microbiological contamination (total and faecal coliform bacteria) and levels of phosphate above the EC maximum were found in a number of the jars caused by bird droppings and dust particles from the roof. | Regularly clean catchment roofs and treat water before drinking by boiling or chlorinating. Rainwater has a low mineral content which can be harmful for the human body, if taken in large quantities (due to reverse osmosis process). |
This technology is not suitable for temple roofs because such roofs are usually home to large numbers of pigeons, and their excreta will contaminate rainwater that falls there. | Avoid badly contaminated catchments. |
7. References and links
7.1 Methods/ sources of information
7.2 References to available publications
Title, author, year, ISBN:
Sharma, C. (2001) Socioeconomic IndicativeImpact Assessment and Benchmark Study on Rooftop Rainwater Harvesting, Kabhrepalanchok District, Nepal, a report submitted to ICIMOD, Kathmandu, Nepal
Available from where? Costs?
ICIMOD
Title, author, year, ISBN:
ICIMOD (2000) Water Harvesting Manual, unpublished manual prepared for PARDYP Project, ICIMOD
Available from where? Costs?
ICIMOD
Title, author, year, ISBN:
ICIMOD (2007) Good Practices in Watershed Management, Lessons Learned in the Mid Hills of Nepal. Kathmandu: ICIMOD
Available from where? Costs?
ICIMOD
Title, author, year, ISBN:
Lessons Learned from the People and Resource Dynamics Project , PARDYP/ICIMOD. 2006.
Available from where? Costs?
ICIMOD
Title, author, year, ISBN:
Nakarmi, G.; Merz, J.; Dhakal, M. (2003) ‘Harvesting Roof Water for Livelihood Improvement: A Case Studyof the Yarsha Khola Watershed, Eastern Nepal’. In News Bulletin of Nepal Geological Society, 20: 83-87
Title, author, year, ISBN:
Nakarmi, G.; Merz, J. (2001) Harvesting Rain Water for Sustainable Water Supplies to Rural Households in the Yarsha Khola Watershed, a report submitted to Kirchgemeinde Zuoz, Switzerland and ICIMOD, Kathmandu, Nepal
Available from where? Costs?
ICIMOD
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