Rainwater Harvesting System
Process of Jalharvest System
Saturday, March 17, 2012
Friday, March 16, 2012
Benefits of Rainwater Harvesting System
Source:
Earth, Water, Fire, Air and Sky are the five basic elements of life. Water is the most important elements and no human being can survive without it. People are always complaining about Shortage of water in summer. In monsoon the flood caused on the roads and overflowing drains that has them cribbing. All that overload water goes waste. System of collection rainwater and conserving for future needs has traditionally been practiced in India. In this article there are benefits of rain water harvesting.
Rainwater harvesting is the compilation and storage of rain water that falls upon the roof and using it as a free resource. It can be used in residential, commercial and industrial projects where pure water is desired. Nowadays shortage of good quality water has become a major problem. Rain water harvesting is necessary because surface water is insufficient and we have to depend on ground water, to preserve surface water runoff during monsoon, ground water recharging of has diminished due to rapid urbanization and to reduce soil erosion. There are two types of harvesting Systems which collect roof runoff for household use and Systems which use in field or adjoining catchment to provide supplemental irrigation for agriculture.
The traditional techniques to store rain water are underground tanks, ponds, check dams, weirs etc. Recharge to ground water is a new concept of rain water harvesting and the structures generally used are Pits, Trenches, Dug wells, Hand pumps, Recharge wells, Recharge Shafts, Lateral shafts with bore wells and Spreading techniques.
Benefits of rain water harvesting system:
- Rainwater is a comparatively clean and totally free source of water.
- Rainwater is improved for scenery plants and gardens because it is not chlorinated.
- It can supplement other sources of water supply such as groundwater or municipal water connections.
- It lower the water supply cost.
- It can provide an excellent back-up source of water for emergencies.
- It is socially acceptable and environmentally responsible.
- It uses simple technologies that are inexpensive and easy to maintain.
- Reduced flood flows and topsoil loss.
- It is free; the only cost is for collection and use.
- It reduces the contamination of surface water with sediments, fertilizers and pesticides from rainwater run-off resulting in cleaner lakes, rivers, oceans and other receivers of storm water.
- It is used in those areas which face insufficient water resources.
- It is good for laundry use as rainwater is soft and lowers the need for detergents.
- It can be used to recharge groundwater.
- It minimizes the runoff which blocks the storm water drains.
Rainwater harvesting is suitable for places where:
- Water is too hard or rich in minerals.
- Ground water is insufficient.
- Ground water is impure.
- Population density is low.
- Terrain is rugged or mountainous.
- Electricity & water prices are rising.
- Seismic & flooding events are common.
- Conservation is an objective.
- The aquifer is at risk of saltwater intrusion.
Uses of collected rain water:
- Hand water the lawn and garden.
- Toilet flush.
- Washing clothes, vehicles and pets.
- Refill swimming pool.
- Replace the use of tap water with rainwater to wash your driveways and sidewalks.
- Use it for all potable needs when properly filtered and disinfected.
- Use it for industrial processes instead of municipally treated water.
- Connect rainwater collection system to irrigation system.
Video of Rainwater Harvesting from YouTube.
Fundamentals of Rainwater Harvesting
Source: aguasolutions.com
“Only about 70 % of the population receive water of potable quality”. (As estimated by AyA’s National Water Laboratory).
“In most of the regions of the country water production capacity is very close to current demand, so the risk of facing water deficits in the near future is high and in fact, various cities already suffer water shortage and rationing”.
“Most water systems are operating with very high water losses, usually over 50%, a value which reflects a high level of inefficiency and compromises continuity of service”
“96% of all urban wastewater collected is discharged into rivers and receiving bodies without any treatment”
“Revenues do not permit adequate management of the infrastructure and the financial
situation of the sector is precarious”.
- Background Water Facts:
RWH Examples ... from around the World
1) What is Rain Water Harvesting?
RWH is simply collecting, storing and purifying the naturally soft and pure rainfall that falls upon your roof. Rainwater may be utilized for both potable and non-potable requirements such as ... - drinking, cooking, bathing (potable quality)
- swimming pool replenishment
- toilet flushing
- laundry (reduces detergent & bleach)
- landscape irrigation
- livestock & animals
- AyA
- Municipal service
- Groundwater well
- Rain water harvesting
 |
| Example: RWH with concrete tank |
 |
| Example: RWH with twin concrete below grade |
2) Why Harvest the Rain?
RWH is most suitable where ...- groundwater is scarce
- groundwater is contaminated
- terrain is rugged or mountainous
- seismic & flooding events are common
- the aquifer is at risk of saltwater intrusion
- population density is low
- electricity & water prices are rising
- water is too hard or mineral laden
- consumers must restrict salt/chlorine intake
- where utility service is unreliable
... and where ... - conservation is an objective
- Availability not subject to outside utility control
- Not subject to pipelines interruption (seismic)
- Quality is controlled by the consumer
- Available even when power is interrupted
- Reduces run-off and erosion
- Available even when storms & disaster strike
- Available immediately for fire suppression
- Reduces mosquito breeding grounds (Dengue Fever)
- Thermal mass can naturally cool buildings
- Ideal for people on low sodium diets or with health concerns (weakened immunity systems)
- naturally pure
- naturally soft (no dissolved minerals)
- free for those who collect it
- sustainable
- free of chlorine and its byproducts
- free of pesticides and other man-made contaminants
- abundantly available in Costa Rica
3) How to Harvest the Rain ...
The six basic components of a Rain Water Harvesting system include:- Catchment: roof surface to collect the rain
- Conveyance: channels or pipes from roof or catchment area to storage
- Roof washing: ‘first flush’ diverter system to filter and remove contaminants
- Storage: cisterns or tanks where collected rainwater is securely stored – i.e. insect proof
- Purification: includes filtration, ozone or UV light to purify the collected rainwater for potable use
- Distribution: system that delivers the rainwater, usually including a small pump and pressure tank
4) Background information ...
 |
| Rainfall Map - Ministerio de Agricultura y Ganaderia |
- AyA & Ministerio de Salud both recognize RWH as an approved supply source of potable water
- Guanacaste Rainfall:
- Liberia area: (32 years of data)
- Annual average = 63.5 inches
- Annual average = 1,614 mm
- 2005 total = 110 inches
- Bagaces area: (28 years of data)
- Annual average = 65.7 inches
- Annual average = 1,670 mm
- 2005 total = 89.6 inches
- Coastal area:
- Annual average = 60 inches
- Annual average = 1,524 mm
- 2005 total = 98.4 inches Rainfall Map - Ministerio de Agricultura y Ganadería
“Only about 70 % of the population receive water of potable quality”. (As estimated by AyA’s National Water Laboratory).
“In most of the regions of the country water production capacity is very close to current demand, so the risk of facing water deficits in the near future is high and in fact, various cities already suffer water shortage and rationing”.
“Most water systems are operating with very high water losses, usually over 50%, a value which reflects a high level of inefficiency and compromises continuity of service”
“96% of all urban wastewater collected is discharged into rivers and receiving bodies without any treatment”
“Revenues do not permit adequate management of the infrastructure and the financial
situation of the sector is precarious”.
- Background Water Facts:During the past century, the world population has tripled, but water use has increased six-fold. The UN’s Population Division projects that we are adding 240,000 people each day, heading toward a global population of 8.04 billion by the year 2025…. 50% will live in ‘water stressed’ areas.- Background Water Facts:
Population growth in the Central American region is the second fastest in the world after Asia, and 59 million people are expected to live in the region by 2025. (Source: United Nations)
Agriculture consumes over 70% of Costa Rica’s water resources. As population increases, agriculture (food production) will increasingly compete with industrial and urban water consumers.
Only 2.5% of the world’s water is fresh, while 97.5% is ocean. And of that freshwater, only 0.3% is available from rivers, lakes and reservoirs. Most freshwater is locked up in polar ice, glaciers or soil moisture. Unfortunately, more and more of that precious freshwater is contaminated each year.
RWH Examples ... from around the World
- Australia* & New Zealand
- Bermuda*
- U.S. Virgin Islands*
- Singapore*
- Turks & Caicos Islands*
- India
- Barbados
- Bahamas
- Germany (500,000 systems in operation)
- Texas
- Hawaii (60,000 people depend upon RWH)
- China (21 million people depend upon RWH)
* Countries where RWH systems are required by law.
Rain Water Harvesting
Rainwater harvesting is the accumulating and storing of rainwater for reuse before it reaches the aquifer. It has been used to provide drinking water, water for livestock, water for irrigation, as well as other typical uses. Rainwater collected from the roofs of houses and local institutions can make an important contribution to the availability of drinking water. It can supplement the subsoil water level and increase urban greenery. Water collected from the ground, sometimes from areas that are especially prepared for this purpose, is called Stormwater harvesting. In some cases, rainwater may be the only available, or economical, water source. Rainwater harvesting systems can be simple to construct from inexpensive local materials, and are potentially successful in most habitable locations. Roof rainwater may not be potable and may require treatment before consumption. As rainwater rushes from your roof it may carry pollutants, such as mercury from coal burning buildings, or bird faeces. Although some rooftop materials may produce rainwater that would be harmful to human health as drinking water, it can be useful in flushing toilets, washing clothes, watering the garden, and washing cars; these uses alone halve the amount of water used by a typical home. Household rainfall catchment systems are appropriate in areas with an average rainfall greater than 200 mm (7.9 in) per year, and no other accessible water sources (Skinner and Cotton, 1992). Overflow from rainwater harvesting tank systems can be used to refill aquifers in a process called groundwater recharge; though this is a related process, it must not be confused with rainwater harvesting.
There are several types of systems to harvest rainwater, ranging from very simple home systems to complex industrial systems. The rate at which water can be collected from either system is dependent on the plan area of the system, its efficiency, and the intensity of rainfall (i.e., annual precipitation (mm per annum) x square meter of catchment area = litres per annum yield) ... a 200 square meter roof catchment catching 1,000mm PA yields 200 kLPA.
ld be large enough to carry peak flows. Storage tanks should be covered to prevent mosquito breeding and to reduce evaporation losses, contamination and algal growth.
A subsurface dike is built in an aquifer to obstruct the natural flow of groundwater, thereby raising the groundwater level and increasing the amount of water stored in the aquifer. The subsurface dike at Krishi Vigyan Kendra Kannur under Kerala Agricultural University with the support of ICAR, has become an effective method for ground water conservation by means of rain water harvesting technologies. The subsurface dike has been demonstrated to be a feasible method for conserving and exploiting the groundwater resources of the Kerala state of India. The dike is now the largest rainwater harvesting system in that region.
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