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Rainwater Harvesting We, humans hardly think about the importance of water. Water, the most important need of all living beings on this earth is scarce today. We simply turn on the water tap and waste safe and drinkable water. As we continue to exhaust known water sources or draw more water from water reservoirs, we may soon learn the true value of water. Rainwater harvesting is a practical water conservation concept. If we can harvest rainwater for non-potable uses (washing, cleaning, etc.), then we can reduce the demand on our potable water supplier, and reduce our monthly water bill as well. The most asked question is, “how do you harvest rainwater?” To the uninitiated, rainwater harvesting seems complicated, but in reality, it is simple. By placing a drum under a rain water outlet pipe on the terrace, rainwater harvesting can begin. Rainwater harvesting reduces the need for water dependence from other external sources. This conserves water. Rainwater harvesting saves energy associated with delivering water from distant reservoirs and treating it to drinking water standards. At the same time, rainwater harvesting reduces storm water runoff, which cuts down on erosion and reduces nonpoint source pollution. It protects our creeks, rivers, and estuaries from lawn fertilizer and pesticides, car oil, trash, and other pollutants that get washed into storm drains. Last but not least, you can reduce your water bill. How much does a rain water harvesting system cost? Rain barrels can be converted from surplus, non-contaminated drums. Purchased rain barrels start at about Rs 400. Larger cisterns start at 300 gallons and, depending upon the space available and restrictive covenants in effect, can be 1,000 to 10,000 gallons or more. The least expensive barrels are made of polypropylene. Metal, wood and concrete are more expensive alternatives. Costs range from a low of about Rs per gallon for large fibreglass tanks to up to Rs per gallon for welded steel tanks. As tank sizes increase, unit costs per gallon of storage decreases. Processing rainwater for potable uses is more complicated. If potable water is available from a centralized water system, potable rainwater systems are unnecessary, expensive and redundant. A potable rainwater system would never “pay for itself” if good, high quality water is available at the tap. However, it can be a financially simple alternative to digging a well. More than 60 gallons of rainwater can be collected off the roof of a 10’x10’ garden shed in just a 1” rain. For 1,000 square feet of roof area, every inch of rainfall can produce up to 623 gallons of pure, clean rainwater. To estimate the amount of water your catchment surface can collect, multiply the impermeable collection area’s footprint (measured in square feet) by the rainfall in feet, then multiply the total by 7.5. Regional rainfall is not distributed evenly over twelve months. So during the rainy season, there may be abundant rainfall when the storage containers are already full. During the dry season, the amount of water available to you will depend as much on your storage capacity as on the amount of rain the previous season. Regardless of the complexity of the system, the domestic rainwater harvesting system comprises six basic components: Catchment surface can be any type of roof surface when water is harvested for landscape irrigation. Metal roofs are very long lasting and work better than wood or composite shingles. Asphalt shingle, wood shingle, and tar and gravel roofs are acceptable for collecting irrigation water but should not be used for potable water because of toxins that can leach into the water supply. Gutters and downspouts channel water from the roof to the tank. The most common materials for gutters and downspouts are half-round PVC, vinyl, pipe, seamless aluminium, and galvanized steel. For potable water systems, lead cannot be used as gutter solder. Leaf screens, first-flush diverters, and roof washers remove debris and dust from the captured rainwater before it goes to the tank. A site with extensive tree cover may require some sort of leaf omitting device. Some method of discarding the first flush of rain from the roof is necessary to remove debris and accumulated dust and pollutants. Storage tanks (cisterns) must be opaque to inhibit algae growth. For potable systems, storage tanks used must never have been used to store toxic materials. Tanks must be covered and vents screened to discourage mosquito breeding. Tanks used for potable systems must be accessible for cleaning. Black and green polypropylene tanks are available in most markets. Metal, wood, and concrete are more expensive alternatives when aesthetic considerations are important. Delivery system can be gravity-fed or pumped to the end use. Drip systems and soaker hoses need 15- 20 pounds per square inch (psi) of pressure to work correctly. Methods of irrigation like basin flooding or “T-Tape” (a drip system that functions on 2-10 psi) can be used for low pressure systems. Treatment/purification is required for potable systems to make the water safe to drink. Typical purification methods include charcoal filtration, UV light, ozonation, membrane filtration, and chlorination. The key issue for operation and maintenance is keeping the system clean and leak-free. Proper system design to prevent impurities from entering the system will greatly simplify upkeep. For a non-potable system used for hose irrigation, if tree overhang is present, leaf screens on gutters and a roof washer diverting 10 gallons for every 1,000 square feet of roof is sufficient. If drip irrigation is planned, sediment filtration may be necessary to prevent emitters from clogging. For potable water systems, the water should be filtered and disinfected to remove any disease-causing pathogens from stored water. System owners should regularly clean gutters and First-flush devices. In addition, owners of potable systems must adopt a regimen of changing out filters regularly, maintaining disinfection equipment, and regularly testing water quality.

Rainwater Harvesting

We, humans hardly think about the importance of water. Water, the most important need of all living beings on this earth is scarce today. We simply turn on the water tap and waste safe and drinkable water. As we continue to exhaust known water sources or draw more water from water reservoirs, we may soon learn the true value of water. Rainwater harvesting is a practical water conservation concept. If we can harvest rainwater for non-potable uses (washing, cleaning, etc.), then we can reduce the demand on our potable water supplier, and reduce our monthly water bill as well. The most asked question is, “how do you harvest rainwater?” To the uninitiated, rainwater harvesting seems complicated, but in reality, it is simple. By placing a drum under a rain water outlet pipe on the terrace, rainwater harvesting can begin.

Rainwater harvesting reduces the need for water dependence from other external sources. This conserves water.
Rainwater harvesting saves energy associated with delivering water from distant reservoirs and treating it to drinking water standards. At the same time, rainwater harvesting reduces storm water runoff, which cuts down on erosion and reduces nonpoint source pollution. It protects our creeks, rivers, and estuaries from lawn fertilizer and pesticides, car oil, trash, and other pollutants that get washed into storm drains. Last but not least, you can reduce your water bill.

How much does a rain water harvesting system cost? Rain barrels can be converted from surplus, non-contaminated drums. Purchased rain barrels start at about Rs 400. Larger cisterns start at 300 gallons and, depending upon the space available and restrictive covenants in effect, can be 1,000 to 10,000 gallons or more. The least expensive barrels are made of polypropylene. Metal, wood and concrete are more expensive alternatives. Costs range from a low of about Rs per gallon for large fibreglass tanks to up to Rs per gallon for welded steel tanks. As tank sizes increase, unit costs per gallon of storage decreases. Processing rainwater for potable uses is more complicated. If potable water is available from a centralized water system, potable rainwater systems are unnecessary, expensive and redundant. A potable rainwater system would never “pay for itself” if good, high quality water is available at the tap. However, it can be a financially simple alternative to digging a well.
More than 60 gallons of rainwater can be collected off the roof of a 10’x10’ garden shed in just a 1” rain. For 1,000 square feet of roof area, every inch of rainfall can produce up to 623 gallons of pure, clean rainwater.

To estimate the amount of water your catchment surface can collect, multiply the impermeable collection area’s footprint (measured in square feet) by the rainfall in feet, then multiply the total by 7.5. Regional rainfall is not distributed evenly over twelve months. So during the rainy season, there may be abundant rainfall when the storage containers are already full. During the dry season, the amount of water available to you will depend as much on your storage capacity as on the amount of rain the previous season.

Regardless of the complexity of the system, the domestic rainwater harvesting system comprises six basic components:
Catchment surface can be any type of roof surface when water is harvested for landscape irrigation. Metal roofs are very long lasting and work better than wood or composite shingles. Asphalt shingle, wood shingle, and tar and gravel roofs are acceptable for collecting irrigation water but should not be used for potable water because of toxins that can leach into the water supply.

Gutters and downspouts channel water from the roof to the tank. The most common materials for gutters and downspouts are half-round PVC, vinyl, pipe, seamless aluminium, and galvanized steel. For potable water systems, lead cannot be used as gutter solder.
Leaf screens, first-flush diverters, and roof washers remove debris and dust from the captured rainwater before it goes to the tank. A site with extensive tree cover may require some sort of leaf omitting device. Some method of discarding the first flush of rain from the roof is necessary to remove debris and accumulated dust and pollutants.

Storage tanks (cisterns) must be opaque to inhibit algae growth. For potable systems, storage tanks used must never have been used to store toxic materials. Tanks must be covered and vents screened to discourage mosquito breeding. Tanks used for potable systems must be accessible for cleaning. Black and green polypropylene tanks
are available in most markets. Metal, wood, and concrete are more expensive alternatives when aesthetic considerations are important.

Delivery system can be gravity-fed or pumped to the end use. Drip systems and soaker hoses need 15- 20 pounds per square inch (psi) of pressure to work correctly. Methods of irrigation like basin flooding or “T-Tape” (a drip system that functions on 2-10 psi) can be used for low pressure systems.

Treatment/purification is required for potable systems to make the water safe to drink. Typical purification methods include charcoal filtration, UV light, ozonation, membrane filtration, and chlorination.
The key issue for operation and maintenance is keeping the system clean and leak-free. Proper system design to prevent impurities from entering the system will greatly simplify upkeep. For a non-potable system used for hose irrigation, if tree overhang is present, leaf screens on gutters and a roof washer diverting 10 gallons for every 1,000 square feet of roof is sufficient. If drip irrigation is planned, sediment filtration may be necessary to prevent emitters from clogging. For potable water systems, the water should be filtered and disinfected to remove any disease-causing pathogens from stored water. System owners should regularly clean gutters and
First-flush devices. In addition, owners of potable systems must adopt a regimen of changing out filters regularly, maintaining disinfection equipment, and regularly testing water quality.