Briefing of Rainwater tank

Rainwater tanks (sometimes called rain barrels in North America, referring to smaller tanks, or buckets in the UK) are tanks used to collect and store rainwater runoff,usually through pipes,off the roof.A rainwater tank is a device that collects and holds rainwater.A rainwater catchment or collection (also known as "rainwater harvesting") system can produce 2,358 liters (623 US gal) of water from 2.54 cm (1.00 in) of rainwater on a 92.9 m² (1,000 sq ft) roof.Install rainwater tanks to utilize rainwater for later use, reduce the use of mains water for economic or environmental reasons, and help achieve self-sufficiency.Stored water can be used for watering gardens, farming, flushing toilets, washing machines, washing cars, and also for drinking, especially when other water supplies are unavailable, expensive, or of poor quality, and when due care is taken that the water source is not polluted and adequately filtered .Underground rainwater tanks can also be used to retain rainwater for later release and offer several benefits.In arid climates, rain barrels are often used to store water during the rainy season for use in the dry season.

The initial cost of rainwater tanks can be high (as people think). However, many homes use small rain barrels to collect trace amounts of water for landscaping/gardening applications, not as a drinking water substitute.These small rain barrels are usually salvaged from food storage and shipping barrels,or in some cases whiskey and wine aging barrels, and are usually quite cheap.There are also many low-cost designs using locally available materials and village-level technology,suitable for developing countries where drinking water alternatives are limited.While most are properly designed to repel mosquitoes, the lack of proper filtration or closed loop systems can create breeding grounds for larvae.For tanks used for drinking water, users will be exposed to health risks if not maintained.

Tanks

Rainwater tanks can be made from plastic (polyethylene), concrete, galvanized steel as well as rust and chemical resistant materials such as fiberglass and stainless steel.Full tanks are usually installed above ground and are usually opaque to prevent the stored water from being exposed to sunlight to reduce algal blooms.Tanks may be covered and have screened inlets to exclude insects, debris, animals and bird droppings.Almost all steel tanks currently produced for household rainwater collection are lined with plastic to prolong the life of the tank, prevent leaks and protect water quality.In addition to roofs, tanks can be set up to collect rainwater from concrete patios, driveways, and other impervious surfaces.Initial capacities typically ranged from 400 to 100,000 liters (110 to 26,420 US gal), today modern technology has allowed for modular and scalable applications up to millions of liters or hundreds of thousands of US gallons.

Smaller tanks such as plastic (208 liter (55 US gal) buckets) are also used in some cases.Larger tanks are often used where centralized water supplies are not available.The company recommends a 1,135-liter (300 US gal) tank for a two-person home (if a composting toilet is placed) if the area receives at least 762 mm (30.0 inches) of precipitation per year.If there is less rain (between 254-762 mm (10.0-30.0 in)), two or three 300-gallon tanks can be placed to collect more rainwater when it rains.Forecasted rainfall also affects tank size and rainfall variability; higher prices for larger tanks; intended uses of rainwater and typical consumption for those uses; area of roof drainage to tanks; required security of supply.

Most rainwater collection tanks used around the world are made from virgin polyethylene, a substance that is FDA and NSF approved for potable water storage in the United States.Other types of tanks used for rainwater storage include fiberglass, galvanized metal, stainless steel, and concrete.Each type of tank has positive and negative aspects.When polyethylene tanks are placed on the ground, algae growth is possible and due to normal UV exposure in the sun, the service life may be shortened (approximately 20 years).Very strong fiberglass tanks must undergo a specific coating process to be drinking grade.Galvanized tanks must be lined or coated to ensure potability and to prevent the inevitable rusting at any welds.Uncoated galvanized tanks will leach zinc into the stored water and are not recommended in most cases certainly not suitable for storing water for human consumption.Concrete tanks leach a more harmless substance, lime, into the stored water, and many tanks are used around the world for rainwater storage.

One way to harvest rainwater is a modular, expandable system that can be installed underground.These are an evolution of the application of geosynthetics, known as infiltration ponds, which when stacked provide a volume of void space in which water can be stored.Improved and more cost-effective industrial designs now allow theoretically unlimited storage of groundwater.