Rain Water Harvesting
How Does Rain Water Harvesting Work
There are a number of rainwater harvesting systems ranging from simple to complex industrial systems. Generally rainwater is harvested from the roof of a building. The rate at which water can be collected depends on the plan area of the system, its efficiency and the intensity of rainfall.
Roof catchment systems channel rainwater that falls onto a roof into storage via a system of gutters and pipes. This in-built collection system filters out leaves and other debris and directs water to a vessel (an overground or underground tank). From here the water is pumped to the property for non-potable use. In the event of harvested water depletion the system switches automatically to a mains supply for backup. When the harvested store has been replenished the system will revert back to using harvested water.
Overground tanks are placed into basements or outside buildings where underground tanks are undesirable. Overground systems can offer more cost effective solutions as they do not require excavation of groundworks.
Underground tanks are available in a variety of sizes and shapes to accommodate the need of the user.
Header tanks differ from standard systems, whereby the harvested rainwater is pumped to a "header tank" in an attic and the services are drawn from there.
The amount of water available for collection depends upon local average rainfall, roof size and drainage efficiency and the efficiency of the filter being used. Multiplying the catchment area of the roof in meters squared by the average rainfall in millimeters, the drainage factor and filter efficiency gives the total annual rainwater yield in liters.
Tank vary in size. Small tanks can hold up to 2560 liters of water, larger tanks can hold 12,000 liters of water.
This schematic shows an overview of a basic rainwater harvesting system. Rainwater is collected from roof and is filtered before it is stored in the underground storage tank. From here it is pumped out of the tank for non-potable use like irrigation, laundry and toilet flush.
Roof catchment systems channel rainwater that falls onto a roof into storage via a system of gutters and pipes. This in-built collection system filters out leaves and other debris and directs water to a vessel (an overground or underground tank). From here the water is pumped to the property for non-potable use. In the event of harvested water depletion the system switches automatically to a mains supply for backup. When the harvested store has been replenished the system will revert back to using harvested water.
Overground tanks are placed into basements or outside buildings where underground tanks are undesirable. Overground systems can offer more cost effective solutions as they do not require excavation of groundworks.
Underground tanks are available in a variety of sizes and shapes to accommodate the need of the user.
Header tanks differ from standard systems, whereby the harvested rainwater is pumped to a "header tank" in an attic and the services are drawn from there.
The amount of water available for collection depends upon local average rainfall, roof size and drainage efficiency and the efficiency of the filter being used. Multiplying the catchment area of the roof in meters squared by the average rainfall in millimeters, the drainage factor and filter efficiency gives the total annual rainwater yield in liters.
Tank vary in size. Small tanks can hold up to 2560 liters of water, larger tanks can hold 12,000 liters of water.
This schematic shows an overview of a basic rainwater harvesting system. Rainwater is collected from roof and is filtered before it is stored in the underground storage tank. From here it is pumped out of the tank for non-potable use like irrigation, laundry and toilet flush.
