Steps to Harvesting

The Collection, Conveyance and Storage of Rainwater for Later Use

Commonly rainwater harvesting systems are constructed of three primary segments; (1) a collection method, (2) a conveyance component and (3) a storage facility. Rainwater harvesting collection, conveyance and storage systems can be incorporated into almost any existing site or building, although it is often easier to incorporate a rainwater harvesting system into new construction.

1. A suitable catchment surface: generally a simple structure such as hard roofs and/or gutters that direct the rainwater through a conveyance component into storage. Roofs are ideal as catchment areas as they easily collect large volumes of rainwater. The amount and quality of rainwater collected from a catchment area depends upon the rain intensity, roof surface area and type of roofing material. For a 1,000 square foot roof, about 623 gallons can be collected, per inch of rainfall, regardless of pitch. Water quality from the roof catchment is a function of the type of material used on the roof, climate conditions, and the surrounding environment. If the collected rainwater is for potable use, select and use materials that will not leach toxins into the rainwater under normal or acid rain conditions. The roof material should be both non-toxic and inert.
2. Conveyance components: required to transfer the rainwater from the roof catchment to storage. Conveyance is usually accomplished by connecting roof drains and piping from the catchment area (or roof top) to one or more downspouts that transport the rainwater through a filter system to storage in tanks for reuse or recharge.  Also includes any screening devices to prevent debris and other material from entering the storage tank(s); see 3-6 below
   
3. Gutter filter (optional): especially useful where excessive tree coverage might lead to rapid accumulation of debris and clogged gutters
   
4. Rain heads (optional): combine with gutter filters/screens to minimize debris accumulaton
   
5. Water diverters (optional): also known as first-flush devices, used to divert the initial flush of water to waste, to help minimize contamination of stored water
6. Tank screen: additional debris screening and serves to prevent mosquitoes and other pests from breeding or entering the storage tank(s)
   
7. Storage containers or cisterns: store rainwater so it will be available when needed. Depending on the space available these tanks can be constructed above grade, partly underground, or below grade. Various types of rainwater storage containers can be found in use. They include cylindrical ferrocement tanks (reinforced steel and concrete), mortar jars (large jar shaped vessels constructed from wire reinforced mortar), single and battery (interconnected) tanks made of either galvanized steel, concrete, ferrocement, fiberglass, or polyethylene, or they could be made of wood, metal, or earth. The polyethylene tanks are the most common, and easiest to clean and connect to the piping system. Storage tanks must be opaque to inhibit algae growth. They should be located as close to supply and demand points as possible to reduce the distance the water is conveyed.
8. Overflow fittings: should be screened to prevent insect entry; proper engineering of overflow can also allow multiple tanks to be filled and drained as a single unit; hose or drainage pipe can be connected to direct water to a suitable location away from a building's foundation
9. Make-up water (optional): automatically fills tank to a predetermined level if they become empty during prolonged droughts; adequate cross-connection prevention devices MUST also be installed according to local building codes

10. Pump system: for efficient distribution, should be sized for the expected water demand

11. Filtration: Fit a purpose designed RAINWATER FILTER after the pump to help reduce residual sediment, color and odor.
12. Water Level Monitor (optional): Install a level indicator to help monitor water usage. Wireless systems are most convenient and display a reading inside the home.