Water harvesting, a LID strategy, is the collection and storage of rainwater. It is both cost-effective and eco-friendly; however, state laws may dictate water harvesting use and ownership.
Examples of water harvesting include:
- rainwater caught coming from a rooftop
- stormwater collected from a land surface
- dew captured with a net
Harvested water may be collected from a variety of sources including:
- rooftops
- local catchments
- seasonal floodwaters from local streams
- drains
- roadways
Urban rainwater harvesting measures provide considerable benefit to both the wastewater subsystems and the water supply by:
- reducing/eliminating the amount of stormwater that enters the sanitary sewer systems
- providing clean water which reduces the demand on water distribution systems
- reducing/eliminating pollution of freshwater bodies caused by stormwater runoff
Water harvesting provides an independent water source, when water restrictions are in place, and can be used to supplement water supplies in developed countries. Water harvesting also:
- reduces or eliminates flooding in low-lying areas
- makes water available when a drought occurs
- reduces the demand on wells
- maintains/prolongs groundwater levels
The advantages of harvesting rainwater include:
- It is environmentally friendly (i.e. saving clean potable water for drinking and cooking, instead of washing cars and watering the garden).
- It reduces the use of groundwater.
- It is a free, clean source of water that can be used to reduce water bills.
- A rainwater collection system is easy to install using existing rain gutters.
- It can be used for a variety of purposes since it is relatively pure and free of toxins/minerals.
- Since it is free from chemicals, it is great for agricultural irrigation.
- By reducing runoff during heavy rainfall, flooding and soil erosion is decreased.
When rainwater is captured, it may be directed to a location for storage such as:
- storage barrels or tanks
- cistern
- deep pit such as a borehole, shaft or well
- aquifer
- reservoir
When rainwater is stored, it’s important to have mosquito management measures in place. Storage barrels and tanks, often used to store runoff from smaller structures such as houses and sheds, generally hold between 55 to 200 gallons and should be manufactured with food-grade materials. Cisterns and deep pits are used to collect water from larger buildings. All storage systems must make provision for overflow by funneling the water to a location that will not cause safety issues or foundation problems.
Water can be harvested to serve a variety of purposes which may include:
- drinking water when appropriate treatment measures are used
- irrigation
- watering livestock
- reduction of stormwater discharges, urban flooding, and the overloading of sanitary sewer treatment plants
- increase groundwater recharge
- long-term water storage
- reduction of seawater ingress in coastal areas
The CDC issues warnings concerning the use of rainwater, especially as a potable water source, stating that water intended for drinking needs to be filtered, disinfected and tested regularly.
Interestingly enough, rainwater can also be collected using solar PV panels which are able to gather most of the rainwater that falls onto them. This water can easily be converted to quality drinking water using simple filtration and disinfection processes. This makes it possible for solar PV plants to generate income, even in cloudy areas that have high rainfall, through the sale of bottled potable drinking water.
When rainwater is collected in large tanks and cisterns, it can be used as-is without the need for filtration or purification. A multi-layered polyethylene (RPE) material, such as BTL’s AquaArmor, can be used to catch and store rainwater. AquaArmor is the strongest, most reliable catch basin liner on the market today. Visit BTLLiners.com/AquaArmor to learn more. AquaArmor products can also be used to cover the stored water to prevent evaporation.
