Rainwater HarvestingAll freshwater sources on land essentially originate from rainwater, which falls to the ground as part of the water cycle. In essence, rainwater is distilled water, having had all impurities removed during the evaporation and condensation process. However, depending on the levels of atmospheric pollution, rainwater may wash out contaminants as it falls through the air. This includes pollutants such as carbon dioxide, which transforms rainwater into carbonic acid – better known as acid rain. That is why the air is always clean and fresh after it has rained; however, as the pollutants are contained in the rain drops, the rainwater is not.
Harvesting rainwater involves channeling and collecting rainwater for future use. Rainwater is typically collected from rooftops via gutters, which lead to a storage tank, but it can also be collected from any impermeable surface. There are a number of rainwater harvesting systems available on the market, ranging from the simple and affordable, to the complex and costly. Rainwater can be harvested for many uses, including watering plants and irrigation, washing pets and cars, flushing toilets, or for providing drinking water for pets and livestock. Besides the pollutants that rainwater absorbs from the atmosphere, rainwater may also pick up other impurities as it washes over surfaces on the ground. Rainwater may wash debris such as dirt, dead leaves, dead insects, and bird droppings from rooftops and gutters into the rainwater tank. Consequently, harvested rainwater is generally not recommended for human consumption without some form of treatment or precautionary measures to remove potential contaminants.
However, there are a number of precautions that can be taken to remove impurities while harvesting rainwater. By fitting your guttering with a suitable water filter mechanism to filter out larger particles of debris and sediment, these impurities can be prevented from entering the rainwater collection tank. Some commercially available rainwater collection systems include a first-flush device, which eliminates the initial torrent of rainwater that washes off most of the dirt and grime from roof and gutters, and then diverts the rainwater to the storage tank once the initial spurt of dirty water has been flushed from the system. However, these precautions will not remove micro-organisms and bacteria that may be present in the rainwater tank, which could pose a serious health risk to humans. Furthermore, the rainwater stored in the tank may have an unappealing color, and it may also have a foul taste and odor due to impurities that may be dissolved in the water. Consequently, if the water is to be used for human consumption, more stringent water purification methods will need to be implemented to remove taste and odor contaminants, and to ensure that the water is free from pathogens.
But like any source of fresh water, with suitable treatment, the water can be rendered safe for drinking. Water purification methods to remove contaminants and micro-organisms can include drinking water filters, chemical disinfection, or a combination of water purification methods. By implementing suitable measures, one can tap into a valuable free source of water that can not only be used for domestic purposes around the home and garden, but can provide a source of drinking water as well.