Rain barrels collect and store rainwater runoff, typically from a home’s roof and downspout. Rainwater harvesting is an ancient practice seeing renewed interest as a method of environmental stewardship and economic savings. The primary motivation for homeowners is to capture a free, readily available water source, reducing reliance on municipal water supplies and lowering monthly utility bills. This conservation effort also helps mitigate environmental concerns by decreasing stormwater runoff, which can contribute to erosion and carry pollutants into local waterways.
Practical Applications for Outdoor Use
Collected rainwater is naturally soft and free of chlorine and other chemical treatments found in tap water, making it well-suited for many outdoor tasks. The most common and safest application is irrigating landscapes, including trees, shrubs, and lawns. Using soft rainwater for this purpose can be beneficial for plant health and may also help maintain a balanced soil pH.
The water is also excellent for various cleaning tasks around the property, where purity is not a concern. This includes washing vehicles, as the lack of minerals in the soft water minimizes streaking and water spots. Rain barrel water can be used for cleaning tools, rinsing off muddy boots, and washing outdoor furniture, patios, and decks.
Another safe use is to replenish non-recreational water features like birdbaths, fountains, or decorative ponds that do not contain fish or other sensitive aquatic life. For all these applications, the water is being used externally, and human contact is minimal, making them efficient and risk-free ways to utilize the stored supply.
Understanding Water Quality and Safety Precautions
While collected rainwater is free, it is not sterile and must be considered non-potable without treatment. The water picks up various contaminants as it travels over the roof surface and through the downspouts. These contaminants fall into two main categories: chemical and biological.
Chemical pollutants include heavy metals like zinc, lead, and cadmium, which leach from roofing materials, gutters, and flashing. Asphalt shingles can be a source of lead, while galvanized metal components contribute zinc and cadmium. Airborne particulates and deposited materials, such as pesticide residues and polycyclic aromatic hydrocarbons (PAHs), are also washed into the barrel during a rain event.
Biological contamination primarily comes from animal waste, such as bird droppings, deposited on the roof. This fecal matter introduces pathogens, including bacteria like E. coli and other fecal coliforms. These microbes multiply within the stagnant water, posing a risk if the water is ingested or contacts open wounds.
To improve water quality, install a first-flush diverter, which redirects the initial, most contaminated flow away from the barrel. Sealing the barrel with a fine mesh screen over the inlet prevents debris from entering and stops mosquitoes from breeding. Regular cleaning of the barrel is necessary to prevent sludge accumulation and reduce microbial growth.
Restricted and Unsafe Uses
Due to the presence of pathogens and chemical contaminants, untreated rain barrel water should never be used for several activities. The water must not be used for any purpose involving human ingestion or full-body contact.
This includes:
- Drinking, cooking, rinsing fruits or vegetables, and making ice.
- Personal hygiene activities such as bathing, showering, or brushing teeth.
- Filling recreational water bodies, including swimming pools, hot tubs, or wading pools.
- Using the water in indoor humidifiers or nebulizers, as this aerosolizes contaminants for direct inhalation.
When irrigating a vegetable garden, avoid applying the water using overhead sprinklers, which can splash contaminants onto edible parts. It is safest to avoid using this water on root vegetables, leafy greens, or any crop where the harvested portion contacts the soil. If used on edible plants, the water should only be applied directly to the soil via drip irrigation, and the produce must still be washed thoroughly with potable water before consumption.