Rainwater harvesting involves collecting and storing precipitation runoff, typically from a rooftop, for later use in the landscape. This practice offers a direct way to conserve municipal water resources, which is especially helpful during periods of drought or restricted outdoor watering. Since rainwater is naturally soft and free of the chlorine and salts found in treated tap water, it tends to be beneficial for garden plants and soil health. Utilizing a rainwater collection system can also reduce utility expenses and mitigate stormwater runoff, which helps prevent soil erosion and overloading of local drainage systems.
Selecting the Right Collection Equipment
The choice of storage container depends on the gardener’s needs, with rain barrels and cisterns as options. A rain barrel is usually a smaller container, often between 50 and 80 gallons, designed for residential use near a single downspout. Cisterns represent a much larger storage capacity, sometimes thousands of gallons, and often require more complex installation. For most home gardeners, a standard rain barrel provides sufficient volume for watering small plots and container plants.
Several accessory components are necessary to ensure the system functions cleanly and safely. A downspout diverter is installed directly into the gutter system to channel water into the barrel while allowing excess water to bypass the barrel when it is full. A fine mesh screen or sealed lid is placed over the inlet to prevent leaves and large debris from entering the water, which also serves the important function of blocking mosquito access. Some systems incorporate a first-flush diverter, which automatically sends the initial, dirtiest water—containing roof debris and atmospheric pollutants—away from the main storage barrel, improving the overall water quality.
Consideration of barrel material is important, with food-grade plastic barrels being a common choice because they are durable and will not leach unwanted chemicals into the collected water. Metal containers, while long-lasting, can potentially leach metals, which might be a concern depending on the roofing material and water acidity. Regardless of the material, elevating the container slightly on a stand or blocks is recommended to improve the water pressure for accessing the spigot.
Setting Up Your Rainwater Harvesting System
Site selection prioritizes a location near an active downspout and the area where the water will be used. The ground beneath the barrel must be level and stable, as a full 55-gallon barrel can weigh over 450 pounds and an uneven base risks tipping. Preparing a solid foundation using concrete blocks or pavers is necessary to distribute this significant weight and provide the desired elevation.
After preparing the base, the downspout must be modified to accept the diverter system. This requires cutting a section of the downspout at the appropriate height to align with the barrel’s inlet. The diverter is then secured to the downspout, and a flexible hose or elbow connects the diverter outlet to the screened inlet on the rain barrel. This connection allows water to flow efficiently into the barrel once rainfall begins.
Managing the overflow mechanism is an important step to protect the home’s foundation from water damage. An overflow hose or pipe must be attached near the top of the barrel, typically 2 to 3 inches below the rim, and directed away from the house. This pipe should channel excess water at least 10 feet away or into a suitable drainage area, like a rain garden or storm drain connection, ensuring that the water does not pool near the foundation.
Ensuring Water Quality and Proper Usage
While collected rainwater is excellent for plants, it is considered non-potable because it is untreated and can contain contaminants picked up from the roof surface. These potential pollutants include heavy metals from roofing materials, bacteria from bird droppings, and accumulated atmospheric dust. Consequently, harvested water should not be used for drinking or any other activity that risks ingestion.
For gardening, the water is safe, but caution is warranted when watering edible crops. If using the water on vegetables and herbs, it is recommended to apply the water directly to the soil around the plant base rather than spraying the edible parts, which minimizes contact with potential contaminants. Washing all harvested produce thoroughly with potable, treated water before consumption is a necessary safety practice.
Ongoing maintenance is required to keep the stored water clean and the system functional. A sealed lid and fine mesh screen are the most effective means of preventing mosquitoes from breeding in the standing water, as they cannot access the water surface to lay eggs. To control algae growth, which is accelerated by sunlight, the barrel itself should be opaque and ideally placed in a partially shaded location. Periodically emptying and cleaning the barrel, especially before winter storage in cold climates, helps remove sediment buildup and maintains water quality.
Addressing Regulatory and Safety Concerns
Before installing a rainwater harvesting system, it is necessary to check local municipal ordinances, state regulations, and homeowner association (HOA) rules. Some jurisdictions impose restrictions on collection capacity, often limiting residential systems to a maximum volume, such as 110 gallons. HOAs, even if they cannot ban rain barrels outright, may enforce specific guidelines on their placement, appearance, and proximity to property lines.
Securing the rain barrel is important, as a full, unsecured barrel poses a tipping hazard, especially for children or pets. Barrel stability is achieved by ensuring a level foundation and sometimes by strapping the barrel to a wall or structure. The overflow system must also be properly managed to prevent water from pooling near the home’s foundation, which can cause structural damage.