Maintenance Corner | September 2022 | “Residential Rainwater Collection Systems”

If someone offered you free water for your yard and household needs, it would be pretty hard to turn that deal down. It's there for the taking if you install a rainwater collection system.

Rainwater collection has been in use for thousands of years, but it's becoming an essential feature for a sustainable home. Collecting your own rainwater lessens your need for treated municipal water. In the event of an emergency, your collection system would be able to provide you with an ample amount of water for washing and other non-potable water needs.

Types of Residential Rainwater Collection Systems

The concept of a residential rainwater collection system is pretty simple: gather, or catch, rainwater and store it for later use. You can catch rainwater from your roof or from the ground.

Roof Catchment

Your roof accounts for a large surface area, and when it rains, this water is typically routed through a system of gutters and pipes and dumped unceremoniously into your yard, where it washes away valuable topsoil.

Roof catchment systems, which are the most common type for residential applications, collect this water by routing it through a system of gutters and pipes into a rain barrel, usually located on the ground level.

Starting with a new 55-gallon plastic barrel, available for around $130 to $160, you can build your own DIY rain barrel collection system for under $200. An in-line downspout diverter, a plastic or metal device, sends up to 40-percent of the water into the rain barrel (the rest goes on the ground or in a catchment system).

The choice of roofing material is extremely important as some types can contaminate the water, such as those with coatings or metallic finishes or asphalt.

Acceptable roofing materials for catchment systems include aluminum, tiles, and slate or galvanized corrugated iron.

Ground Catchment

A ground residential rainwater collection system is a more simple approach than the rooftop version and offers the possibility of a wider catchment area.

Water may be collected via drain pipes or earthen dams and stored above or below ground in tanks. The quality of water may be lower at the ground level, rendering the captured water suitable for landscaping needs only.

What to Use Collected Residential Rainwater For

  • Landscaping
  • Car washing
  • Laundry
  • Adding to toilet tanks for flushing
  • Washing walkways
  • Cleaning driveways

Residential Rainwater Safety Considerations

Rainwater collected from the roof or ground is generally considered to be non-potable. Do not consume collected rainwater. Boiling collected rainwater will not render the water safe if, for example, it contains chemicals or metals from the roof or herbicides or pesticides from the ground.


Rainwater systems range from extremely basic, such as a barrel beneath a downspout, to highly technical, including a pump and filtration system.

The cost varies accordingly, from as inexpensive as a $200 do-it-yourself system with a 55-gallon barrel up to $20,000 or more for a complex roof catchment system. Check rainfall statistics in your area to determine if a catchment system is a worthy investment.

Pros and Cons of Residential Rainwater Collection Systems


  • Free water reduces water bills

  • Auxiliary water storage system

  • Reduces flooding around property


  • Possibility of mosquito larvae

  • Algae develops in sunlight

  • Rain barrels and cisterns large and unsightly

If you live in a rural area and lack access to municipal resources, rainwater catchment can greatly enhance your well-water source, or if you live in a city, reduce your dependence on municipal water. Other benefits of a residential rainwater collection system include the reduction of stormwater runoff and lower water bills. Rainwater systems are generally pretty flexible, allowing you to reconfigure them and sometimes even relocate them to a new home.

Keep in mind, however, that residential rainwater collection systems require regular maintenance, such as cleaning the roof surface, piping, and storage container to prevent the water from becoming contaminated.

Also, standing water is a natural mosquito breeding ground, so you must use netting or other devices to keep them out. Algae is another concern. Sunlight accelerates the growth of algae, so it's best to keep the water collection system covered or shaded.

Cisterns can be unsightly. It is possible to camouflage them, and if you are concerned about the aesthetic impact, then opt for an underground version.

Before installing a residential rainwater collection system, check with your local building code; in many cases, you won't need a permit if you're only using the water outside, but if you pipe it into your home for flushing the toilets or laundry, you'll most likely have to deal with the building department and install separate lines for gray and city water.


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