Collecting Rainwater from Roofs – On the House

Collecting Rainwater from Roofs

By on April 16, 2017

Saving rainwater isn’t just about reducing water bills. It’s about conserving natural resources. With so much water coming out of the sky during the first part of this year, now is the ideal time to consider harvesting rainwater from roofs.

“West Coast areas that are normally dry have seen incredible rainfall amounts so far in 2017,” says Tim Gentry, vice president of technical services at DaVinci Roofscapes. “The Sacramento area was drowning in more than 17 inches of rain during the first two months of the year. Imagine the potential for saving that rainwater for use later during the dry season.”

Gentry points out that collected rainwater can be used for a variety of home tasks, including:

  • washing cars
  • watering plants
  • cleaning

“Water harvesting is an easy, positive way to help the environment. As rainwater slides off a polymer, metal, ceramic or real slate sloping roof into collection barrels, it’s safe for secondary uses like garden irrigation, doing laundry or flushing a toilet.”

Every Drop Counts

According to Gentry, if enough people implemented rainwater harvesting techniques at home, it could help reduce demand on existing water supply in their areas.

rain barrel, harvesting water“Look at a city like Macon, Georgia,” says Gentry. “They had 6.6 inches of rain in the first two days of 2017. That amount broke all kinds of records. If people had harvested even a portion of that water, then it would have helped reduce run-off and erosion. The community could use the saved water for everything from fire protection services to filling outdoor public pools.

“Whether collected in barrels or through pipes going directly into cisterns for use and storage, gathered rainwater can make a big impact. According to, for every inch of rain that falls on a ‘catchment area’ of 1,000 square feet, approximately 600 gallons of rainwater can be collected. Now, remember that Macon received 6.6 inches of rain. That number means there was a potential to save almost 4,000 gallons of water! That’s quite a strong contribution to the water supply for a homeowner.”

Barrels of Rainwater

At the Absolute Green Home in South Salem, N.Y. (which won the “Best Renovation of the Year Award” in 2015 from Green Builder® Media), when it comes to rainwater collection, the owners have their neighbors over a barrel. Literally.

There are four rainwater collection barrels dangling from key roof slopes on the renovated home. Each barrel encourages water to slide gently into it from the Bellaforté Slate polymer roof overhead via a chain. Once filled, the unfiltered water in the barrels can be used for exterior watering of plants and gardens.

This rainwater collection system was just one of many strategies that Sylvain Coté, project architect and coordinator with Absolute Green Homes, Inc., incorporated into the home. Starting from the top down with a composite slate roof, the 1932 beach home has earned three green designations: ENERGY STAR® Certified Home, LEED Platinum Certified Home and Home Energy Rating System (HERS) Certified Home.

rain barrel, harvesting water

Expansive Rain Harvesting Effort

When the Hageman family constructed their 5,300-square-foot Green Life Smart LifeTM home in 2009, they had the goal of reducing landscaping irrigation demand by at least 50 percent by using harvested rainwater. For their Rhode Island home the family installed EcoBlend Slate tiles from DaVinci Roofscapes to help them reach their goal.

“One of the key reasons we selected our DaVinci synthetic slate roof was because the tiles do not release toxins which could potentially run off into the water system,” says Hageman. “The rainwater collected from the roof over our home travels to an interconnected gutter system that directs all the water to our 5,000-gallon underground storage tank. We use the pure water as needed to support our landscaping efforts.”

Synthetic roofing tiles from DaVinci have inorganic pigments permanently bound into the polymer tiles, and meet Proposition 65 protocols. This California test (The Safe Drinking Water and Toxic Enforcement Act of 1986) certifies that products do not release or discharge toxins into the water.

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