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Using Metal Roofing for Rainwater Collection

Rainwater Catchment Information & Recommendations

Rooftop rainwater collections are quickly becoming a popular choice for builders, both commercial and residential, seeking sustainable, eco-friendly water harvesting solutions. Metal roofing provides the optimal catchment surface for rooftop rainwater harvesting systems.

Rainwater Harvesting

For the majority of rainwater collection, a roof acts as the primary catchment area. A roof provides a wonderful surface for this purpose, especially a metal roof with appropriate paint systems.

Rainwater collection is an important part of the LEED process to help reduce runoff volume, and improve water quality on sustainable sites. To effectively capture this water for redistribution, a collection system such as the roofing and gutter systems on a project must capture up to 25% of the water from impervious or hard surfaces. This water can then be filtered and reused in the buildings sustainable water system, or released into a public wastewater treatment facility. 

Designing and maintaining metal roofing that incorporates a collection system can be simple. The design of the roof needs to be durable to withstand the weight of heavy rain or snow and there must be an easy path for the water to follow.  Bridger Steel manufacturers a variety of panels that will hold up to all weather conditions and the smooth surfaces make it easy to clear debris and dust.

When planning to use a roof as a catchment area, understanding the components that you need to consider will help the success of your build.

Roofing Material

While a number of base materials like asphalt, slate or tile roofs can be used as rainwater collection catchments, metal is often the preferred system. This preference has less to do with the base material and more to do with the potential contaminants that may grow on the material itself. Metal roofs are often coated in anti-microbial paint systems, and shed larger materials easily without the range of cracks and crevices for materials to adhere to.

The Roof Slope

The angle of your roof, or slope, will determine the speed and rate at which water will leave your catchment area. A steep sloped roof will shed water quickly, along with better removing debris or other foreign materials. A higher slope also performs better as a catchment area by preventing stagnant water buildup and possible contaminants from affecting your storage.

Calculating Water Catchment

Understanding how effective your rainwater collection system will be using your roof can be determined by using the following formula:


Harvested Water (gallons) = Catchment Area (sq ft) x rainfall depth (inches) x 0.623 (conversion factor)

Bridger Steel provides eco-friendly builders with the ideal rainwater catchment surface  - creating lasting beauty and conserving resources with safe, easy and effective metal roofing.

For more information or advice, contact a Product Specialist

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