Effects of roof pitch gradient and material to harvested rainwater quality

Abstract

Rainwater harvesting has untapped potential in domestic usage due to the lack of awareness and design guidelines to building sustainable roofs. Studies suggest that combinations of different roof pitch gradient and materials will affect the runoff quality. The level of contamination and contents found in the harvested rainwater will require different ways for water treatments prior to usage. The objective of this research is to identify design criteria of a building roof affecting the roof runoff quality in Kuala Lumpur. Quantitative analysis is done based on the rainwater collected from case studies with combinations of different roof pitch and materials to identify the contents and level of contamination in each of the collected sample. The result observed the best runoff quality from clay tile roof of 45°, metal roof of 15° and polycarbonate roof of 15°; whilst reinforced concrete (RC) flat roofs harvested the most contaminated runoffs. The study shows that all roof runoff quality is not up to potable standard though can be used for indoor non-potable use with minimal treatment.