Variability of Rain Water Quality due to Roof Characteristics

Abstract

Rainwater harvesting is receiving increased attention worldwide as an alternative source of drinking water. Although, some people typically consume collected rainwater without any type of disinfection, the microbial and other physic-chemical qualities of this water source can be poor. In this paper, the variability of rain water quality due to roof characteristics was investigated using some randomly collected data from both industrialized and rural areas in Gboko, Nigeria. Questionnaires were randomly administered in the rural areas to obtain data on the type of roofing materials and age of the roof. In addition, samples were also collected from both areas and examined for alkalinity, pH, NO₃⁻, SO₄²⁻, NH₄⁺, Ca²⁺, Mg²⁺, dissolved heavy metals (Fe, Cu, Mn, Zn, Ni and Cr), and total coliform (not detected). The examined parameters gave average values of alkalinity, pH, NO₃⁻, SO₄²⁻, NH₄⁺, Ca²⁺, Mg²⁺, Fe, Zn as 4.8mg/l, 7.77, 23.9mg/l, 1.2mg/l, 26.1mg/l, 120.3mg/l, 99.6mg/l, 0.12mg/l, 0.13mg/l respectively. It was discovered that, the period of rainfall, environmental factors, type and age of roofing materials have varying effects on the characteristics of rainwater. From the experimental result, the roof drainage water quality in Gboko can be used as grey water for domestic purposes but requires treatment to be used as drinking water.

KEYWORDS: Rainwater quality, Water availability, Rainwater harvesting, Variability, Roof drainage