Research article

Assessment of the corrosiveness of the water in the distribution line from intake to consumer outlets in Malawi

¹Kabwazi MM, ¹Mwenechanya J, ¹Moyo BHZ and *²Mumba PP

¹Natural Resources Management Department, Malawi

²Basic Science Department, Lilongwe University of Agriculture and Natural Resources, P.O. Box 219, Lilongwe, Malawi

*Corresponding Author E-mail:  mumbap01@yahoo.com

Accepted 26 March 2015

Abstract

A study was carried out to assess the water quality in the distribution pipes in Malawi. In particular the study was aimed at testing the corrosiveness of the water using the Langelier Saturation index (LSI). Water hardness and total alkalinity were both lowest (p<0.05) at the intake but higher levels were recorded at the other three points but in each set values did not vary significantly from each other. The Total Dissolved Solids were also lowest at the intake but the values increased steadily towards the consumer’s outlets. The lower values at the intake could be due to natural sources and the chlorination. There was a slight increase at and after treatment with chlorine that was attributed to the presence of ionic metals that might have dissolved from the pipe. The LSI values obtained at four sampling points from the intake to the consumer outlets; -2.5, -2.2, -6.5 and -2.1 suggested that the water in the distribution line was corrosive all the way to the consumers. This could be a health risk to the consumers and may also affect the lifespan of the pipes themselves. It is therefore recommended that frequent corrosion assessments should be done so that the levels of corrosion in the pipe distribution systems are constantly monitored and checked.

Keywords: Corrosion, distribution system, water quality, water treatment