There are several rules for treatment of wastes in the industries, but disposal of untreated wastewater into drains and, subsequently, into the city's major streams is very common, thus posing a potential health and environmental risk to the people in Blantyre and downstream. Other sources of water pollution in the city such as run-offs from domestic and agricultural activities and vehicle emissions have been identified. Previous studies have indicated substantial heavy metal pollution in the city's water bodies including streams. Major changes in industrial activities have occurred in the city including a decrease in volumes of wastewater generated by the David Whitehead company, which used to be a major contributor of wastewater effluent in Makata industrial area; change of ownership and wastewater management of Cold Storage Company; closure of the Shire Bus Line; doubling of wastewater generation from both Carlsberg and Chibuku Products due to increase in production and installation of some industrial pre-treatment plants such as at Chibuku, Plascon and Dulux.