This lack of capacity and maintenance results in frequent blockages which cause flooding of property, public areas and rivers with sewage. Cracked sewers permit part of their contents to enter the surrounding ground with potential risks of contamination of groundwater and defective water distribution systems. Where surfacewater sewers exist it is common for them to receive illegal discharges of foul sewage. The lack of adequate solid waste collection services can frequently lead to the deposition of household and industrial refuse in drainage channels and open sewers with consequent blockage problems and release of pollutants into the water cycle. High ambient temperatures amplify pollution effects.
Solutions depend upon stakeholder participation in any remedial work.
Lack of financial and human resources often constrain remedial work, the need for which is well recognized by the authorities. However, they can be responsible for significant pollution problems which if unrecognized may hinder the attainment of aquatic environment improvements. In the specific case of urban agriculture for food production the use of fertilizers and pesticides can result in significant non-point sources of water pollution which may make the water unsuitable for potable supply without complex treatment. In consequence they risk being economically and technically unsound. They are, however, appropriate as a starting point in pollution control.