With over 3 million people, the city of Nairobi faces several water supply and pollution challenges that are exacerbated by burgeoning slums and informal settlements. This paper analyzed the existing status of urban water-pollutant flows in Nairobi city. A box-flow model was developed to identify the most important pollutants in the urbanized area. Total nitrogen (N) and phosphorus (P) loadings in water were used as indicators for water pollution. The paper found that the commercial and industrial water users are the major emitters of N (45,301 ton/yr) to the environment. This was attributed to Nairobi’s majority agro-based industries which release nitrogen rich organic-compounds into the system boundary. Households were major sources of P (2,663 ton/yr) to the environment. Most of the P in wastewater results from the P-rich detergents used for cleaning and washing at the household level. Investment into improved sanitation and wastewater treatment technologies is recommended to ameliorate the amount of nutrient flows into water bodies. Further, prohibiting use of P-rich detergents is important in reducing P emissions. These actions are needed to guarantee safe drinking water supply to the city in order to keep pace with the fast emergent population. An effective multi-sectoral approach to environmental conservation can provide higher sustainability in the long-term.

Nitrogen, phosphorous, water flows