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April 14, 2024

Unchecked pollution of city’s water sources poses health risks to residents

Away from its swanky glass facades, trendy cafes and ultramodern highways, deep into its neighbourhood, Nairobi’s estates convulse in water stress, chaotic settlements and nauseating stench of open sewers.

Hundreds of houses and pit latrines in Kawangware, among other informal estates, discharge raw sludge into Nairobi River and its tributaries.

The same water from this river is used by peri-urban farmers downstream — in Njiru and Mwiki — to irrigate vegetables consumed by city dwellers.

Last month, the 
Water Kenya team traced the Nairobi waterway upstream, from Kangemi, where seemingly clean water flows unadulterated until it reaches areas in Kawangware.

Walking along the river’s bank, from Kawangware towards the city, the water becomes increasingly darker and murkier as raw sludge and debris from Gatina and Congo in Kawangware, and Sodom in Kangemi run into the river at certain points.

More contamination from garage spillage, surface runoff and effluence from surrounding buildings is released into the riverine around the central business district.

Consumers Federation of Kenya (Cofek) secretary-general Stephen Mutoro is categorical that it is criminal for anyone to discharge sewage into a waterway and blames the lapse on the county government’s poor surveillance in efforts to end the mess.

Nairobi’s sewerage infrastructure is old, having been laid over 40 years ago, and constrained in terms of capacity.

It is, thus, prone to frequent bursts, which worsen the risks of contamination of water sources.

Mr Mutoro said due to rampant contamination of water sources, urban farming needs to be licensed to curb practices such as using water polluted with sewage.

“This, however, doesn’t happen due to lack of surveillance and enforcement, which are county government responsibilities,” the Cofek boss said.

Environmental Compliance Institute director Gerphas Opondo warned that raw sewage effluent contains industrial and human waste, and other toxic substances that are harmful to health.

“The waste water also contains pathogens that settle on the vegetable leaves since the farmers carry out open field irrigation,” Mr Opondo said.

“Most of the sewage treatment plants in Nairobi rely on anaerobic treatment systems, which do not kill the chemical components contained in the sludge, thus they end up being absorbed by the crops.”

He reckons that the presence of open sewers in the city increases chances of contamination of the available fresh water resources, further dashing any hopes of relying on boreholes.

Contaminated water, according to the World Health Organization (WHO), is a breeding ground for cholera, dysentery, typhoid and diarrhoea, one of the main killers of children under the age of five.

While the factors driving the sanitation havoc in Nairobi can be described as manifold, environmental experts point to the city’s shambolic water distribution system as a big letdown.

Prof Ratemo Michieka, a veteran environmental scientist at the University of Nairobi, told the Saturday Nation that lack of access to clean water is a key factor in the use of waste water for irrigation by peri-urban farmers.

Prof Ratemo, a former National Environment Management Authority director, said many residents were admitted to hospital with cholera in the last few months, which is a pointer to sanitation deficiency.

 He added that it is time the government took public health with the seriousness it deserves.

“Most of the water pipes run side by side with sewage pipes. Contamination is likely to happen, especially during construction, when excavators hit and break water and sewer pipes,” Prof Ratemo said.

“In addition, surface runoff during the rains mixes with clean water in the burst pipes, resulting in contamination.”

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