Among the areas expected to be affected are parts of the Central Business District, Ngara, Lavington, Kilimani, Westlands, Kibera, the Industrial Area and Kinoo.
The interruption will also extend to surrounding estates, impacting households, businesses and institutions that depend on the city’s water network.
According to the company, the works involve the completion of reservoir systems that play a central role in the distribution and storage of water across Nairobi.
Once finalised, the upgrades are expected to enhance water pressure, improve distribution efficiency and reduce the frequency of unplanned outages that have affected residents in the past.
Nairobi Water said the temporary inconvenience is necessary to allow engineers to safely connect and test the upgraded systems without risking damage or compromising service quality.
The company noted that such infrastructure projects are essential in meeting the growing demand for water in a rapidly expanding city.
Residents in the affected areas have been advised to store enough water in advance to last through the interruption period.
The utility also urged consumers to use the available supply sparingly in the days leading up to the shutdown to help maintain reserves within the system.
Businesses, particularly those in the hospitality and manufacturing sectors, are expected to feel the impact of the disruption, with some likely to seek alternative water sources to sustain operations.
Institutions such as schools and hospitals have also been encouraged to make contingency plans to ensure minimal disruption to essential services.
The company further indicated that water supply will be restored gradually once the works are completed, with normal distribution expected to resume after the five-day period.
However, some areas may experience delays in full restoration depending on their location within the network and water pressure levels.