The tangled webs we weave… mapping and finding water pipes in the city

Can you guess which one of these pipes is connected to the city’s water supply? Turns out, no one can.

In a water-stressed emerging megacity like Dar es Salaam, you can find some very interesting approaches to getting piped water into a home. I am here working on an evaluation of a large water supply project, and we are trying to use automated pressure loggers to measure the frequency of water outages (or, in many areas, the frequency of the water actually coming on).

You can immediately understand why so little monitoring of urban water systems is performed in a water sector that is still very much focused on rural villages. There are so many different strategies to getting enough water in a city that our traditional approach of visiting “the water point” and interviewing the responsible person does not apply here.

Residents who can afford it buy massive tanks to ensure a steady supply of water during prolonged outages.

In order to install the logging device, we needed to find a tap that connected directly to city water with no tank in between. A tank would mask the pressure drops we wanted to detect and measure. But much of the action happens underground and not many people have interest in where the pipes go as long as they can get water from them.

This tap connects to two sources!

When the water stops flowing from one pipe, it’s often easier to just lay down another pipe. Each one of these junctions is an opportunity for leaks to get out and contaminants to get in, contributing to poor water quality even if the water was clean when it left the treatment plant.

In order to start addressing the unreliability of water service and poor water quality in rapidly urbanizing areas, we need to start identifying and tracking these problems better. The automatic pressure loggers are one solution, but there is also a lot more we can do in terms of mapping the informal water distribution networks and learning about the different strategies city people use to deal with an uncertain water supply. This is urgently needed to help design programs aimed at reaching the most vulnerable and water stressed people in urban areas around the world.

Success! An automated pressure logging device installed in Dar es Salaam to measure outages. The devices will remain on each tap for a week before rotating to a new location. The data will provide a detailed snapshot of water availability, such as average hours of service per day, at the level of the entire city.