Achieving safe, free, residual chlorination at point of consumption in emergencies

What is the humanitarian need being addressed?

Achieving adequate levels of free chlorine residual (FCR) at the point of use (POU) is a challenge faced in emergencies. It is important that this level remains safe in order to provide drinking water.

The SPHERE humanitarian standards target is 0.5 mg/L at the tap, with other guidance varying from 0.2 to 2 mg/L. But storage periods of up to 24h are not considered; during which water safety may no longer be guaranteed due to FCR decay. The challenge is how to predict the initial dose needed and monitor the poststorage target (0.2 mg/L @ 24 h) considering relevant chlorination chemistry kinetics (fast & slow demands) and field conditions (sunlight, temperature etc).

What is the innovative solution and how will it improve existing humanitarian practice?

This project aimed to work towards ensuring there are safe levels of chlorine in the water used in emergencies, thereby filling the need for a practice-oriented emergency-adapted approach, grounded on the underpinning chlorination processes taking place and novel monitoring techniques. Practitioners would know how much chlorine to dose to achieve a desired FCR target. They will also then know when such a target is not achievable and other action is required.

By identifying and incorporating significant variables that may change from site to site (water quality, ambient temperature, storage condition, etc.) into the proposed methodology, this project sought to deliver a simple and robust procedure with the potential for universal application. Also, the proposed monitoring innovation could facilitate representative sampling and continuous monitoring of supplied water through low-cost sensors.

These operational tools have the potential to serve humanitarian field staff involved in water supply interventions. The usefulness of this could be further extended through its incorporation in to curricula used by professionals working in WASH training and capacity building.

What were the grant outcomes?

The University of Victoria developed a tool to determine the required chlorine dose to attain a target free residual at a predetermined target (storage time). A model was developed and tested by acknowledging the mechanisms of chlorine degradation. It is ready for further development to ensure it can be universally applicable to different water types and contexts.

You can read the published journal article under the Tools and Research section below.