Water points in Juba, South Sudan Water points in Juba, South Sudan Photo credit: Petterik Wiggers/Hollandse Hoogte
Innovating humanitarian emergency water supply: the Clarifier Kit for Emergencies
by Caetano Dorea April 2016

Emergency water treatment kits are often designed to favour water quality over the quantity produced. While quality is important, water treatment in a humanitarian setting is largely based on the premise that the transmission of water and excreta-related diseases in emergencies is as likely to be due to the lack of sufficient quantities of water for personal and domestic hygiene as to contaminated water sources.Hence, in most cases the quantity of water supplied should be prioritised over its quality, as recommended in the Sphere standards, while simultaneously ensuring a safe water supply that is both free of pathogens and aesthetically pleasing (i.e.visually clear, no taste, no odour, etc.). In other words, a larger quantity of relatively good (safe)-quality water is better than a small quantity of very high-quality water.

Many of the water purification kits currently available use treatment processes (i.e. filtration by sand, activated carbon or membranes) that are not always compatible with field conditions in emergencies and can be expensive. In nonemergency situations, such techniques are typically used as a ‘polishing’ treatment once the bulk of the particulates in the water has been removed. When confronted with very turbid (i.e. ‘cloudy’) water, as is typical in emergency contexts, such filtration-based systems suffer from frequent clogging, and fail to provide adequate amounts of safe water. As such, many ‘innovative’ processes developed by the private sector turn out to be efficient in the removal of particular contaminants in controlled conditions, but are not effective in practice. This is partly due to the focus on high-tech solutions that do not take into consideration the operational realities of humanitarian assistance. This problem has been attributed in part to the lack of communication between manufacturers and relief agencies. While humanitarian workers can feel that private sector innovations do not adequately address their requirements, private sector companies hold the view that humanitarian organisations are not good at communicating what they want, and are often driven more by donor requirements than by real needs.

The CLARKE project

One of the objectives of drinking water treatment is the reduction of turbidity. Naturally occurring particles in suspension give water its turbidity or cloudiness. Reducing turbidity not only makes the water clearer, but more importantly it improves the efficiency of the final disinfection step which ensures that the water is safe to drink. If turbidity is high, the efficiency of disinfection can be compromised because some of the microorganisms are sheltered from the disinfectant by the particles. The simplest way to remove particles is to let them settle under the influence of gravity. The problem here is that the smaller the particle is, the longer it takes for it to settle.Moreover, in drinking water treatment the particles of concern are usually very small. For this reason, chemicals known as coagulants are used to bring such minute particles together, increasing their size and settling velocities into what are known as ‘flocs’. The removal of such flocs from water is done in sedimentation basins, also known as settlers or clarifiers. While both coagulation and inclined plate settlers are commonly used in conventional water treatment, these two techniques have never been applied to emergency water treatment together. Inclined plate settling is a clarifier variant that allows for increased particle removal efficiencies at higher flow rates within a smaller footprint. Combining these two techniques (i.e.coagulation and inclined plate settling) in one system allowed us to develop a fit-for-purpose humanitarian water treatment system: the Clarifier Kit for Emergencies (CLARKE).


The CLARKE project was a collaboration between NGOs (Oxfam and RedR India), academia (Université Laval) and the private sector (Aquaplus Ltd.). Oxfam’s humanitarian experience helped the partners identify the key constraints and criteria the plate settler needed to address; Université Laval had the research and technical capacity to determine how to adapt the design to meet these performance criteria; and Aquaplus possessed the manufacturing and marketing expertise to undertake the necessary adaptations and minimise production costs. The previous humanitarian experience of the key leads at Aquaplus and Université Laval ensured a basic understanding of the emergency response context. Each organisation had complementary interests: Oxfam was seeking a better water treatment system; Université Laval aimed to publish research findings generated from the process; and Aquaplus, as a private sector organisation, was interested in developing and marketing humanitarian products.

The project aimed to develop a solution for producing large quantities of safe water in emergency settings. This required the design and testing of different prototypes. Researchers working with Aquaplus (India) in Pune tested prototypes to verify the performance of different design configurations. Problems which could not be fully verified in India were referred back to testing facilities at Université Laval in Quebec City, where further lab testing took place using a much smaller model of the inclined plate filter.

The development of the CLARKE was partially based on experience acquired during the testing and deployment of Oxfam’s Field Upflow Clarifier Kit. This kit, developed collaboratively by Oxfam GB and the University of Surrey, overcomes the limitations of other technologies challenged by high turbidities whilst maintaining a high production yield. However, one shortcoming was the limited involvement of the kit’s potential operators (i.e. field staff) during its development; practitioners saw its set-up and operation as too complicated, and it was not widely adopted despite being considered one of the most cost efficient emergency systems available. Further involvement of potential end-users in its development could have helped simplify the system and increase uptake in the field.

Support for the proof-of-concept of the treatment process underpinning the CLARKE (i.e. inclined plate settling) was first obtained through seed funding from Oxfam in 2011. The promising results from early work in Pune in partnership with Aquaplus Ltd. led to a larger grant from the Humanitarian Innovation Fund in 2012. This work was aimed at optimising the original design and determining how it could be transformed into a collapsible system. The development of the water treatment system aimed to meet the following design criteria:

  • Maximal ‘throughput’: attaining a relatively high flow rate, as the system is intended to produce large volumes of treated water.
  • Sufficient quality: attaining the minimum quality levels set by Sphere.
  • Transportability: reducing transport costs by creating a highly mobile product.
  • Usability: ensuring the system could be operated by newly trained field staff.
  • Cost-efficiency: maintaining a competitive cost relative to production yield.

During its development, there was significant rethinking around how to best meet the criterion of transportability. This exemplified the dynamic nature of innovation and the unexpected outcomes that can arise in an innovation process. The original aim had been to emphasise the transportability criterion by designing a system with a collapsible structure. However, parallel independent work on a similar system being developed by ACH Spain indicated that a collapsible design could reduce water treatment efficiency, and the rigid structure was retained so as not to compromise water quality. This also ensured physical robustness, which was not initially considered as a design criterion. The first versions were made of mild steel that allowed for ease of manufacture and flexibility, but resulted in a very heavy system. Once the final design configuration was decided following testing in India and Canada, a lighter final product was manufactured using fibreglass.


In 2013 there was an opportunity to deploy the second prototype version in the Typhoon Haiyan response in the Philippines. However, as the prototype was made of mild steel it was decided it was too heavy to be quickly and easily deployed. By the time the final and lighter version of the CLARKE was manufactured in 2015 no humanitarian crises warranted its use by Oxfam. In view of this, it was decided to deploy the CLARKE to South Sudan instead. At the time of writing, the CLARKE is being shipped to Juba, where it will help bolster safe water supplies as part of a larger Oxfam cholera mitigation and response programme. This operation will be done in collaboration with the local government body in charge of water infrastructure and will support local capacity for treatment and delivery. This deployment will also serve as part of the ‘bottom-up’ diffusion strategy adopted for the CLARKE, including demonstrating the technology to other agencies in the field to generate interest and uptake. During this deployment the performance of the CLARKE will be carefully documented. In addition to disseminating this experience through peer-reviewed publications and conference presentations, this innovation will be further diffused at a grassroots level through RedR-India training, as has been done in the past with other water treatment equipment.

Final thoughts

The more technical aspects of this project have been presented in several international conferences and can be made available by contacting the author (caetano.dorea@gci.ulaval.ca). In addition, ALNAP has recently published a series of detailed case studies on successful innovations including the CLARKE.+A. Obrecht, Improving Water Quality and Quantity in Emergencies: The Inclined Plate Settler Water Treatment System, HIF/ALNAP Case Study (London: ODI/ALNAP, 2015). It is believed that the success of the development of the CLARKE was due to the good fit between the partners. One key contributing factor to this healthy relationship was good communication between partners with regard to roles, responsibilities, limitations and expectations. However, it is still early days for the CLARKE. The experience in South Sudan and uptake by other agencies will be critical for the wider adoption of this innovation.

Caetano C. Dorea is an Assistant Professor at the Université Laval, where he runs the Water, Sanitation & Health Research Group.