Summary of Week 5 of Introduction to Household Water Treatment and Safe Storage (Coursera – École Polytechnique Fédérale de Lausanne)
It is important to understand whether household water treatment (HWT) products are achieving improvements in health (i.e. removing pathogens). Users do not only need access to effective options, but use them correctly and consistently. By testing the products, governments, implementers and funders can be informed of the performance.
Efficacy: The World Health Organisations (WHO) developed global performance standards based on their drinking-water risk-based approach. WHO has a tiered evaluation – highly protective, protective and limited protection – using log removal values of viruses, bacteria and protozoa. Chemical parameters are important but have yet to be developed. It is important to note that WHO measures efficacy (i.e. removal under controlled conditions), not effectiveness (i.e. removal in the real word).
Compliance: The consistent use of HWT is highly context-dependent and can be affected by personal and external factors. Conceptual frameworks to analyse compliance include the RANAS psychological model and IBM-WASH. Compliance is hard to measure.
Health impact: How much can diarrhea be prevented by improving water quality alone? There are significant health gains but it is complicated and expensive to measure. Routine monitoring and evaluation should focus on use before attempting to measure health impact.
Cost-effectiveness: Cost-effectiveness could consider cost benefit (money for money), cost effectiveness (money for DALYs) and willingness to pay (money for HWTS). Cost benefit adds up the costs of the intervention (e.g. meeting the Water MDG target) and weights it against the benefits resulting from the intervention (e.g. reduced diarrheal disease). Cost effectiveness looks only at the cost and considers which approach is the cheapest to achieve a desired outcome. One study found that chlorine and SODIS had the lowest cost.
Often decisions on the use of HWTS technologies are made on the program or government level. Selecting options comprises establishing the context (e.g. water to be treated), defining objectives and assessing the options against objectives. The criteria used is important, and multi-criteria decision analysis can be applied to the selection process.