Over 1 billion people worldwide lack access to improved drinking water sources, and many more lack access to safe water as defined by the World Health Organisation. Conventional piped water systems using effective treatment to deliver safe water to households may be decades away in much of the developing world, meaning that many of the poorest people must collect water outside the home. Unsafe drinking water contributes to a staggering burden of water-related disease in developing countries, borne primarily by the poor. The Millennium Development Goals aim to halve the proportion of people without access to safe water by 2015.
Many of the Cambodian population lack access to improved drinking water sources and diarrhoeal diseases are the most prevalent cause of death in children under 5 years of age. The authors discuss low-cost options for the treatment of drinking water at the household level which are being explored by the Cambodian government and non-governmental organisations (NGOs) working in Cambodia. An estimated 100,000 + households in the country now use CWPs for drinking water treatment.
Two candidate filters were tested for the reduction of bacterial and viral surrogates for waterborne pathogens using representative Cambodian drinking water sources (rainwater and surface water) spiked with Escherichia coli and bacteriophage MS2. Results indicate that filters were capable of reducing key microbes in the laboratory with mean reductions of E. coli of approximately 99% and mean reduction of bacteriophages of 90-99% over 600 litres throughput.
However, more work is needed to further characterise the chemical composition and effectiveness of the various silver-based preparations used in ceramic filter manufacture in developing countries. No standard exists and few data are available. In addition, low-cost ceramic filtration for drinking water treatment in developing countries comprises a diverse range of technologies which vary by overall design, production method, clay and other materials, quality assurance and quality control (QA/QC) procedures, burnout material, firing temperatures and methods and chemical (e.g. so-called ‘colloidal silver') amendments. Because the design and available materials and methods vary widely from region to region, effectiveness data for one ceramic filter design may not be representative of other systems.
The authors conclude that CWP technology, although not as effective as chlorination or boiling combined with safe storage, does reduce bacteria and viruses in water and may be suitable for the treatment of moderately contaminated drinking water sources. However, more work is needed to increase the evidence base of effectiveness for these promising interventions, including long-term health impact studies and field testing of filters under daily household use conditions in developing country settings.