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Simple, but effective

by Ghadeer Mohammed, Maika Müller, Mirja Michalscheck, Muhammad Khalifa

In depth

The tradition of using clay filters to purify drinking water still makes sense in Yemen

The tradition of using clay filters to purify drinking water still makes sense in Yemen

In rural areas and especially during humanitarian crises, clay filters are a cheap and reliable option to purify drinking water. The Arab World should make systematic use of this appropriate technology. By Ghadeer Mohammed, Maika Müller, Mirja Michalscheck, Muhammad Khalifa and Ronza Al Marji

In many cultures, clay filters are a traditional technique to purify drinking water at the household level. The technology is simple and only requires raw materials that are readily available such as clay, sand, salts and burnables like sawdust or rice husk (box). The filters grant decentralised access to quality drinking water.

Non-governmental organisations (NGOs), such as Potters for Peace, the International Red Cross, UNICEF and Oxfam promote their use in Latin America and Asia. In Cambodia 10 % of all households use such filters (Hagan et al. 2009).

The Middle East has a history of common use of clay filters. However, many people consider this practice low-tech and inferior. The market potential for clay filters should be explored systematically.

A clay filter will cost around five dollars on average, so low-income households can afford this technology. Filters can be expected to be useful for two years.

Microbiological testing has shown that the amount of E. coli bacteria in contaminated water is reduced by 99 % after flowing through the clay filter. One filter purifies one to two litres per hour.

In order to create awareness for clay filters, so called community based organisations (CBOs) may play a central role, including local NGOs, womens’ self-help groups, schools and mosques. In order to boost acceptance among the people in general, it makes sense to convince community leaders first.

In fact, even government subsidies would be justified because the filters have a great positive health impact. The assessment of Watersant (2010:2) was: “For each dollar invested in water and sanitation, on average there is a return of eight dollars in costs averted and productivity gained.”

Yemen, Gaza, Sudan and Jordan

The filters can be produced and used in rural areas and crisis areas, for instance in Yemen, the Gaza Strip or Sudan. In these areas, a large percentage of people have no access to reliable and safe drinking ­water. This holds true for 36 % of the rural population in Sudan (WHO/UNICEF 2008), and for 60 % of the people living in the Gaza Strip (Aryani 2009).

The socio-political situation of each country is different. The Gaza Strip suffers under the Israeli’s blockade which hampers the import of technical equipment. The economy has all but collapsed. Governance is problematic and the healthcare system is struggling. No doubt, wide-spread use of clay filters would help to prevent water-borne diseases, so such use should be promoted.

The situation in Sudan is characterised by political instability and conflicts. A high number of internally displaced persons and refugees are living in camps. Access to safe drinking water is probably the single most urgent need of internally displaced persons. Again, clay filters would make a difference.

In Yemen, even before the recent political turmoil, 70 % of the people who live in rural areas with hardly any infrastructure are exposed to water-borne diseases.

Even in a country with comparatively strong government capacities, clay filters can make a healthy difference. According to WHO/UNICEF, 97 % of the Jordanian people have access to water from the public supply system. The water authorities consider this water safe. Nonetheless, contamination may occur through truck delivery, in local storage tanks or rainwater harvesting facilities. Therefore, clay filters are suitable to improve the situation, especially in rural areas.

The production of clay water filters is viable almost anywhere. We ran a small project in Jordan to test matters. Water filters were made from a mix of clay and combustible materials such as coffee or sawdust.

In the mill, the combustible material burns out and leaves pores in the clay through which the water percolates. Bacteria and suspended solids get stuck in these pores. The filtration rate depends on the pore size. To make good filters, local potters merely need a mill to refine the burnable material to achieve optimal pore sizes.