Background
After the Asian Tsunami of 2004, access to clean water
became a major issue for people living on the coast of Sri
Lanka. Being aware that one of the UN Millennium
Development Goals for 2015 is to “halve the proportion of
people without sustainable access to safe drinking water”, the
American Red Cross (AmRC) and the Sri Lanka Red Cross
Society (SLRCS) collaborated to introduce an appropriate clay
water filter (CWF) technology to Sri Lanka. This is a low cost
filter that removes diarrhoea-causing bacteria from water to
make it safe for human consumption. These filters represent
a sustainable way for Sri Lankans to get safe “point of use”
water and reduce their risk of contracting diarrhoea and water-
borne diseases.
The project drew on the expertise of Cambodia-based
International Development Enterprises (IDE) for technology
and utilises similar production and marketing approaches.
The project focuses on three objectives:
• Increasing access to sustainable sources of potable water;
• Improving hygiene practices by deepening the
understanding of the transmission of bacteria.
• Improving local capacity to manage and sustain the CWF
production and marketing.
The CWF Project was designed primarily to operate in the
southern districts of Galle, Matara, and Kalutara for the benefit
of Tsunami affected persons. Its accomplishments include the
establishment of two production facilities, contracts with local
and international component suppliers and capacity building
of a cadre of competent project managers and hygiene
promoters. By the middle of 2008, 12,000 CWFs had been
distributed free of charge for the benefit of over 60,000
persons. These recipients invested their time attending a
hygiene promotion workshop where they were made aware of
water-borne diseases and how to prevent them. They also
received hands-on training on how to assemble, use and
maintain the CWFs.
By late 2008 the project had expanded its production capacity
and had moved towards the commercialization of the CWFs
based on social marketing principles.
What is the Sri Lankan clay water filter?
During the process, the CWF removes sediment and treats
contaminated water to attain quality standards set by the
World Health Organisation (WHO). Additionally, as a result of
treating the pots with colloidal silver, a second level of
protection is provided to kill any bacteria that may have
passed through its microscopic pores.
Another important quality of the CWF is that it offers secure
storage of the treated water which is easily accessible to
household members. In Sri Lanka the receptacle is made of
food grade plastic and a high quality tap is supplied for easy
assembly. Other countries have tried terracotta and stainless
steel receptacles. However plastic is highly acceptable as it is
translucent, easily cleaned and light weight. Water quality
analyses indicate that the filter eliminates approximately
98.00 percent of harmful bacteria and parasites. At an
average of two litres per hour the CWF has the capacity to
provide over 40 litres of water per day, enough to meet the
drinking water needs of most families.
When did the clay filter originate?
Water filtration for home use with porous clay and sandstone
receptacles dates back hundreds of years in both Central
America and Asia. Below is a photograph of a 1,200 year old
porous sandstone filter on display at the Sri Lanka National
Museum.
Mr. Mahesh demonstrates the point of use CWF
The CWF is a household unit for filtering, treating and storing
potable water. It consists of a porous clay “pot” suspended in
a 20 litre plastic receptacle with a tap located close to the
bottom, through which the clean water is drawn. Its operation
is straightforward: The plastic lid is removed and the clay pot
is filled with water of uncertain quality. This gravity fed water
passes slowly through the pores in the sides and bottom of
the pot and is collected in the plastic receptacle.
Photo courtesy of the Sri Lanka National Museum
The CWF technology utilised in Sri Lanka was developed in the
early eighties in Guatemala and later commercialised by the
USA based Potters for Peace Organization (PfP), which saw it as
a good response to the clean water needs of persons affected
by Hurricane Mitchell. Over the years, several African and
Asian countries have adopted the technology and have been
marketing them with high levels of community acceptance.
PfP reports that up to 20 countries are currently producing
CWFs.
The CWF has been recognised internationally. In 2003 the
Cambodian Red Cross clay water filter project won a World
Bank Development Marketplace award. More recently, in early
2008 IDE was awarded the World Bank’s East Asia Project