The TerraClear Ceramic Water Purifier (CWP) is a zero-emissions, point-of-use ceramic water purification system. The product consists of a pot-shaped ceramic filter element set in a plastic receptacle tank with a lid and spigot to protect filtered water from recontamination.
Ceramic filtration is the use of porous ceramic (fired clay) to filter microbes or other contaminants from drinking water. Raw water seeps through the ceramic filter element by gravity at a post-production rate of 1.7 to 3.5 liters per hour producing potable water.
The CWP can filter up to 55 liters per day and store up to 36 liters of safe water in the receptacle tank. Maintenance consists of scrubbing the ceramic filter element to unclog pores and washing the receptacle tank to prevent bacterial growth. The product is a low technology solution to households’ lack of access to safe water: the filter is fed by gravity and the replaceable spigot is the only moving part.
The filters themselves are kiln-fired clay impregnated with colloidal silver. TerraClear manufactures the filter elements at a purpose-built factory near Pakse, Lao PDR. Locally sourced clay and rice husks are ground to a specific size and mixed at precise levels. This precise ceramic mixture of clay and rice husks is then molded into pots and fired in a kiln. During the firing process, the rice husk burns and creates the extremely small pores which, due to size exclusion, act as physical barriers to micro-organisms, making the filter effective at removing bacteria, protozoa, helminths, turbidity and other suspended solids. After firing, the filters are brushed with colloidal silver, infusing the clay pores to provide a permanent, secondary defense, which when used correctly removes over 99% of bacteria 1 2 3 4 .
The ceramic filter element has a potential useful life of 7 years or longer 5. Lifespan mainly depends on the quality of the input water and the care taken to avoid breakage.
The water treated by a CWP has no significant taste issues. CWPs have functional stability, meaning they only have one moving part (the spigot) and require no external energy source (such as a UV lamp) or consumables (such as chlorine packets, or media that must be regenerated or replaced).
Several ministries of the Government of Lao PDR have certified the TerraClear CWP. Testing and certification was provided by the Ministry of Food and Drug, providing a “Pass” for the following tested parameters: Hardness, pH, Total Coliforms, E. Coli, and Fecal Coliforms 6. The Ministry of Health has also endorsed the product following a study of the filters in 2012, which tested for E. Coli and Total Coliforms from a number of water sources, including: Shallow well, Spring water/Mountain source, River water, Borehole, Town water, Pond water, and River water. The certificate from the Ministry of Health states that “the water filter is appropriate for every water situation throughout the country” 7.
TerraClear filters are regularly sold with refillable 12-liter bottles which can be used to collect untreated water and positioned on the system to automatically flow into the filter. In addition, stands are also produced and regularly purchased by end users for convenience and hygiene. A pictorial instruction sticker is fixed to the side of each CWP unit, along with contact details to facilitate questions and replacements.
1 Roberts M (2003) Ceramic Water Purifier – Cambodia Field Tests, IDE Cambodia, Phnom Penh, p 4-6
2 Brown J, Sobsey M, and Proum S (2007) Improving Household Drinking Water Quality: Use of Ceramic Water Filters in Cambodia, WSP Field Note, World Bank Water and Sanitation Program, Phnom Penh, p 22-32
3 Bloem SC (2008) Silver Impregnated Ceramic Water Filter – Flowrate versus the removal efficiency of pathogens, Delft University of Technology, Faculty of Applied Sciences, Delft, Netherlands
4 Phimmason, B, PhD (2011) Experiment Using Water Filter Ceramic to Decrease Coliform Bacteria in Water, Ministry of Health, National Centre for Environmental Health and Water Supply, Vientiane, Lao PDR
5 Lantagne, D (2001) Investigation of the Potters for Peace Colloidal Silver Impregnated Ceramic Filter – Report 1: Intrinsic Effectiveness, p 58 [Online] Available from: http://web.mit.edu/watsan/Docs/Other%20Documents/ceramicpot/PFP-Report1-Daniele%20Lantagne,%2012-01.pdf
6 Government of Lao PDR (2011) Certificate of Testing for TerraClear CWP, Ministry of Health, Drug and Food Testing Centre, Vientiane, Lao PDR.
7 Government of Lao PDR (2012) Certificate of Testing for TerraClear CWP, Ministry of Health, National Centre for Environmental Health and Water Supply, Vientiane, Lao PDR.
