PROJECT OVERVIEW

1
Ceramic Water Filters in Cambodia a Sustainable
Solution for Rural Drinking Water Treatment Joe
Brown and Mark D. Sobsey University of
Alabama and University of North Carolina School
of Public Health Category Small Projects
PROJECT OVERVIEW
KEY FEATURES
RESULTS
RESULTS
Locally produced ceramic water filters are now
used by an estimated 100,000 Cambodian households
for the treatment of drinking water. Three
NGO-managed factories produce and distribute
approximately 8,000 filters each month. These
NGOs, the Cambodian Ministry of Rural
Development, the World Bank Water and Sanitation
Programme, and UNICEF collectively sponsored an
independent assessment program of the filters
currently in use to determine whether filters
could be a sustainable solution for drinking
water treatment in rural areas. Key research
objectives identified by stakeholders were to
(i), evaluate the extent that filters improve
microbiological quality of drinking water at the
point of use (ii), evaluate the extent to which
filters protect users from diarrheal disease
(iii), determine whether and how filter
effectiveness against microbes and/or diarrheal
disease changes over time (iv), determine how
long filters are in use in households and (v),
identify factors associated with long-term use
and factors associated with discontinuation of
use to inform future and current implementation
efforts. This project has resulted in a
critical, timely assessment that has been
extremely valuable to stakeholders considering
further investment in the technology. Findings
include evidence of substantial health impacts
through use of the filters (46 reduction in
diarrheal disease in users versus non-users), a
detailed analysis of economic and social factors
that have contributed to success in some
interventions and failures in others,
identification of key challenges to scaling up
the technology at the country level, and reliable
estimates of field performance in reducing
microbiological contaminants. This holistic
approach is now being considered as the model for
how best to assess point-of-use water treatment
interventions worldwide.
Comprehensive study of long-term filter use and
factors related to successful use

• Key findings were
• Filters maintained effectiveness after up to
  nearly four years in use, both in terms of
  microbiological performance and impacts on user
  health.
• Filters were susceptible to breakage, which was
  the primary cause of discontinued use. Maternal
  education, household investment in the
  technology, and other key factors were determined
  to be associated with effective long-term use of
  ceramic filters. NGOs conducting interventions
  now have evidence that selling the filters
  results in longer duration of filter use, and
  that education and both technical and moral
  support provided to user households can
  contribute to long-term effectiveness.

• The filters were associated with an estimated
  mean 46 reduction in diarrhea in filter users
  versus non users (LPR 0.54, 95 CI 0.41-0.71
  0.52, 95 CI 0.32-0.86 in under 5s), powerful
  evidence that the filters are having a
  significant impact on public health.

Water quality impacts E. coli, turbidity
Prospective cohort study to determine overall
health impact
METHODS
To meet our objectives, this study was carried
out in three parts (i), a cross-sectional study
of the 2000 households that originally received
filters to determine uptake and sustained
long-term use, as well as factors associated with
continued use or disuse of the technology (ii),
a water quality assessment in 80 households
successfully using the filters (from part i) to
determine the microbiological effectiveness of
the filters in treating household water, focusing
on both treated and untreated water and (iii), a
longitudinal health study comparing diarrheal
disease prevalence in 80 households using the
filters successfully to 80 control households
(without filters).
Users and matched controls were interviewed to
determine longitudinal prevalence of diarrheal
diseases and other health outcomes.

• Access to new and replacement parts and filters
  was limited in the study areas, because supply
  chains were not well developed. We found
  evidence for strong and growing demand for the
  filters critical information for scaling up
  coverage.

• Filters were susceptible to re-contamination
  under field use conditions, probably because
  users were "cleaning" filters and their
  associated water storage vessels with soiled
  rags. This had not been observed before NGOs
  implementing the filters now incorporate training
  in hygienic filter cleaning to specifically
  address this issue.

BACKGROUND
An emerging household-scale water treatment
technology is the ceramic water purifier (CWP), a
household-scale, porous ceramic filter adapted
locally from the Potters for Peace model
developed in Central America. This study included
filters produced by International Development
Enterprises (IDE) from 2002 and Resource
Development International (RDI) from 2003.
Filters are produced by molding clay mixed with
ground rice husks, firing in a masonry kiln, and
treatment with a silver-based microbiocidal
solution to protect against recontamination in
use. For more information on similar ceramic
filters around the world, visit
www.pottersforpeace.org.
This trial spanned three provinces and thirteen
rural villages in Cambodia.
User support and training is critical to
long-term use and effectiveness of the technology.

• The filters reduced E. coli by a mean 98 under
  long-term, daily household use conditions. This
  was lower than expected, because laboratory
  results had indicated 99 - 99.99 reduction in
  bacterial pathogens. We now know that user
  behavior and filter care practices can adversely
  impact filter effectiveness, and that these
  factors are critical to the maintenance of a high
  level of performance in reducing microbes.
• Microbiological effectiveness of the filters was
  not observed to be closely related to time in
  use, indicating that filters maintain their
  effectiveness over long periods of time. Based
  on this finding, NGO recommendations that users
  replace the ceramic filter elements every one or
  two years (as was standard practice) may not be
  necessary.

Access to filters and filter unit parts is
difficult for rural users, who may live in remote
areas with seasonally impassable roads.
Interviews with 506 households yielded a robust
data set for analysis.
Factors associated with uptake and long-term use
of the filters in Cambodia.
The filters included in this project were
distributed by NGOs with varying levels of cost
recovery using a number of different
implementation models both with and without user
support, education, and training. CWP production
in Cambodia is now evolving from a subsidized,
NGO-based endeavor to market-based, full cost
recovery schemes that are intended to boost
sustainability and coverage. The filters now
retail for US7.50-9.50 per system (and US2.50
- 4.00 for replacement filters). Cost estimates
per liter of treated water range from US0.00025
to US0.001. Some filters are still distributed
at subsidized prices to the poorest households.

ACKNOWLEDGEMENTS
Control households in the prospective cohort
study received new filters as part of their
participation in the study. User support and
training is essential for uptake and long-term,
consistent use of the technology. NGOs in
Cambodia are incorporating lessons learned from
this study in scaling up access to ceramic
filters across Cambodia.
We thank Uon Virak, Choun Bunnara, Lim Kimly,
Michelle Molina, Oum Sopharo, Song Kimsrong, and
Van Sokheng for conducting interviews and
analyzing water samples. Special thanks to
project manager Sorya Proum. Thanks also to
Jan-Willem Rosenboom of the Water and Sanitation
Programme, the Cambodian Ministry of Rural
Development, and Douglas Wait and the UNC
Environmental Microbiology and Health group. This
project was commissioned by UNICEF and WSP-World
Bank. The views expressed in this poster are the
views of the authors and do not necessarily
reflect the views or policies of the United
Nations Children's Fund or the Water and
Sanitation Programme.
Microbiological testing of pre- and
post-treatment water yielded key data on
long-term filter effectiveness under field use
conditions.
Filter being cleaned unsafe practices while
cleaning can lead to reduced effectiveness.