Household water treatment systems
Practical Action
to be ground into a particle size of 0.2 to 2mm and heated again to above 150ºC; this will
increase the pore size needed for effective adsorption.
Multi-Stage Filtration
Filtration Stages
Terminal
Disinfection
Dynamic
Gravel Filter
Coarse
Gravel Filter
Slow Sand
Filter
Safety
Barrier
Raw
water
source
Figure 6: Layout for a multi-stage filtration system (Illustration by A. Elias based on Galvis, G.
IRC 2006)
This system combines some of the less complex processes of water treatment: coarse gravel
filtration and slow sand filtration. Removing large particulates through sedimentation or sand
traps should still be carried out before running water through a multi-filtration system. It is most
suited to rural communities and small to medium sized towns where the use of chemical
treatment or more complex technologies would not be feasible.
The International Water and Sanitation Centre has published some guidelines on how to build
such a system, including the design process, which can be downloaded at:
http://www.irc.nl/page/31601
References and further information
Caincross, S., Feachem, R. (1993) Environmental Health Engineering in the Tropics: An
Introductory Text, 2nd Edition. West Sussex, John Wiley.
McConnachie, G.L., Warhurst, A.M., Pollard, S.J.T. and Chipofya, V.H. (1996) Activated carbon
from Moringa husks, 22nd WEDC conf., "Reaching the unreached - challenges for the 21st
Century", New Delhi, India, WEDC
Pickford, J. (1977) Water Treatment in Developing Countries, in Water, Wastes and Health in
Hot Climates. London, John Wiley, London.
Sanchez, L. D., Sanchez, A., Galvis, G., Latore, J. (2006) Multi-Stage Filtration. IRC
International Water and Sanitation Centre [online]
WHO (2003) Asbestos in Drinking-water: Background Document for Development of WHO
Guidelines for Drinking-water Quality. Geneva, World Health Organisation. [online] Available at:
WHO (2004) Fluoride in Drinking-water. Geneva, World Health Organisation. [online] Available
at:
10