Cheap water and sanitation technologies that provide a level of service equivalent to conventional systems are becoming available. Technicians working in small towns, however, may be unfamiliar with them or unwilling to change. In some small towns in Latin America relevant technologies with low investment and maintenance costs are being successfully piloted.

A paper from the World Bank’s Water and Sanitation Program highlights lessons learned during a symposium on alternative technologies for water and sanitation supply in small towns held in Lima, Peru. It summarises technical data on costs and requirements for their operation and maintenance.

One new technology, successfully trialled in the Bolivian capital La Paz, is condominial water distribution. Water and sewerage lines are extended along pavements and inside people’s compounds rather than having to dig up streets. A connection point is created for each group of houses, rather than to each house. Meters are installed at each condominium connecting point. Construction and maintenance costs are reduced through active community participation. Maintenance can be carried out without disturbing large numbers of users.

Another technology relevant for small towns is the settled or small-diameter sewerage system. This is commonly used in the United States and Australia and has recently been adopted in Colombia. Domestic waste water is initially settled in a septic tank that intercepts solids before being conveyed into the municipal sewerage system. In order to achieve potential cost savings authorities must take responsibility for ensuring that septic tanks are desludged, as it is unlikely that householders will do this themselves.

Multiple-stage filtration consists of combining thick gravel filtration with slow sand filters. This technology has produced good results in Colombia where there are approximately 50 operating plants. It is cost effective, particularly in small systems where the cost of land is low and local labour and materials are available.

Ecological sanitation, using latrines that separate excreta from urine, has the advantages of recycling faeces for agricultural use, preserving water and preventing contamination of soil and groundwater. However, initial investment costs are higher than dry or pour-flush latrines. After each use ashes, dried sand or vegetal material must be supplied so it is essential to ensure householders understand the system and its maintenance requirements.

In small towns it is important to find systems with:

• little or no energy consumption and minimal use of chemical products and mechanised equipment
• efficient operational and maintenance procedures
• stable operation, regardless of fluctuations in flow and quantities of organic material – a common occurrence with waste water in small towns
• the ability to deal with sludge.

The author notes that:

• Consideration must be given to how families manage water, dispose of excrement and clean themselves after defecation.
• Regardless of how complex systems may be, it is necessary to implement regular follow-up and access technical assistance.
• Small town planners must be shown a range of options and made aware that there is more than one useful alternative.
• Information and best practice can be disseminated by creating regional centres for technology development and promotion.

Source(s):
‘Alternative technologies for water and sanitation supply in small towns’, World Bank, Water and Sanitation Program, by Alfonso Alvéstegui, Field Note, April 2005 Full document.
‘Tecnologías alternativas para la provision de servicios de agua y saneamiento en pequeñas localidades’, World Bank, Water and Sanitation Program, by Alfonso Alvéstegui, December 2004 Full document.

Funded by: Swiss Agency for Development and Cooperation, Panamerican Health Organization (PAHO)

id21 Research Highlight: 11 April 2006

Further Information:
Water and Sanitation Program
Latin America and the Caribbean Region
World Bank Office, Lima
Alvarez Calderon 185
San Isidro
Lima 27
Peru

Tel: +511 6150685
Fax: +511 6150689
Contact the contributor: wspandean@worldbank.org

Water and Sanitation Program - Latin America and the Caribbean Region

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