Some useful links for reference materials and advice:

Water and Sanitation

International water and sanitation research, The Netherlands

Department of water engineering in developing countries, Loughborough
University, UK

Library and technical support in environment, water and sanitation, DFID, UK

CLTS official website, IDS, UK

Trendy global discussion forum for water, sanitation and hygiene enthusiasts

Dew Point

Water, Engineering and Development Centre (WEDC), Loughborough University