For an overview of activities at different levels of care, see our manual folder Principles and Practice of PHC (Section 6. Look also at 5.3, Diarrhoea; 5.6, Common Local Diseases related to water; 5.8. Infections prevented by better water & sanitation).
Look through WHO's publications on water, sanitation and health
WHO offer a Safe health-care waste management policy paper (2pp pdf)
IRC, the International Water and Sanitation Centre, has many useful resources and tools