THIS SUPPLEMENT INCLUDES A COMPUTER PROGRAM FOR THE "PREDICTION METHODOLOGY FOR SUITABLE WATER AND WASTEWATER PROCESSES" WHICH IS A MODEL FOR THE SELECTION OF THE MOST APPROPRIATE WATER AND WASTEWATER TREATMENT METHODS FOR DEVELOPING COUNTRIES. THE DETAILED DESCRIPTION OF THE MODEL COMPONENTS IS PRESENTED IN THE MODEL PUBLICATION. THE COMPUTER VERSION ALLOWS A SIMULATION OF THE FUTURE AT FIVE YEAR INTERVALS FOR 20 YEARS.