The objective of this study was to evaluate the effect of different types of backwashing and start-up strategies on the quality of filtered water, specifically during filter ripening. The start-up strategies consisted mainly of delay after backwash, filter to waste before start-up and slow start, and various combinations of these. The experiments took place in the Pont-Viau drinking water plant in Quebec, Canada, which has a total capacity of 120,000 m3/d. They were performed on four filters, labeled F10 to F13, which are dual-media (sand-anthracite) rapid gravity filters designed to operate at a filtration rate of between 4 m/h and 11 m/h. Normal backwash conditions consisted of a 5-minute air scour followed by a 9-minute water rinse. After backwashing, a 2-minute filter to waste precedes return to service. Includes 8 references, tables, figures.