Directions Open carefully. Avoid splashing. Pour slowly into drain opening. If splashed, clean up immediately. For clogged drains, use 16 oz. and allow to work for 1 hour. Flush with warm water. For slow drains, use 8 oz. twice at 15 minute intervals. Flush with warm water. For preventing future clogs, use 8 oz. weekly; allow to stand 30 minutes and flush with warm water.