Pour at least one pint directly into drain. Allow to stand 30 minutes or more. Repeat if necessary in one hour. Extremely heavy grease or root stoppages may require standing overnight. Drain may need plumbing after half hour to remove air pockets. Large basement drains may need 3 or 4 quarts for clearance. After following above directions, flush drain with hot water. Depending upon usage, drains can be kept running freely by use of this product twice a month.