Drain Slope: 1/4 or 3/8 In/ft? Real Answers (plumbing101.i234.me) Question I read many opinions on the drain slope for nearly level runs. Some cap the slope at 1/2 inch per foot. Others allow 3 inches. Many say 1/4 inch per foot is ideal for most cases. I even considered field tests with sagged pipes and… Continue reading Drain Slope: 1/4 or 3/8 In/ft? Real Answers