Photo: Martin Septic If your home has an onsite wastewater management system or septic system, it means there is a leach field attached to that septic system. Leach lines (also known as leach field, percolation bed, leach bed, or filter bed) occupy the final phase of your home’s sewage treatment system. What are leach lines, what do they do, what can go wrong with them, and how do you know when it is time to replace your leach lines? To understand leach lines, you first need to understand how septic systems work. HOW SEPTIC SYSTEMS WORK Septic systems or onsite wastewater management systems do the same thing as municipal waste systems. The difference is the septic system is situated in your home and serves the needs of your house, says Mike Dunfee Property Management , unlike the public waste system which serves the entire city. The purpose of the septic system is to capture wastewater from your home and render it harmless by killing the pathogens in it. That water i...