University of Maryland Extension

How can I repair my failing drainfield?

Drainfields typically fail because too much wastewater has been flushed into them, keeping them constantly saturated. When too much water sits in the drain lines constantly, a bacterial mat forms along the trench walls. This slimy mat doesn't allow water to seep through it, and therefore the trenches no longer can handle the wastewater. A properly designed septic system is designed to handle a specific amount of wastewater. This is determined by how many people are in the house. Number of people are calculated by the number of bedrooms – figuring two people per bedroom. If a household overloads a system, i.e. uses way too much water each day, the drain lines never have time to dry out.

Signs of this are drains gurgling, draining slowly, water coming up through the lower house level floor drains, and wet spots in the yard. Usually these problems are most noticeable when you use a lot of water, like on laundry day. That's why it's imperative that you space your laundry loads and conserve water! Short showers, never leaving water run down a drain while washing dishes, full wash loads only (or adjusting the water level for a small load), and never doing back to back loads of laundry will all help conserve water, and therefore the amount of wastewater going into the system.

In the septic tank, only about 50 percent of solids are broken down by bacteria, the rest accumulate in the bottom of the tank until they are pumped out. Having too many solids accumulated, and too much water entering the tank at once (like doing several loads of laundry in one morning), can cause the solids to be flushed out into the drainfield where it can clog it.

Unfortunately, there is not a quick, easy fix for a failed drainfield. Short of there simply being a clog in the system that can be routed out, the bacterial mat that is typically the problem, cannot be destroyed other than allowing the trench to completely dry out for a few months. This would require a new trench system be put in its place. So rarely is there a fix other than a new drainfield being installed.

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