How Excess Water Ruins Septic Drain Fields

How a Drain Field Is Designed to Work

A well-balanced process is necessary for a healthy drain field. The wastewater, or effluent, from the septic tank is directed to a system of pipes with holes, filled with gravel and buried underground, where it is clarified. The effluent then slowly and uniformly percolates into the surrounding soil, where natural biological systems filter and treat it before it again becomes part of the groundwater supply. It's a great system as long as water is coming in at a steady, controlled pace, but it's not engineered to handle large amounts of water or sudden gushes. If excess water is applied at once, it can fill the soil, preventing it from absorbing and treating effluent, which can lead to gradual deterioration of the drain field and subsequent damage.

The Hydraulic Overload Problem Affects the Entire System

A hydraulic overload occurs when a household consumes much more water than can be safely treated by the septic system, such as when they have many more visitors than the system was designed to serve, or when they use several appliances at the same time, or if they have a leak under the sink that's constantly pouring water into the tank. The tank fills too quickly, and partially treated or even untreated wastewater is pumped into the drain field before the separation process is done. The solids and greasy materials that should be in the tank end up in the drain field pipes, clogging the gravel and soil. A biomat, or a thick layer of organic matter, develops over time along the soil interface, and eventually, absorption is completely inhibited. Professional septic cleaning and septic pumping can help keep a biomat in place; however, if a drain field becomes severely compromised, it can be very expensive to repair or replace.