Your septic tank isn't the only part of your home's septic system that could cause problems. A failing drainfield can also put your septic system at risk of an expensive and time-consuming rebuild. Learn how septic system drainfields can fail over time and what you can do when these failures occur.

How Drainfields Work

Drainfields play an essential role in your home's septic tank system. After the solid waste and liquid effluent is separated within the septic tank, the effluent travels into the drainfield through a series of perforated pipes buried in gravel-lined trenches. In the drainfield, the liquid effluent is slowly absorbed, filtered and eventually returned into the water table.

Common Causes of Drainfield Failure

There are several issues that could eventually lead to drainfield failure:

  • Infrequent septic tank pumping - Not pumping your septic tank according to the recommended schedule for your household and septic tank size can cause solids and grease to migrate into and eventually clog the drainfield.
  • Activity over the drainfield area - Any sort of activity performed over the drainfield area, whether it's driving vehicles and/or equipment over the drainfield, building pools and other structures or covering the area with pavement, concrete or artificial turf, can potentially damage the drainfield.
  • Broken septic tank baffles - Septic tank baffles can break off and migrate into the drainfield.
  • Poor groundwater runoff control - Poorly controlled groundwater runoff can saturate drainfields, causing them to clog.
  • Poor drainfield construction - Drainfields that are constructed with improper slope, poor pipe layout, improper gravel placement or over areas unsuitable for construction (such as a stream bed) can fail early on.
  • Root intrusion - Root intrusion from nearby trees and shrubs can puncture pipes and cause drainfield failures.
  • Use of drainfield and septic tank additives - Many treatments that claim to extend the life of the drainfield or septic tank can actually do more harm than good.
  • Overextensive growth of the drainfield biomat - The septic biomat can become thick enough to clog the soil, preventing liquid effluent from filtering into the soil.

Drainfields can also succumb to old age. According to Inspectapedia, the average lifespan of a typical septic system drainfield ranges from 10 to 20 years when properly cared for.

Symptoms to Look For

Most drainfield failures occur along a long period of time and there are plenty of symptoms that often signal impending drainfield failure:

  • Greener grass over the drainfield site - An overly green patch of lawn over where your drainfield sits is often a first sign that something's amiss with the drainfield. Excess biomat buildup and anaerobic conditions can create an overly nutrient-rich environment for grass to grow.
  • Perpetual dampness - A clogged drainfield can cause the ground above it to be constantly damp and soggy, since gray water that would normally percolate downwards instead travels up towards the surface.
  • Bad odors - Drainfield problems can also cause noxious odors to rise from the drainfield and other portions of the septic tank system.
  • Slow or sluggish drainage - Drainfield problems can cause toilets to flush sluggishly and drains to empty slowly. Sewage backups can also occur if the problem isn't treated in the long run.

Repair or Replace?

In most cases, the best way to deal with a drainfield failure is to simply build another drainfield in a pristine location. Over time, the old drainfield site will dry out and eventually recover, allowing it to be used when the new drainfield has reached its life expectancy. It's always a good idea to have your contractor carefully plan the construction of a new drainfield so that it offers the longest possible working lifespan.

In the meantime, there are plenty of things you can do to extend the life of your drainfield. For instance, pumping your septic tank on a regular basis can prevent solids and grease from migrating into and clogging the drainfield. You should also refrain from using additives and treatments that could also harm the drainfield.

Contact a local professional, such as Rob's Septic Tanks Inc, for more information.