Maintenance Tips for a Septic Drain Field

Sand and Gravel Drainage System
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Underneath every drain field is a network of buried pipes.

One of the charms of living in a rural setting is that your home is likely to be serviced by a septic system. Your system can function for years without causing problems or even being noticeable, but if you misuse it or neglect it, it will remind you of its presence with signs your nose can detect. The odors can come from the tank, but more often, they're coming from the drain field, which is the termination of the system and its most sensitive and important component. Prevent that from happening by understanding how your system operates so you'll know what it takes to keep your drain field open and happy.

Septic Design

Sanitary System Diagram
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The tank is the belly of a septic system and the drain field the elimination system.

To properly treat waste and sewage, a septic system needs two primary components. The first is a tank to collect raw sewage and the other is a drain field. Water enters the tank from the plumbing system and basically stagnates there. Solid matter drops to the bottom of the tank, and the liquid, which remains on top, flows out to the drain field. As this effluent percolates through the soil, pathogens and impurities are removed, and at the end of the process, the purified waste water enters the water table.

Most septic systems are gravity fed. The tank is located at a lower elevation than the house, and the drain field is at a still lower elevation. When topography or building design don't allow for this type of system, a transfer pump may be located in the house or in the septic tank to keep water circulating. The presence of a pump, which can get clogged by insoluble debris, makes a septic system even more sensitive and vulnerable to blockages.

Enter scum, sludge and grease. If all a septic system has to handle is bathroom waste, the tank can digest most of it, and the water heading out to the drain field is relatively clear. However, grease, oil and kitchen waste provide an unwelcome plot twist. Grease and oil don't mix with water, and they form a scum layer that remains on the surface of the tank water and can flow out to the drain field. These impurities settle into the soil, binding the soil particles and turning the ground to clay. The drain field becomes progressively less able to process waste water, which instead of soaking in, forms odorous pools on or near the surface. At the end of this dark tale, the ground becomes saturated and the drain field must be relocated.

Septic Care Begins in the Home

Under the sink.
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Pouring grease down the drain can clog your drain field as well as your garbage disposal.

Your septic field may be several hundred feet away from your house, but it's affected by what you do in your kitchen, bathrooms and laundry room. If you think of your garbage disposal as a repository for cooking grease, you're risking clogging the arteries of this all-important part of your plumbing system. The same is true every time you flush a large, insoluble object, such as a diaper, in one of your toilets. Just like your own digestive system, a septic tank can handle only biodegradable waste. Here's a short checklist of the most important do's and don't's for maintaining the health of your drain field.

Do:

  • Remind everyone who uses your bathroom to flush only waste and toilet paper.
  • Keep a trash bucket close to the kitchen sink and use it for greasy, oily and starchy food waste.
  • Get your tank pumped regularly. Pros recommend doing it every three years or when the sludge layer—which you can measure by inserting a long pole through the access door—is more than one-third of the total depth of the tank.
  • Divert runoff from your house or other parts of your property away from the drain field. Excess water slows the percolation process and increases the chances of drain field failure.
  • Check the operation of your transfer pump frequently, if you have one.

Don't:

  • Drive on the drain field. Your car will compress the soil and could break one of the drain pipes.
  • Build on the drain field. A certain amount of evaporation keeps the drain field healthy, and any structure you place on the field, including decks, reduces the square footage that is open to the atmosphere.
  • Plant trees or bushes with 100 feet of the drain field. Roots are attracted to the drain pipes, and if they start growing inside them, you'll probably have to dig up the pipes to remove the roots. It's okay—and even desirable—to plant grass or wildflowers, because ground cover reinforces the soil and prevents erosion.
  • Pour insoluble liquids, such as paint, down the sink or flush them down the toilet. Many such liquids are lighter than water and end up clogging the drain field.

What About Septic Additives?

Vacuum Truck At Work
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Instead of introducing additives, consider pumping your tank more frequently.

A septic system works best when you put into it only what it is designed to handle, which includes human waste and degradable toilet paper. Research has shown that introducing enzymes to speed up digestion may reduce the scum layer by breaking down greases and oils, but this can actually be bad for the drain field. The scum layer holds greases and oils, and when it breaks down, these harmful contaminants are more likely to reach the leach field. Rather than flushing additives down the toilet, it's a better idea to get the tank pumped more often.

This isn't a clear-cut issue, and some homeowners choose to use additives. If you're one of them, forget the old wive's tales that recommend yeast, chicken manure or hamburger meat. The best additives are enzymes, which aid digestion by breaking up organic matter into smaller molecules that can be flushed away. Never introduce cleaners that contain sulphuric or hydrochloric acid or hydroxide compounds. These powerful chemicals can destroy pipes, and even if that doesn't happen, they'll end up contaminating the groundwater.