In a conventional system, the wastewater exits the home and enters one or more septic tanks. The inlet and outlet of these tanks are located near the top so to allow solids in the wastewater to settle to the bottom. This is the septic tanks primary function, to keep the solids from leaving the tank. These solids are later partially broken down by anaerobic bacteria. Remaining solids are removed by having the tanks pumped. Pumping should be done every two years.

After the effluent leaves the tanks, it is gravity discharged to a "leech" field or series of trenches. A trench system has the best performance characteristics, but requires a much larger area. The "leech" bed is most common. In both systems the effluent passes through the native soil on its way to the ground water. This is why there must be 36" inches of soil between the bottom of the discharge pipe in the bed or trench, and any ground water or bedrock present. After the water passes through this layer of soil it has been purified enough that it may be added back to ground water without posing a health hazzard.

Most of these beds are constructed in the field utilizing clean stone and perforated PVC pipe. There are also performed plastic chamber on the market such as Infiltrator. These chambers offer unique performance characteristics that enhance installation and overall systems performance.

This type of system is the most inexpensive discharge system available. However many areas do not have the native soils present to allow this type of system. Talk to your installer or soil tester about what would be best for your lot. If you are currently looking at a piece of property, you should know what type of system you will be able to install.

Specific dimensions and cited requirements refer to Wisconsin Administrative Code ILHR83. This is not to imply that this website has been reviewed, approved, or recognized by any regulatory agency.