Septic and Waste Treatment

Today’s septic system technology is very good.  However, these systems must be properly installed and maintained to be effective. Property owners are individually responsible for the proper installation and maintenance of their private septic systems. Septic systems are designed to collect household waste in a tank and then filter pollutants and wastewater through leach fields. Septic systems break down and neutralize contaminants before they enter ground or surface water systems. Properly designed, installed and maintained septic systems play an important part in maintaining water quality in the Flathead Watershed. Septic systems include four components: a pipe from the house, a tank which holds and begins to treat solid wastes, a distribution system which moves liquid wastes, and a drain or leach field.

Figure 5.5: Residential septic system. Source: U.S. EPA Figure 5.6: Residential septic field. Source: U.S. EPA

The septic tank is a buried, watertight container typically made of concrete (but sometimes made of fiberglass, or polyethylene). It holds wastewater, allowing solids to settle, and oil & grease to rise to the surface. The wastewater exits the septic tank and is discharged into the drain field for further treatment by the soil. Soil is a critical part of a septic system. Naturally occurring microbes and chemical processes in soil break down and remove bacteria, viruses, and nutrients. Because soil moisture and texture influences the effectiveness of septic systems, soil type is taken into account when designing systems.

Septic systems must be designed to meet state and county regulations, and be approved by local authorities. In general, they are located at least 100 feet (30.5 m) from any surface water, well, spring, or 100-year floodplain.

Septic systems need to be inspected at least every three years, and pumped every three to five years depending on use. Inspectors look for the fullness of the tank and also check for leaks. Although many tanks last indefinitely, some develop cracks potentially contaminating groundwater and posing serious human health threats. If possible, homeowners should organize neighborhood or community pumping as pumpers will often reduce the price for large jobs. Pumped sludge and scum have to be disposed of, either by putting it to beneficial use via application on farmland or by disposal at a wastewater treatment plant.

Water Use & Disposal
There are a number of steps that can be taken to ensure that a septic system lasts and does not contaminate waterways:

Community sewer facilities add an enormous density of waste to the water system. Wastewater treatment plants in the Flathead Watershed have been upgraded over the years to meet or surpass state mandated phosphorus limits and have reduced “point source” pollution considerably.  Point sources are identifiable outlets such as municipal and public sewage, stormwater outfall, and industrial discharges. New public systems in Lakeside and Somers and the expansion of areas served by public systems such as Evergreen, Whitefish Mountain, Whitefish Lake, and Bigfork have contributed to protecting our water quality. The amount of nutrients reaching Flathead Lake has been reduced through these upgrades efforts and the banning phosphorous-containing household cleaners. All citizens and businesses have a critical role, a stake, and a responsibility in maintaining healthy water systems and in reducing water pollution.

Citizens for a Better Flathead
Lake County Environmental Health Department
Confederated Salish & Kootenai Tribes
Montana Department of Environmental Quality
Designs for septic systems, circular WQB
Flathead Basin Commission
Healthy Lakes Through Living Shores DVD
National Resources Conservation Service
Flathead Conservation District
Web Soil Survey
Flathead County Environmental Health Department
Septic Yellow Pages
Listings for professional septic pumpers, installers, inspectors, and tank manufacturers
Flathead County Health Department
U.S. Environmental Protection Agency
A Homeowner’s Guide to Septic Systems http://www.epa.gov/owm/septic/pubs/
Flathead Lakers

Whitefish Lake Institute


For more information, send email to info@flatheadwatershed.org or info@flatheadcore.org.
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