Operations & Maintenance Permitting

OWTS Process

See the full list of permits required for the operation and maintenance of an onsite wastewater treatment system.

The typical onsite wastewater treatment system (OWTS) consists of a septic tank and absorption bed (sometimes called the leaching field or soil treatment area - STA). The septic tank is usually made of concrete or other durable materials. Most tanks will have a capacity of 1,000 gallons or more and will be divided into two compartments. Sewage (or effluent) from the dwelling flows through a building sewer and enters the first compartment of the tank. Here, bacterial decomposition occurs and materials which cannot be digested settle to the bottom as sludge or float to the top to form a scum layer.

Higher Level Treatment Systems

The remaining liquid then flows into the second compartment of the tank through a series of baffles, where additional treatment occurs. Although most tanks are non-mechanical, some will have a motor or aerator which agitates the sewage, and are referred to as higher level treatment (HLT) systems. These mechanisms are an integral part of the tank and should not be removed or disconnected as this may seriously affect the operation of the system. See HLT Systems and Operating Permits.


From the tank, the effluent is piped to the absorption bed and enters a series of perforated pipes bedded in gravel and underlying soil before flowing naturally back into the groundwater system. The filtering action of the soil removes most of the harmful bacteria. The result is a high degree of treatment occurring in a natural, environmentally sound process.

Absorption Bed

The absorption bed is where treated wastewater enters the soil; failures are common in this component of the OWTS Since the plastic (PVC) pipes in the bed are usually one foot deep or less, they are quite susceptible to damage. Vehicles should never be driven or parked on an absorption bed. In addition, to the potential pipe damage, the soil may be compacted. This will prevent proper absorption of the sewage. Animals such as cattle or horses may also compact the soil and damage pipes. If your OWTS is in a pasture, it should be fenced to keep livestock out.

Erosion can seriously affect an OWTS by removing the soil cover and allowing sewage to escape from the bed. This can be prevented by maintaining proper drainage and establishing a good vegetative cover (excluding trees) above the bed. If the bed is located in a lawn area, watering should be restricted to prevent saturation of the ground.


Although OWTS are very effective, not all contaminants can be removed by these systems. Nitrates, a chemical by-product of human waste, are not removed and may impact the groundwater. Distance separation from wells and proper system maintenance is necessary to increase treatment effectiveness as well as the lifespan of the system.


One of the most important factors in proper OWTS operation is being careful of what goes into the system. An OWTS is designed to treat only household wastewater. Although typical household soaps and cleaners should not cause a problem when used properly, liquids such as paints, solvents, thinners, pesticides or photographic chemicals should never be poured down the drain. These materials can damage your system and seriously pollute the groundwater, and possibly your own well, too.

Likewise, items such as disposable diapers, cigarette butts, sanitary napkins and baby wipes should be kept out of the system. Kitchen waste such as potato peels, eggshells and coffee grounds do not readily decompose and should be thrown out rather than put through the garbage grinder. Grease is probably the worst enemy of your OWTS; pans should be wiped clean prior to washing and excess grease or drippings should never be poured down the drain.

Avoid Overloading System

Unlike a public sewer, your OWTS is designed to accept a certain sewage flow (about 75 gallons per person per day) with a safety factor for peak water use periods. Prolonged overloading of the system may result in sluggish drains, backups or surfacing of sewage in the absorption bed. Therefore, it is recommended that water use be spread out. For example, don't do multiple loads of laundry back to back or permit three or four showers to be taken in a row. This will allow the system to accept the flow evenly without serious overloading.

Take a look at the Septic System Maintenance Brochure (PDF) for more information.


Despite the best of care, some systems will malfunction over time. If your OWTS should back up into the dwelling or leak from the absorption bed, contact Jefferson County Public Health at 303-232-6301 immediately. We can advise you on procedures to repair the system.


In normal amounts, household chemicals should not affect the proper functioning of your OWTS. Additives that claim to improve the operation of the system will probably not cause any harm, but they are not needed to assure proper operation of the system. Beware of any claims that a chemical additive will "rejuvenate" the system or make it "as good as new." Common baking soda, however, may lessen any odors from the tank and, if necessary, may be added for this reason.