As a homeowner, if you’re not on municipal water and sewer services, you are responsible for maintaining your septic system. Proper design, construction, and maintenance of a septic system are essential for the health of your system and your family.
Big Sky Watershed Corps member, Jillian Henrichon, explains the basics of proper septic maintenance and their importance to keeping our waters clean.

The EPA lists four things you can do protect your septic system:
- Inspect your system every year and pump the tank every 3-5 years, or as necessary
- Use water efficiently
- Don’t dispose of household wastes in sinks or toilets
- Care for your drain field
Septic systems in Montana must meet state, city, and county regulations. Some regulations include having a drain field at least 100 feet away from the nearest 100-year floodplain and the bottom of the drain field 4 feet above the 100-year flood elevation. Get in touch with your county health/sanitation department to learn about requirements and permits that you will need to install a new septic system.
Maintain your Septic System
Septic systems are designed to hold, treat, and dispose of household wastewater. Household wastewater contains bacteria, viruses, household chemicals, and nutrients, all of which can cause health problems and pollute groundwater or surface water. Therefore, treatment is needed to prevent water contamination.
Pumping and inspecting your septic system every couple years can help your system run longer, save money, and protect water quality. Ageing septic systems are a huge threat to future water quality.
Throw a pumping party! Many companies offer discounts if pumping multiple residences in a neighborhood.
How Your Septic System Works
Most septic systems have two major parts, a septic tank and a drain field. Wastewater from sinks, toilets, showers and other drains flows to an underground septic tank. In the tank, solids settle to the bottom and a layer of scum or grease floats to the surface on an intermediate liquid layer. As raw sewage is added to the tank, an equal amount of liquid flows out into the drain field.
The drain field is where most treatment occurs. It consists of gravel-filled trenches containing plastic chambers or perforated plastic pipe. Effluent moves through the pipes and seeps into the surrounding soil. Soil particles filter out small suspended solids and organic matter, while soil bacteria break down harmful microorganisms and other organic components. Viruses adhere to clay particles in the soil and eventually die. The treated effluent continues its downward flow through the soil layers.
Maintain Your System to Keep it Functioning Properly
Regular maintenance will keep your system functioning properly and extend its life.
Do not use additives in your system. They provide no benefit and may harm the system. Additives can result in sludge being flushed into the drain field, plugging the soil pores.
Pump the tank regularly. Depending on your water use, pump the tank every two to five years.
Discharge all wastewater from the septic tank. Don’t run wastewater from laundry or a sauna directly into the drain field as the detergent scum will quickly clog soil pores and cause failure.
Avoid compacting soil over the drain field. Compacted soil cannot treat wastewater and once compacted, it can’t be restored.
Best Management Practices to Keep Your System Working
Conserve water. Excessive water use is the most common cause of septic failure, so reduce water used for bathing, laundry, and flushing the toilet.
Repair water leaks. Repair leaking pipes, sticking float valves in toilets, and dripping faucets to reduce wastewater. A dripping faucet can waste 15-20 gallons per day.
Take shorter showers and choose showers over baths. A full bath uses 50-60 gallons of water, while a shower uses only about 5 gallons per minute.
Install low-volume toilets and low-flow shower heads. Typical toilets use 5-6 gallons per flush, providing nearly half of the wastewater from a house. Toilets using only 1.5 gallons of water are available.
Do not use the toilet as a waste basket. Don’t flush facial tissue, diapers, tampons or any kind of plastic down the drain.
Do not use garbage disposals. Ground up garbage does not decompose easily, causes rapid build-up of solids in the tank, and may move solids into the drain field, clogging pipes and soil pores.
Never put coffee grounds down the drain.
Dispose of household hazardous waste properly – not down the drain. Contact your county sanitarian to learn about proper hazardous waste disposal.
Do not flush or pour unused, unwanted or expired medications down the drain. Medications are being found in groundwater and the consequences for human and environmental health are not fully understood. Take your medications to a “take-back” collection event. If that is not possible, add water and then ashes, dirt, kitty litter or coffee grounds and place in an outer container, such as a plastic tub (to prevent discovery) and dispose with household trash.
Wash only full loads in the dishwasher.
Wash only full loads of laundry. To avoid overloading your system, spread washing out over the week instead of washing several loads in one day. A single load takes about 40 gallons of water.
Minimize use of household chemicals and cleaners. Normal amounts of detergents, bleach, drain cleaners and other cleaners won’t harm bacterial action in the system.
Signs of a Problem With Your System
Sewage backup in your drains or toilets. This may be black liquid with a bad odor.
Slow toilet flushing.
Wet areas or water seeping near the drain field. it may or may not have an odor.
Excessive growth of aquatic weeds or algae in the lake near your home. Incomplete treatment of nutrient-rich wastewater seeping from your system promotes this growth.
Bacteria or nitrates found in your well water. This indicates a serious contamination problem that may come from your own or a neighbor’s failing system.
What to Do if Your System Fails
Have your tank pumped. This may solve the problem. If the drain field or household piping is clogged or if high water levels are a problem, this won’t help.
Fence off the area to minimize human, pet or wildlife contact with wastewater.
Don’t use additives – they may harm your system.
You may need to upgrade or replace the system or drain field. A permit from the county health department is required for all new construction and replacement.
Guides and Resources:
State of Montana Subsurface Wastewater Standards
EPA Homeowner’s Guide to Septic Systems
EPA Homeowner’s Septic System Checklist
For more information about your local area’s Septic System requirements, contact your local Health Department.