General Information

Onsite Wastewater Treatment Systems (OWTS) treat 20-25% of Colorado’s domestic wastewater. These systems are no longer a temporary solution until homes can be connected to municipal sewer, and are instead a permanent component of the home.

There are many facets to the systems. From installation to operation and maintenance to inspection and repair, it is important to understand your system and make informed choices. System owners play an integral role in the proper functioning and extended lifespan of their system.

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I am a first-time septic owner, or am considering purchasing property with a septic system. What do I need to know?

I bought property and am a first-time septic owner. What do I need to know?

How Your Septic System Works The Basics A typical septic system has four main components: a pipe from the home, a septic tank, a soil treatment area, and the soil. Microbes in the soil digest or remove most contaminants from wastewater before it eventually reaches groundwater. A soil treatment area is the preferred term, since it notes that treatment occurs in this area. Historically, It has been called a drainfield or leach field. A Septic system can also be termed:

  • On-lot system
  • Onsite system
  • Individual sewage disposal system
  • Onsite sewage disposal system
  • Onsite wastewater treatment system

If properly designed, constructed and maintained, your septic system can provide long-term, effective treatment of household wastewater. If your septic system isn’t maintained, you might need to replace it, costing you thousands of dollars. A malfunctioning system can contaminate groundwater that might be a source of drinking water. And if you sell your home, your septic system must be in good working order. Higher Level Treatment Systems Because many areas don’t have soils suitable for typical septic systems, you might have or need a higher level treatment system (also known as alternative systems). You might also have or need an alternative system if there are too many typical septic systems in one area or the systems are too close to groundwater or surface waters. Higher level treatment systems use new technology to improve treatment processes and might need special care and maintenance. Some alternative systems use sand, peat, or plastic media instead of soil to promote wastewater treatment. Other systems might use wetlands, lagoons, aerators, or disinfection devices. Float switches, pumps, and other electrical or mechanical components are often used in alternative systems. Alternative systems should be inspected annually. Check with your local health department or installer for more information on operation and maintenance needs if you have or need an alternative system. The Advantages of Onsite Wastewater Treatment Systems Another alternative for septic treatment is sewer systems, which pipe waste to a centralized treatment plant, typically near a river or other body of water for disposal after treatment. Besides avoiding the high cost of sewer lines, septic systems are environmentally superior to sewers because they:

  • Provide simple, effective onsite wastewater treatment
  • Allow the groundwater to be recharged onsite, which makes more clean water available for use
  • Avoid contamination of local groundwater caused by aging sewer lines, which leak untreated effluent into the soil.
  • Avoid the environmental disaster of raw sewage discharges from treatment plants during floods or processing accidents.

The Advantages is reproduced with permission from Infiltrator Systems. View more information from the Environmental Protection Agency (PDF)

How do I maintain my system?
Click here for a Public Service Announcement from National Environmental Service Centers. It provides a great reason to maintain your system.

Dos and Don’ts (adapted from National Small Flows Clearinghouse)

Do

  • Check with the local regulatory agency or inspector/pumper if you have a garbage disposal unit to make sure that your septic system can handle this additional waste.
  • Check with your local health department before using additives. Commercial septic tank additives do not eliminate the need for periodic pumping and can be harmful to the system.
  • Use water efficiently to avoid overloading the septic system. Be sure to repair leaky faucets or toilets, and check the toilet flapper valves regularly to be sure they are not leaking. Use high-efficiency fixtures.
  • Use commercial bathroom cleaners and laundry detergents in moderation. Many people prefer to clean their toilets, sinks, showers, and tubs with a mild detergent or baking soda.
  • Check with your local regulatory agency or inspector/pumper before allowing water softener backwash to enter your septic tank.
  • Use composting or trash to dispose of kitchen waste instead of using a garbage disposal.
  • Keep records of repairs, pumpings, inspections, permits issued, and other system maintenance activities.
  • Learn the location of your septic system. Keep a sketch of it with your maintenance record for service visits.
  • Have your septic system inspected and pumped as necessary by a licensed inspector/contractor.
  • Plant only grass over and near your septic system. Roots from nearby trees or shrubs might clog and damage the soil treatment area.

Don’t

  • Your septic system is not a trash can. Don’t put dental floss, feminine hygiene products, condoms, diapers, cotton swabs, cigarette butts, coffee grounds, cat litter, paper towels, latex paint, pesticides, or other hazardous chemicals into your system.
  • Don’t use caustic drain openers for a clogged drain. Instead, use boiling water or a drain snake to open clogs.
  • Don't direct hot tub and pool drains to your septic system.
  • Don't direct water purification or softener backwash to your septic system.
  • Don't use plastic landscape sheets or irrigation over your soil treatment area.
  • Don’t drive or park vehicles on any part of your septic system. Doing so can compact the soil in your drainfield or damage the pipes, tank, or other septic system components.

Maintenance Schedule

You should have a typical septic system inspected at least every 3 years by a professional and your tank pumped as recommended by the inspector (generally every 3 to 5 years). Alternative systems with electrical float switches, pumps, or mechanical components need to be inspected more often, generally once a year. Your service provider should inspect for leaks and look at the scum and sludge layers in your septic tank. If the bottom of the scum layer is within 6 inches of the bottom of the outlet tee or the top of the sludge layer is within 12 inches of the outlet tee, your tank needs to be pumped. Remember to note the sludge and scum levels determined by your service provider in your operation and maintenance records. This information will help you decide how often pumping is necessary. (See the Dos and Don’ts above.)

Four major factors influence the frequency of pumping: the number of people in your household, the amount of wastewater generated (based on the number of people in the household and the amount of water used), the volume of solids in the wastewater (for example, using a garbage disposal increases the amount of solids), and septic tank size.

Some makers of septic tank additives claim that their products break down the sludge in septic tanks so the tanks never need to be pumped. Not everyone agrees on the effectiveness of additives. In fact, septic tanks already contain the microbes they need for effective treatment. Periodic pumping is a much better way to ensure that septic systems work properly and provide many years of service. Regardless, every septic tank requires periodic pumping.

In the service report, the pumper should note any repairs completed and whether the tank is in good condition. If the pumper recommends additional repairs he or she can’t perform, hire someone to make the repairs as soon as possible.

Learn more valuable information (PDF)

What do I need to do when I am ready to sell my home?
Check with your County Health Department

Each county has different requirements when transferring property. Check with your local county health department or board of health to learn more. You can find contacts by clicking here.

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What if I think my system is failing?

Troubleshooting

If the amount of wastewater entering the system is more than the system can handle, the wastewater backs up into the house or yard and creates a health hazard.

You can suspect a system failure not only when a foul odor is emitted but also when partially treated wastewater flows up to the ground surface. By the time you can smell or see a problem, however, the damage might already be done.

By limiting your water use, you can reduce the amount of wastewater your system must treat. When you have your system inspected and pumped as needed, you reduce the chance of system failure.

A system installed in unsuitable soils can also fail. Other failure risks include tanks that are inaccessible for maintenance, drainfields that are paved or parked on, and tree roots or defective components that interfere with the treatment process.

Failure symptoms

The most obvious septic system failures are easy to spot. Check for pooling water or muddy soil around your septic system or in your basement. Notice whether your toilet or sink backs up when you flush or do laundry. You might also notice strips of bright green grass over the drainfield. Septic systems also fail when partially treated wastewater comes into contact with groundwater. This type of failure is not easy to detect, but it can result in the pollution of wells, nearby streams, or other bodies of water. Check with a septic system professional and the local health department if you suspect such a failure.

Failure causes

Household toxics

Does someone in your house use the utility sink to clean out paint rollers or flush toxic cleaners? Oil-based paints, solvents, and large volumes of toxic cleaners should not enter your septic system. Even latex paint cleanup waste should be minimized. Squeeze all excess paint and stain from brushes and rollers on several layers of newspaper before rinsing. Leftover paints and wood stains should be taken to your local household hazardous waste collection center. Remember that your septic system contains a living collection of organisms that digest and treat waste.

Household cleaners

For the most part, your septic system’s bacteria should recover quickly after small amounts of household cleaning products have entered the system. Of course, some cleaning products are less toxic to your system than others. Labels can help key you into the potential toxicity of various products. The word “Danger” or “Poison” on a label indicates that the product is highly hazardous. “Warning” tells you the product is moderately hazardous. “Caution” means the product is slightly hazardous. (“Nontoxic” and “Septic Safe” are terms created by advertisers to sell products.) Regardless of the type of product, use it only in the amounts shown on the label instructions and minimize the amount discharged into your septic system.

Hot tubs

Hot tubs are a great way to relax. Unfortunately, your septic system was not designed to handle large quantities of water from your hot tub. Emptying hot tub water into your septic system stirs the solids in the tank and pushes them out into the drainfield, causing it to clog and fail. Draining your hot tub into a septic system or over the drainfield can overload the system. Instead, drain cooled hot tub water onto turf or landscaped areas well away from the septic tank and drainfield, and in accordance with local regulations. Use the same caution when draining your swimming pool.

Water Purification Systems

Some freshwater purification systems, including water softeners, unnecessarily pump water into the septic system. This can contribute hundreds of gallons of water to the septic tank, causing agitation of solids and excess flow to the drainfield. Check with your licensed plumbing professional about alternative routing for such freshwater treatment systems.

Garbage disposals

Eliminating the use of a garbage disposal can reduce the amount of grease and solids entering the septic tank and possibly clogging the drainfield. A garbage disposal grinds up kitchen scraps, suspends them in water, and sends the mixture to the septic tank. Once in the septic tank, some of the materials are broken down by bacterial action, but most of the grindings have to be pumped out of the tank. Using a garbage disposal frequently can significantly increase the accumulation of sludge and scum in your septic tank, resulting in the need for more frequent pumping.

Improper design or installation

Some soils provide excellent wastewater treatment; others don’t. For this reason, the design of the drainfield of a septic system is based on the results of soil analysis. Homeowners and system designers sometimes underestimate the significance of good soils or believe soils can handle any volume of wastewater applied to them. Many failures can be attributed to having an undersized drainfield or high seasonal groundwater table. Undersized septic tanks—another design failure—allow solids to clog the drainfield and result in system failure.

If a septic tank isn’t watertight, water can leak into and out of the system. Usually, water from the environment leaking into the system causes hydraulic overloading, taxing the system beyond its capabilities and causing inadequate treatment and sometimes sewage to flow up to the ground surface. Water leaking out of the septic tank is a significant health hazard because the leaking wastewater has not yet been treated.

Even when systems are properly designed, failures due to poor installation practices can occur. If the drainfield is not properly leveled, wastewater can overload the system. Heavy equipment can damage the drainfield during installation which can lead to soil compaction and reduce the wastewater infiltration rate. And if surface drainage isn’t diverted away from the field, it can flow into and saturate the drainfield.

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Here are additional resources that will make owning a septic system easier:

  1. EPA Homeowner's Guide
  2. EPA Homeowner's Checklist
  3. EPA Introduction to Decentralized Wastewater Treatment (DWT): A Sensible Solution
  4. EPA DWT Can be Cost Effective and Economical
  5. EPA DWT Can be Green and Sustainable
  6. EPA DWT Can Protect the Environment, Public Health and Water Quality

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