Seasonal care

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Checking frozen septic systems

If an onsite septic system freezes during a cold winter it is important to know why and where the system froze. This will help determine if repairs, corrections or changes to the system are necessary to make sure it will operate properly in the future. The steps needed will depend on the type of system and where the freezing occurred. If the freezing problem was simply because of cold temperatures and/or lack of snow cover to insulate the system, it may just need to be checked for problems and perhaps minor repairs or improvements made.

However, some freezing problems are the result of problems with the design, installation or use of the system that may require significant repairs or changes to solve the problem. Other factors, such as excessively high or very low water use, can also be a contributing factor to the freezing problem. For more information about why systems freeze and measures to prevent freezing, please see the fact sheet entitled Freezing Problems with Onsite Sewage Treatment Systems.

There are four common locations where systems can freeze:

  1. Pipe from house to tank
  2. Septic tank and/or pump tank
  3. Pipe to soil treatment area
  4. Soil treatment area

It is important to determine where and why the system froze so corrective actions can be taken to avoid freezing in the future. A licensed onsite professional should be able to determine where the system froze if it is not obvious. Homeowners should also know where each component of the system is located to aid in problem solving and proper maintenance. After a system has been frozen and thawed each component should be checked.

1. Pipe from house to tank

If the pipe between the house and septic tank froze, two issues need to evaluated. First, make sure there are no leaking fixtures, such as toilets or faucets, or low wastewater generating devices, such as a high efficiency furnace, discharging into the system. Secondly, make sure the entire pipe has sufficient slope without any sags to assure water is draining into the septic tank (minimum of 1" drop in eight feet and a maximum 2" in eight feet). This slope must be toward the tank.

2. Septic tank and/or pump tank

When a septic tank freezes the baffles need to be check to verify that they are still in place and have not been damaged. The tank(s) should also be checked for cracks, although this occurs very rarely. Styrofoam, which is designed to be buried, can be placed over the tank to insulate it by removing the soil cover, placing 1-3 inches of Styrofoam and replacing the soil cover. If the tank was pumped out because of a freezing problem and this pumping was not done through the manhole (>20 inches in diameter) then proper maintenance of the tank was not performed. In this case the tank should be pumped on its normal 2-3 year interval from the last date of proper maintenance.

If there is a pump in the system, it should be inspected to make sure none the floats have not been damaged. The pump should be checked to assure it is pumping effluent and it will turn off and on as necessary. It is important that the pump is accessible at all times. This may require the installation of a riser to bring the access to the surface. Because bringing the manhole to the surface will allow more heat loss from the tank, it is a good idea to add Styrofoam under the manhole cover or place insulation (loose material such as straw, hay or leaves) over the top of the cover each fall.

3. Pipe to soil treatment area 

The pipe from the tank to the soil treatment area may have frozen for the same reasons as the pipe from the home (# 1). If so, the same remedies would apply. In addition, if there is a pump in the last tank, it is critical that when the pump shuts off, all the effluent drains back into the tank through a weep hole. A weep hole is typically a ¼ hole in the lowest portion of the piping in the manhole. This weep hole will drain water even when the pump is on. Two common problems in pump tanks are check valves that do not allow effluent to drain back and pumping systems designed for drainback through the pump. A licensed onsite professional can determine if a check valve is in place or if the effluent is draining through the pump.

4. Soil treatment area

If the soil or mound was soggy or wet before the winter, the system needs a thorough evaluation by an onsite professional to determine why it is not operating properly. If sewage comes to the surface while frozen in the winter, this creates a health risk to people or animals that can easily can come in contact with it. This problem is serious and must be corrected. If ignored after the freezing problem, sewage is likely to surface in this area in the future. The solution may be as simple as bringing in additional topsoil or a more extensive reworking of this part of the system. Checking the distribution system should also be done. In gravity situations drop or distribution boxes should be checked and in pressure applications the system should be verified.

If a drip distribution system froze, a licensed onsite professional trained to maintain the system should troubleshoot the system to determine if a problem exists. Common reasons for drip systems freezing include improper drainback and frozen air relief valves.

Freezing problems

Why might an onsite system freeze?

According to many onsite professionals, a winter of cold temperatures and little snow cover can cause freezing of onsite systems. Even in a normal Minnesota winter, freezing can occasionally be a problem. Identifying and correcting a potential freezing problem is far easier than dealing with a frozen system. Here are a few common causes of onsite system freeze-ups.

Lack of snow cover

Snow serves as an insulating blanket over the septic tank(s) and soil treatment area (trenches, drainfield or mound). Snow helps keep the heat of the sewage and the geothermal heat from deep soil layers. Lack of snow allows frost to go deeper into the ground, potentially freezing the system.

Compacted snow

Compacted snow will not insulate as well as un-compacted snow. Driving any type of equipment over the system compacts snow and sends the frost down deeper. Automobiles, snowmobiles, ATV's, foot-traffic, and livestock should stay off the system all year long but especially in the winter. Any time traffic over a sewer pipe, septic tank, or soil treatment area is anticipated, insulated pipe should be used.

Compacted soils

Areas that have compacted soils such as driveways, paths or livestock enclosures tend to freeze deeper, affecting septic system components that may be in the area.

Lack of plant cover

This often occurs in new systems installed late in the year where a vegetative cover could not be established before winter. The vegetative cover insulates the system and helps hold snow.

Irregular use of system

When homes or cabins are unoccupied for long weekends or extended periods of time, no sewage is entering the system to maintain sufficient temperatures to avoid freezing. This can also occur when very low volumes of sewage are being generated. In cases when only one or two people are living in a home, they may use only a small percentage of the designed flow for the system. This low usage may not be sufficient to keep the system from freezing. Frequent use, warmer water temperatures and greater water use are all important in cold temperature stress situations.

Leaking plumbing fixtures and furnace drips

When a fixture such as a toilet or showerhead leaks, it sends a small trickle of water to the system. The slow moving and thin film of water form caused by trickle flow can freeze within the pipe and eventually cause the pipe to freeze solid. Appliances such as high efficiency furnaces and humidifiers can also cause water to freeze in the pipes due to the small amount they discharge.

Pipes not draining properly

A common cause of freeze-ups are sewer pipes and pump lines that are not installed with proper fall (change of elevation), or pipes that settle or sag after installation. Any time a dip or low spot occurs in a pipe, sewage can collect and freeze. Pump lines can develop a dip right next to or above the septic tank as a result of backfilled soil settling from the excavation during the tank installation. All sewage needs to drains out of the pipe from a pump line.

Cold air entering the system

Open, broken and uncapped riser or inspection pipes and manhole covers allow cold air into the system and can cause the system to freeze.

Water logged system

If a system was hydraulically failing (e.g. water coming to surface or seeping out the side of a mound) it is a prime candidate to freeze. This effluent will freeze and prevent further effluent from entering the soil.

What should you do if your onsite system freezes?

If your septic system is frozen, your first step is to call an onsite professional. Unless the cause of freezing is corrected the system will refreeze next winter. If you have a pump and hear water constantly running in a pump tank (a possible indication of a frozen system) shut off your pump and call an onsite professional. This will likely be a pumper or an installer who can help determine the cause of the problem and offer solutions. The University of Minnesota Onsite Program web site is one place to go to locate a professional. Many pumpers and installers have devices called steamers and high-pressure jetters to try to unfreeze system piping. Other methods used to help fix a freezing problem include adding heat tape and tank heaters. Cameras can be sent down the pipes to determine where the freezing is occurring and if repairs are needed. If the soil treatment system is full of ice, or there is evidence of leaking, there is no need to thaw the lines leading to the treatment area, as it cannot accept liquid until the area is thawed in spring.

If it is not feasible to correct the problem or equipment is not available in your area, the only other option is to use the septic tank(s) in the system as a holding tank until the system thaws naturally. You will need to contact a pumper who will empty out the tanks when they are full on a regular basis .This can be very costly, especially with normal volumes of water use (50 to 75 gallons per person per day). Reduce water use by limiting the number of toilet flushes, taking short showers, using the dishwasher at full capacity, limiting running water to get hot or cold and doing laundry at a laundromat. It is smart to find the cause of the freezing problem so that it can be addressed in the spring, preventing future freeze-ups. Then preventative measures can be added to the system such as adding insulation around the tank and pipes or adding additional cover.

There are many misconceptions about how to deal with a frozen onsite system.

  • Do not add antifreeze, salt or a septic system additive into the system.
  • Do not pump sewage onto the ground surface.
  • Do not start a fire over the system to attempt to thaw it out.
  • Do not run water continually to try to unfreeze system.

What can you do to prevent your onsite system from freezing in the future

Depending on your system, location, and water use, you may never have a freezing problem. However, there are several steps that you can take if you are concerned about your onsite system freezing. Here are some precautions if you have had a past problem or are concerned about having a future problem. It is not necessary to do all of these, but you may pick and choose based on your situation:

  1. Place a layer of mulch (8-12 inches) over the pipes, tank and soil treatment system to provide extra insulation. This mulch could be straw, leaves, hay or any other loose material that will not compact and stay in place. This is particularly important if you have had a new system installed late in the year and no vegetative cover has been established. If your system is currently frozen ignore this step, as it will delay thawing come spring.
  2. Let the grass in your lawn get a little longer in the late summer/fall over the tank and soil treatment area. This will provide extra insulation and help hold any snow that may fall.
  3. Use water; the warmer the better if you feel the system is starting to freeze. The Onsite Sewage Treatment Program is usually an advocate of water conservation, but if freezing is a concern, increasing low use to a normal water use can help the system. This includes spreading out your laundry schedule to possibly doing one warm/hot load per day, using your dishwasher and maybe even taking a hot bath. DO NOT leave water running all the time, as this will hydraulically overload the system.
  4. If you know you are going to be gone for an extended period, plan accordingly. This could include having someone use sufficient quantities of water in the home regularly or pumping out your tank before leaving. If you live in an area with a high water table, you should only pump out the tank if the tank was designed for high water table conditions . If a tank is left full for several winter months, the sewage will get very cold in shallow tanks and can even freeze. If you then return home before temperatures start to rise, the effluent leaving the tank will be cold. By starting with an empty tank, you can then start fresh with warm effluent. If you use a cabin on a limited basis during the winter months, this may be a good idea as well.
  5. Fix any leaky plumbing fixtures or appliances in your home. This will help prevent freezing problems and help your system work better year round.
  6. If you have appliances that generate very low flows such as high efficiency furnaces, you can put a heat tape in the pipe, and while on vacation have someone come by and run warm water for a while. Alternately, you could install a small condensate pump that holds and discharges 2 gallons per cycle.
  7. Keep all types of vehicles and high traffic people activities off of the system. This is a good rule to follow year round.
  8. Make sure all risers; inspections pipes and manholes have covers on them. Sealing them and adding insulation is a good idea. Insulation may be added during construction particularly if the top of the septic tank is within 2 feet or the surface.
  9. Keep an eye on your system. If any seeping or ponding occurs contact an onsite professional to help determine the cause and remedy.
  10. Add more insulation to your system. This could include replacing pipe with insulated pipe, adding styrofoam over septic tanks or adding more soil cover.

The problems with high efficiency furnaces, water softeners and iron filters discharging into onsite sewage treatment systems

High efficiency furnaces

These furnaces operate at a high efficiency and therefore save on energy use. One of the results of the heating process is that condensation occurs in the unit. When this condensation builds up water slowly trickles out of the unit and into the plumbing that is often connected to an onsite system. This water can cause freezing problems in the onsite system because of the slow steady flow. In addition, this water is clean and therefore does not need to be treated. When the furnace is in operation this water typically trickles out of the unit totaling 5-10 gallons on a cold day.

Water softeners and iron filters

Water softeners, reverse osmosis, and iron filter recharge water adds a large volume of water to the system - typically 30 to 80 gallons per cycle. This is water that does not require treatment as it does not contain viruses or bacteria.

A growing concern with water softener recharge water is that it may cause an increase in the amount of solid material staying suspended in the liquid layer (effluent) in the septic tank ending up in the drain field trenches or a mound. These solids may shorten the life of the soil treatment system increasing the chance of drainfield or mound failure. This water softener discharge concern has conflicting results in research studies, but it does appear that scum layers are often absent in tanks where the water softener recharge water enters the septic tank. Iron filters typically take in-soluble iron and convert it to soluble which can result in an accumulation of sludge. This sludge has the potential to plug out soil.


  1. Be sure to check with the local government unit before any changes are made to the onsite system.
  2. If only the furnace condensate water is being added this can go into the onsite system but a sump or other device to collect the water must be used if the home is left vacant for extended periods of time so water is not trickling out, causing freezing problems.
  3. Route your furnace, water softener and iron filter discharge out of the onsite system. Note: The soil treatment area where the water is being dispersed must meet setbacks to the water supply well.
    • Route the water to an old onsite system no longer being used for sewage treatment. Be sure no sources of sewage are allowed to enter this system.
    • Install a small separate section of drainfield (trench or bed) to deal with this water. In most cases 20-50 feet should be sufficient. Since this is not sewage it does not need to have three feet of treatment, but to assure the effluent will disperse it should not be set in the watertable. Consult a septic professional to determine the proper siting.
    • If the water includes an iron filter a septic tank should be installed to attempt to settle out some some of the iron sludge.  There is concern that over time some of the soluble iron may plug up the soil so replacement of the soil dispersal system may need to occur over time.  The timer period for replacement will depend on the method of iron removal and the amount of iron in the water.
  4. If rerouting is not an option, a good solution for everyone is to minimize the amount of water used by the softener, osmosis system or iron filter.
    • Reduce the total volume of water used in the home.
    • Read your manual for your water treatment device and use it according to the manufactures requirements.
    • Only treat water used inside the dwelling and not the water used outside the dwelling for irrigation, car washing, etc.
    • Adjust the water softener or iron filter to recharge less frequently. Adjusting the frequency can be done by lengthening the time between recharges on a timed unit or increasing the volume of water passing through the unit before recharging on a metered unit.
    • Add heat tape in the pipe receiving the furnace discharge. This will help prevent freezing.

Winter septic tank pumping

In general, cleaning of septic tanks is not recommended in cold climates during the winter months.  Winter’s arrival can vary year to year, but a good rule of thumb in Minnesota is to avoid pumping from November – April.  Below are the most common problems associated with winter pumping.

  1. Depending on the size of the family living in the home it could take days or even weeks for the septic tank(s) to fill back up. The typical person uses approximately 60 gallons per day. If two people were living in a home it would take eight days for the tank to be full. During these eight days no wastewater would be traveling out through your septic tank and out to the soil treatment system. This could result in your septic soil treatment area freezing and your septic tank requiring pumping out for the rest of winter.
  2. Often the lids on septic tanks are buried. Once frost gets into the soil it is very difficult to dig down to the lid. On a side note, it is recommended that these lids be extended to grade to facilitate pumping. Septic tanks can only be properly maintained by accessing the lid. Newer septic tanks have maintenance lids to grade that are insulated. Shallow tanks are insulated too as shown in the picture at right. 
  3. If the maintainer who cleans your septic tank typically land applies the septage versus taking it to a wastewater treatment plant, it may be more challenging or not allowed if the soil is frozen.                                            
  4. There are bacteria in your septic tank that work to breakdown the wastewater. It takes time to get the bacteria up to full speed after a tank pumping. This will happen more rapidly under warmer conditions. In addition, they do not work as well when they are cold which is more likely after pumping.


Although winter pumping is not generally recommended there are few times it may be the correct course of action discussed below.  

  1. There is an emergency related to the septic system that involves sewage backing‐up into your home, sewage coming to the surface in your yard, or your septic pump needs replacement.   
  2. If you have a cabin or home that will have limited use during the winter, the septic tank can be pumped and then gradually filled over the winter with no wastewater leaving the septic tank. If the tank is located in an area with a high water table, tank buoyancy should be evaluated prior to pumping the tank. If a septic tank is left full with low uses over the winter months, the sewage will get very cold, and can even freeze.      

Created November 2019       

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Start your septic system out on the right foot for spring

Seasonal cabin owners are always anxious to open the cabin in the spring. Here are some tips to get your septic system off to a good start for the coming summer.

Watch the snow melt – where it pools and runs. If going over your drainfield or tank, channel it away – your system does not need added stress from the surface. As the ground thaws, watch the tank and drainfield areas for surfacing. Look for areas that stay wet, water standing on the surface and grass greening up earlier than other areas. These symptoms can indicate a problem in the drainfield or the piping to the system. It could be a sign of freezing that didn't appear during the winter months.

Take a walk around your system. How close are the trees? Remember, hardwoods such as oaks and maples have a root system that extends as far out underground as the canopy of the tree does above. Are there water-seeking trees such as willows nearby? Their roots will extend out searching for available water, and can quickly invade your drainfield area.

When doing your spring cleaning, keep an eye on how many chemical products you use. Limit the amounts and use more elbow grease. Antibacterial and bleach cleansers do not do a better job than more natural products. Read the product labels; anything listing chlorine includes bleach. For many jobs such as dusting or wiping walls down, plain water is just as effective.

Created March 2007

Protecting your septic system from flood damage

According to University of Minnesota Extension and the Onsite Sewage Treatment Program (OSTP) staff, if you have a septic system that is in the area affected by the recent flooding, there is potential for damage to the system. However, you can take action after the flooding to minimize the damage. When floodwaters cover your septic system it should not be used. If the soil treatment area or ground above your septic tank floods, your individual sewage treatment system is not working.

If your system was flooded

The OSTP staff recommends the following steps to help your system recover:

  • Contact a licensed tank pumper/maintainer to pump the tank(s) as soon as possible after the flood recedes and prior to resuming use of the system. Be sure to pump both the septic tank and the pump/lift station (if you have one). Silt and other debris may have collected in your septic tank while it was under water which could ultimately find its way to and damage the soil treatment area. Additionally, a variety of substances such as pesticides, petroleum products and other contaminants may have entered the tank. These contaminants could be detrimental to the beneficial bacteria in both the tank and the soil treatment area and therefore need to be removed. However, it is not advisable to leave the septic tank empty after pumping if the soil around the area of the tank(s) is saturated; this can cause the tank to "float" toward the ground's surface if the soil's water pressure remains high. If you have this concern, consult a licensed tank pumper/maintainer.
  • Locate and protect the soil treatment area from compaction by keeping all traffic off the area. Often considerable traffic takes place around a flooded home as flood cleanup and home restoration occur. This traffic could include but not be limited to foot traffic, debris piles, dumpsters, and heavy equipment. Compaction reduces the capacity of your drainfield to treat wastewater and could lead to the early failure of your entire system.
  • Check electrical connections for damage or wear before turning electricity back on.
  • Check that the septic tank manhole cover is secure and that inspection ports have not been blocked or damaged. Check for animal damage or intrusion in the soil treatment area.
  • Check the vegetation over your septic tank and soil treatment area. Repair erosion damage; sod or reseed as necessary to provide a good plant cover. You may need to mulch the area to provide insulation if the grass has not become well established before winter.
  • Inside your home, be sure to disinfect thoroughly if sewage backed up into the house or garage. Disease-causing organisms (pathogens) in wastewater can cause serious illness, such as dysentery, hepatitis, and other waterborne illnesses. However, avoid flushing these disinfectants into drains which empty into the septic system. The disinfectants could be detrimental to the beneficial bacteria in both the tank and the soil treatment area. If you need to chlorinate your well, follow the University of Minnesota instructions fully. Do not allow the bleach to enter your septic system.
  • If after the floodwater has receded from the soil treatment area and the surrounding soil has had a chance to dry, but the soil treatment area still will not accept effluent from the septic tank, the soil treatment area pipes or soil might be "plugged". At this time the homeowner should consult a licensed septic system professional.
  • If homeowners have additional concerns they should discuss them with a local septic system permitting authority or a licensed septic system professional.
  • If you have a drainfield that has not been flooded, but is soggy due to heavy rain, minimize water use within the home. The additional water added due to household use can cause poorly treated sewage to surface in your yard or raw sewage to back up into your house. You can minimize water use within the house in a variety of ways, including taking shorter showers or baths and not doing laundry until the soil treatment area begins to dry out.

If portions of your system were destroyed

Often flood waters can cause components of septic system to be partially or completely washed away. The owner of such a system should not assume that soil or other "fill" can be added and new system components constructed. The homeowner should contact a licensed septic system professional or the local septic system permitting authority to discuss options that will meet state and local codes.

Heavy rains can cause slides to partially or completely cover septic system components with rock, mud, or silt. These slides can affect the operational integrity of the system, especially the soil treatment area. Care needs to be taken for slide debris removal from the area on or around a septic system in order to protect system components, taking special care to keep vehicle and equipment traffic off the soil treatment area to avoid compaction. Once again the homeowner should contact a licensed septic system professional or the local septic system permitting authority to discuss options that will meet state and local codes.

If your drainfield is saturated or has standing water not caused by flooding or heavy rain, you may have a long-term problem. Contact a licensed septic system professional or the local septic system permitting authority to discuss options that will meet state and local codes.

Septic system cleaners

The general rule of thumb about septic system starters, feeders, cleaners and other additives is: If they are safe to use, they are probably not effective; and if they are effective, they are probably not safe to use. There is no quick fix or good substitute for proper septic tank operation and regular maintenance.

A "starter" is not needed to start bacterial action in the septic tank. There are numerous bacteria present in wastewater. It is also not necessary to "feed" the system with additional bacteria, yeast preparations or other home remedies. We feed the system every time we use it.

Septic tank '"cleaners," intended to remove solids from the tank, will probably damage the soil treatment system. Many additives agitate the solids that should float to the top or settle to the bottom of the tank. This agitation suspends the solids. It allows them to be flushed into the drainfield. There they clog pipes and soil pores, leading to partial or complete failure of the system. This can result in the need for a costly replacement of the soil treatment system.

Other additives, particularly degreasers, may contain carcinogens. These cancer-causing agents flow directly into the groundwater with the treated sewage.

Minnesota Rules Chapter 7080, titled "Individual Sewage Treatment Systems Program," bans septic system additives which contain hazardous materials. In addition, it specifies additives must not be used to reduce the frequency of proper septic system maintenance.

EPA or USDA approval of additives means the product contains no hazardous materials. It does not mean the product is effective at what the manufacturer claims it will do.

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Control water use

Repair all leaky faucets, fixtures and appliances immediately. Check toilet bowls for leaks: at night, put some food coloring in the toilet tank. In the morning, inspect the bowl. If colored, there is a leak between the tank and bowl.

  • Install low water use fixtures and appliances (especially toilets and shower heads).
  • Do not empty roof drains and sump pump water into the septic system; channel away.
  • Wash only full loads of clothing and dishes.
  • When replacing a washing machine, take a close look at the front loading, and water efficient top loading machines. These machines save a great deal of water over older washers.
  • Reduce length of showers and number of toilet flushings.
  • Reroute water softener and iron filter recharge water out of septic system.
  • Spread water use as evenly as possible throughout the day and week, especially laundry. 

Eliminate harmful products from system

Use liquid laundry detergents and gel dishwashing detergents. This minimizes the non-organic solids sent to the tank. Read labels carefully – many gel dishwashing detergents are high in phosphorus content; avoid these products.

  • Reduce/eliminate use of harsh cleaners, disinfectants, detergents and bleach, including laundry detergents. Increase elbow grease, decrease cleaners.
  • Avoid the use of anti-bacterial soaps. They are not necessary for cleanliness, and destroy good bacteria in the tank and soil treatment area.
  • Dispose of solvents, paints, unwanted medications through other means such as hazardous waste disposals and exchanges. Return un-used medications to the pharmacy if possible.
  • Keep grease, lint, food particles, cigarette butts, paper towels, disposable diapers, coffee grounds, plastic and other solid products out of the system.
  • Install an effluent filter, preferably one with an alarm on the outlet pipe of your septic tank. This will catch washing machine lint, small particles that stay in suspension in the liquid and other matter. These must be maintained and cleaned regularly. One type is installed and maintained by your pumper. Another type is installed and maintained by the homeowner.


It is not necessary to use additives to enhance the performance of a properly operating septic system. If bacterial activity is low, it is because disinfectants and other products are killing the bacteria. Reducing or eliminating the use or disposal of these in the system will allow the bacteria to re- establish. Some additives cause solids to become suspended in the liquids. These solids will end up in the drain field, causing significant damage. Starters, feeders and particularly cleaners are unnecessary, and may be harmful to your system.

Cleaning/pumping the septic tank

The septic tank must be cleaned or pumped regularly to remove all solids. The recommended time is at least every three years. Refer to the Septic Owner's Guide for a chart to determine a pumping schedule based on number of people in the home, size of the system and water use habits.

  • Always have the tank(s) cleaned through the manhole (20 to 24 inch opening). The inspection pipes are just that - for inspection. These are the white 3 - 4" pipes at the end of the tank and drain field.
  • Flushing and back flushing is the most common method of agitating solids so they can all be removed.
  • Inlet and outlet baffles should be inspected to be sure they are in place and functioning properly.
  • If you have an effluent filter, inspect and clean regularly.
  • The soil treatment area should be inspected at the time of pumping. 

Pumps and filters

All pumps and motors should be routinely checked for proper operation.

  • Replace weak or faulty pumps and motors.
  • Effluent filters should be cleaned or replaced regularly.
  • Alarms on pumps and filters must be attended to immediately. 

Vegetative cover

Mow but do not fertilize or water plantings over the drain field/mound.

  • Maintain stands of appropriate plants on constructed wetland sites
  • Any shallow rooted grasses or flowers may be planted over a drainfield or mound. Avoid deep rooted plants, shrubs and vegetables over your system. If native prairie grasses are used, manage by mowing - do not burn over this area.
  • Be sure water -seeking trees such as willows are located far away from the system.
  • Stop cutting the grass over the soil treatment area a couple weeks before the rest of the lawn. The extra growth will help insulate the area, and will help prevent freezing.

Protect the soil treatment area

Keep all foot and vehicle traffic off the tank, pipes and soil treatment area (drainfield or mound). The only exception is the lawn mower. Mounds and drainfields are not 4-Wheeler jumps, walking paths, or for use by snowmobiles or cars.

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Winterizing the pipes

  • Do not add automotive antifreeze, salts or any other additives to your plumbing. 
  • If you leave the water on for the winter, be very sure that there are no leaks or drips. This constant, low flow of water can cause septic system freezing. This is common with high efficiency furnaces. 
  • Even if the heat is left on, it is a good idea to drain water supply lines. Shut off the water where it enters the house and drain all lines. Drain the pump and then run a couple of seconds to be sure all water is out of the lines. Drain the system by opening all the faucets, leave faucets open. Completely drain the pressure tank. Flush toilets and add RV antifreeze to the tanks at the recommended dilution ratio. Check flexible hoses in sinks and bathtubs to be sure they are drained completely. Remove and drain inlet hoses for the dishwasher and clothes washer. Clear the water valve by starting the machine for a few seconds, then drain the tub. Remove the drain hoses, drain completely. Disconnect the electrical supply to the pump, water heater, softener, washer and dishwasher. Drain the water heater and water softener with a hose after power is disconnected. RV antifreeze can be added to traps in sinks, bathtub and shower drains, washtubs, floor drains and sump pumps. In the spring, re-connect all hoses and flush the lines out before using again. 


If you have a high efficiency furnace that is left on for the winter, be sure there is no water drip into your system. Freezing can result. Re-route the drip water to a floor drain, bucket or other source that does not enter the septic system at all, or enters in larger amounts. This water does not harm the septic system, but entering in very small amounts causes a trickle of water, which can freeze more easily. If shutting off the furnace, drain all water from forced hot water and steam systems unless the system contains antifreeze. If that is the case, call a plumber for assistance. If leaving the furnace on, it is a wise idea to conserve energy by installing a low-heat thermostat that will maintain the cabin at 40 degrees. 

Cleaning/pumping the septic tank

Consider pumping the tank if closing the cabin for the winter, or if it will only be used a few times during the winter. If you live in an area with a high water table, you should only pump out the tank if the tank was designed for high water table conditions. If a tank is left full but the system is not used for the winter months, the sewage will get very cold, and can even freeze. If the cabin is opened before temperatures in the soil start to rise, the effluent leaving the tank will be cold. By starting with an empty tank, you can then start fresh with warm effluent, which is desirable in the soil treatment area.

Vegetative cover

Stop cutting the grass over the soil treatment area in mid-September. The extra grass length will help capture snow, providing insulation over area. This can help prevent freezing.

Protect the soil treatment area

Keep all foot and vehicle traffic off the tank, pipes and soil treatment area (drainfield or mound). The only exception is the lawn mower. Do not plow snow off the area or store plowed snow over the drainfield.