Septic Systems

Septic Systems

In Ontario alone, there are more than 1.2 million on-site wastewater treatment systems.  This term is used to describe all the various types of systems that treat wastewater with the vast majority being conventional septic systems.

Septic systems are a good way to treat waste – as long as they are functioning properly.  Faulty septic systems can be extremely hazardous since improperly treated effluent can harm both your health and the health of the environment.


What Is a Septic System?

Because wastewater can contain bacteria, viruses and other contaminants, it needs to be treated before it is released back into the environment. A properly functioning septic system uses natural processes to treat the contaminants so they will not harm the environment or human health.  Septic systems have two main components: the septic tank and the leaching bed.  Both components use a combination of physical, chemical and biological processes.


Waste to Water

 Step 1:  Raw sewage moves from your house or cottage into the septic tank.

Step 2 & 3:  In the tank, the sewage flows through a series of chambers where it separates into solid portions, which remain in the tank to break down, and liquid portions (effluent), which move to the leaching bed. Beneficial bacteria work to break down the solid portions (known as the scum and sludge layers).

Step 4:  The partially treated effluent leaves the septic tank when new wastewater flows into the tank.

Step 5:   The effluent moves through a distribution system to the leaching bed (tile bed).

Step 6:  The effluent reaches the leaching bed and flows through a series of perforated pipes.

Step 7:  Some of the effluent is drawn upward and absorbed by the grass and plants covering the leaching bed.  Gravity then carries the rest into the soils, which filter the remaining pollutants from the effluent.  Bacteria found in the soil then breaks down the toxins remaining in the effluent.  The effluent travels down from the soil until it reaches the groundwater and is reconnected with the water cycle.


Approval Process

If you are looking to install a new or replace an old septic system it must meet requirements outlined in the Ontario Building Code and an approval from your township must be obtained prior to the installation of the system.  Once completed it must be inspected before filling takes place. Refer to the contact page for information on how to contact your township on further approval information.

In shoreland areas it is particularly important to maintain your septic system properly because soil and water conditions near shore may make the system less efficient in treating wastewater. Incomplete treatment can result in health risks for you and water quality problems.

The role soil plays is a vital one – 40% of the wastewater treatment happens in the septic tank, but the remaining 60% of the treatment happens in the soil.

 Why Are Septic Systems a Problem? 

Potential health risks are the most serious concern related to failing septic systems.  Hepatitis, dysentery, and other diseases may be spread by bacteria, viruses, and parasites in wastewater.  These disease-causing organisms, called pathogens, could make near shore water unsafe for recreation.

Inadequate treatment can also allow excess nutrients to reach your lake or stream, promoting algae or weed growth.  Algae blooms and abundant weeds not only make the lake unpleasant for swimming and boating, but they also affect water quality for fish and wildlife habitat.  As plants die, settle to the bottom, and decompose, they use up oxygen that fish need to survive.

 If too many solids escape from the tank out to the leaching bed, the entire system will ultimately clog up.

There are several types of septic tanks: steel, concrete, plastic or fibreglass.  If you do not already know what type of septic tank you have you should find out and have it inspected for decay.


Steel Tanks

Steel tanks are only present in systems 35 years or older.  They are no longer legal to install.  They have a simple structure: a single one-chambered tank with inlet and outlet pipes.  Since they have no special mechanisms to slow the water down, they tend to allow much more suspended solids to escape than a more modern design.

In many cases if you have system that is forty or more years old and you have not had to have the system pumped, this is often the reason; likely your tank has rusted out and effluent is leaking directly into the ground.


Concrete Tanks

Concrete tanks have been in use for about forty years, and are by far the most common type of tank. They usually have a more sophisticated design than steel tanks.  Concrete tanks include several methods to slow down water movement:

  • A partition wall dividing the tank into two chambers.  The wall has small openings halfway down to allow the water to pass through
  • ‘Baffles’ which are concrete slabs suspended from the roof of the tank hanging halfway to the bottom
  • ‘T’ shaped entry and exit pipes

The weakness of concrete tanks is their tendency to deteriorate over time.  The action of the water will slowly break down the concrete.  The baffles will often fall in after approximately thirty years, the tank may often start to leak, and even the partition wall may eventually collapse.  If you use harsh cleaning chemicals, they can cause this process to happen much quicker.


Plastic and Fibreglass Tanks

Plastic and fibreglass tanks are usually two-chambered, and have a similar structure to concrete tanks.  Plastic/fibreglass tanks are relatively light, and are often used in remote locations where the tank has to be transported in.  However, they are more fragile than other tank types and have been known to break if the ground shifts.


Effluent Filters

Effluent filters are strainers that are installed into the outlet pipe from the tank.  They are not present in every tank, but they are strongly recommended.  The end result is less stress on the leaching bed.  The filters can be added to new systems, or retrofitted to older systems.

Effluent filters are easy to maintain.  Once a year, you just slide the filter out and wash it off with a garden hose over the tank.  Some filters even come with an alarm that will sound when they need cleaning. Effluent filters are highly recommended in prolonging the life of septic systems.  The filters remove 90% of the suspended solids that would have otherwise moved to the leaching bed.

The Importance of Soil

The soil filter is the last line of defence for breaking down any remaining bacteria, viruses, and other contaminants in the wastewater before it reaches ground and surface water.  As the effluent moves through the soil, the solid particles and bacteria in the effluent are caught in the soil pores.  As the effluent passing through the soil moistening and adding nutrients under the leaching bed, soil bacteria, colonize this area.  These ‘good’ bacteria are hard at work throughout the soil removing harmful bacteria, viruses and other contaminants.


Maintaining Septic Systems

The maintenance and care of your septic system is your responsibility.  You control what goes into it and how well it is maintained.  If a septic system is not properly maintained, it is more susceptible to malfunction.

Because the wastewater from a failing septic system can contaminate your well, your neighbour’s well and the shoreline environment, a failing septic system is not just your concern, but a concern for everyone and everything that uses the area.  If a property owner notices a problem, it is important to deal with it right away for the sake of everyone’s health.


How Can you Maintain your System to Avoid All of the Problems and Dangers Associated With a Faulty System?  

The first step is to be familiar with your system.  You need to know where the tank and bed are, what type of a system it is, and keep a written history of when it was installed, pumped, inspected, etc.

Aside from knowing your system, there are four main things you can do to properly maintain it:

 1. Regular Pump-Outs

The easiest and most important thing is to have the tank pumped out on a regular basis.  The great majority of system failures happen because the tank wasn’t pumped often enough.  Depending on the use and size of your septic system you will want to have your system pumped every 3 to 5 years.

2. Regular Inspections

It is important to inspect a septic system regularly.  A good opportunity would be when the tank is being pumped out.  At this point you should take the opportunity to:

  • Check the scum and sludge depth
  • Inspect the structure of the tank and baffles, looking for any large cracks or deterioration
  • Check the fit of the access lids and coordinate repairs as necessary.  The lids should fit firmly into the receiving grooves of the tank and should not be cracked or chipped.
  • Listen for water running into the tank once it’s been emptied.  If you hear water entering the tank from the house, when no one is using any water, this can indicate leaks or a running toilet.  Water running into the tank from the sidewalls or top of tank can indicate cracks or breached seals.  Water running into the tank from the outlet pipe can reveal substantial problems with the leaching bed.  The problem could be as simple as a blocked leader, header pipe, or as complicated as a malfunctioning, saturated bed.

If you are unsure or unable to inspect your septic system yourself, you can hire a professional to do so.  There are a number of people who can do this, including a septic inspector, a licensed contractor that installs or repairs septic systems, or a representative of a firm that pumps out septic tanks.

 3. Protect the Leaching Bed

The leaching bed is a sensitive area of the septic system.  The breakdown process in this area involves both bacteria and soil.  When these components are compromised or removed, the system does not completely treat the wastewater running through it.

You need to:

  • Avoid compacting the soils or damaging the distribution pipes in the leaching bed by keeping heavy machinery (like cars) and heavy foot traffic off the leaching bed.  Compacting the soil can crack the distribution pipes, when cracked, greater volumes of effluent can be released into the leaching bed, saturating and ultimately clogging it.
  • Avoid saturating the leaching bed by watering the lawn over the bed.
  • Keep trees away from the septic system especially ones like:Willow, Birch, Poplar and Cedar that have creeping roots.

 4. Control Inputs

Another important action is to control the volume of both liquids and solids that they put into the system.  As far as water goes, Canadians are among the world’s biggest wasters of water.  On average we use 340L of water per day.

It is recommended that you:

  • Install water saving devices (i.e. water saving taps, showerheads, toilets and appliances) to significantly reduce the amount of wastewater entering the system.  This will greatly reduce the chance of the system being overloaded and contaminating ground and surface water.
  • Practice water saving techniques: don’t leave the tap running unnecessarily (e.g. shaving, brushing teeth, doing the dishes).  Fix leaky taps or running toilets right away; a tap that drips can waste up to 55 litres in 24 hours.  Use dishwashers and washing machines only when fully loaded, and spread loads out over the week.
  • Avoid using commercial cleaners and opt for the more environmentally friendly alternatives that can be found at health food stores.  Chemical cleaners, solvents, antifreeze and cigarette butts all contain toxins that will kill the beneficial bacteria in a septic system.  These bacteria are required throughout all of the stages of the treatment process.  Without them, your system becomes useless.
  • Reduce the amount of solids that have to be broken down.  Items that normally go in the garbage should not be added to wastewater; a good rule of thumb is ‘if you didn’t produce it, it shouldn’t be going down your system’. Fats, oils and greases can clog pipes and cause the system to back up.  Garburators and other systems that add solids should be avoided if at all possible.


Many property owners wonder if they should be using septic additives in their systems, but you should avoid using these additives as they are not effective.  There are 3 main types of additives.

  1. 1.       Starters are often advertised to be used in a new system or in a system that has just been pumped to get the bacteria going again.  In reality, one use of the toilet will provide enough bacteria to get the system going again. The additional bacteria won’t harm the system; it will just be an unnecessary cost.
  1. 2.       Feeders are advertised as adding food for the bacteria to increase the rate of activity.  In reality if the rate of bacterial activity in the system is low, it’s probably because too many disinfectants or cleaning products are being put down the drain; which kill the bacteria.  By limiting the use of these cleaners, bacterial activity will be restored and returned to normal.  The addition of feeders won’t help or harm the system, but they’ll cost you unnecessary money.
  1. 3.       Cleaners are chemicals that claim to clean the tank and pipes, and increase the time between pump-outs.  These chemicals may clean the grease from the pipes, but they’ll also kill the bacteria.  They may also cause solids in the tank to mix with the liquids and become re-suspended.  If this happens, the solids will flow out into the septic drainage pipes, which will inevitably clog the system.  By trying to save $100 for the pump-out, you may be causing thousands of dollars in repair costs.


Why Septic Systems Fail

Failing septic systems are an unfortunate reality.  In fact, it is estimated that over half of all the systems inOntarioare failing to some extent.  No matter the type of system or its age, all systems run the chance of malfunctioning.  Even new systems can malfunction.  There are a number of reasons why this might happen, but most are preventable.

If you are experiencing a problem with your septic system, the first step is to follow the proper maintenance procedures that are listed above.  If you follow the proper maintenance process and still have a problem occur, then there may be a structural problem with the system.


Improper Siting or Installation

Many failed systems inOntarioare the results of poor siting or improper installation.

When installing a new septic system, it is important that you ensure that the contractor you use is certified to install septic systems beforehand.  The local Health Unit carries a list of contractors who are fully aware of provincial regulations and are familiar with the requirements for proper siting and installation.  Throughout the installation process, an official septic system inspector must inspect the work.  This person will visit the site a number of times to ensure that the system is up to code before issuing a permit.   The inspector will insure that:

  • The system is the proper size for the load
  • The system is far enough away from your and your neighbour’s well, as well as any other distance restrictions
  • The distribution box is working
  • The leaching bed is composed of the appropriate layers of filter material (gravel, etc.)
  • The pipes are laid into the leaching bed properly (level surface-no angles)
  • The leaching bed soil has been covered in sod or planted with grass seed to prevent soil erosion
  • The leaching bed is not buried too deeply. (The backfill over a leaching bed cannot be deeper than 0.6m and must be permeable to allow oxygen to reach the bed. The soil bacteria which break down the effluent require oxygen to live)


Undersized Tank or Leaching Bed Area

Other problems may arise when the tank or system is not the proper size for the volume of wastewater being produced.  When the tank is too small for the volume of wastewater, the solids and scum layers in the tank build up too quickly, flow out into the bed and clog it.  A leaching bed too small for the load placed on it will simply clog within a few years.

The larger the volume of waste water, the bigger the tank and bed need to be.  If you have plans to build a new bathroom or bedroom, purchase additional water-using appliances, or to convert a seasonal cottage into a full-time residence, you will need additional septic capacity.  If the tank is too small, you can make some improvements to the system like adding on an extra tank, adding an additional filtering unit, or expanding the leaching area.


High Groundwater Table

It cannot be overemphasized that the high groundwater table must be carefully established prior to installation.  If there is not at least 0.9m of unsaturated soil between the base of the absorption trench and the high groundwater table, the effluent may not be adequately treated before it rejoins the water cycle.  Once it reaches the water table, viruses and bacteria like E. coli – not to mention all the chemicals that were put down the drain – can move great distances and contaminate aquifers.

You may discover too late that the water table is too high for the leaching bed to work properly, or sometimes changing environmental factors will cause the water table to rise.  For these situations, purchasing a composting toilet to remove sewage from the equation is an effective solution.  The existing septic system will be sufficient to treat the household grey water (wastewater from sinks, showers, etc.).


Distribution Box or Header is off Level

Sometimes the distribution box can settle differentially to the rest of the system (systems with pumps are especially prone to this).   This is typically the result of poor compaction of the bedding material directly beneath the distribution box.

A distribution box that is off level will cause effluent to flow unevenly to all parts of the bed so that often only one part of the bed receives effluent.  When this happens the soil under the section receiving all the effluent will clog prematurely.  In these situations the distribution box will need to be reset by a licensed septic installer.


Physical Damage

The tile bed can be damaged or crushed if vehicles are driven over or parked on it.  The roots of trees and deep-rooted shrubs such asWillowand Dogwood can also cause significant damage.  It is recommended that a distance of 5m around the tank is kept clear from trees and shrubs and at least 10m from Poplar andWillowtrees.  Ensure that there is a vegetated buffer between your leaching field and a lake or stream.  This will absorb excess nutrients, help retain water, and prevent erosion.


How to Tell if There is a Problem

Unfortunately it isn’t always easy to tell when there is a problem with a septic system.  Since most of the components are buried underground, it is most common to discover a problem long after the breakdown has occurred.  However, there are a few symptoms that may indicate there is a problem with the septic system:

  • Look for patches of abnormally healthy looking grass or vegetation on the leaching bed. These patches may be doing well because of wastewater nutrients sitting in soil just below the surface.  This is a sign that the leaching bed is full.  Normally these nutrients would filter down through the soil with the effluent, making room for more effluent to move through.  Patches of lush green grass can also indicate that there is too much wastewater being pushed through the system.
  • If the ground over the leaching bed is soft or spongy, it could be an indication that the leaching bed is saturated (full).
  • Pools of dark water on the surface point to the same problem.
  • When toilets and drains start backing up or they make gurgling noises and take a long time to drain, it can indicate that there is a blockage in the system or that the system is full.
  • Odours are also good indicators that something is wrong with the septic system.  When the beneficial bacteria that break down the contaminants in the soil are drowned out or suffocated by a saturated leaching bed, another bacteria group takes over. These (anaerobic) bacteria can work in the absence of oxygen but they produce a strong odor when breaking down contaminants. This odor can be a warning sign of a saturated leaching bed.  Odors can also indicate that the cover of the tank is not completely sealed or buried.
  • Foul smells in the house can indicate the house-to-tank pipe is broken and wastewater is leaking around the foundation of the house.  The foul smells can also accompany wastewater that backs up into the house.


The Dangers of a Failing Septic System

There are a number of dangers associated with faulty septic systems and the incomplete treatment of wastewater.  When a septic system is failing bacteria, nutrients and toxins pass through the system and reach ground and surface water.  This can be harmful to both the environment and you.

One of the biggest concerns is bacterial contamination of drinking water.  Often, only a small account of contaminated water can be extremely harmful.  Bacteria such as E. coli and Fecal Streptococci are present in human waste.  When ingested (through drinking water or when swimming), these bacteria can cause serious health problems and some strains are even fatal (i.e. Walkerton).

Nutrients like phosphorus that leach from a failing system are also of concern.  Nutrients get into the septic system through detergents and cleaners used in the house as well as through regular waste.  If the nutrients are not properly absorbed by the septic system soils, they can reach our surface water.  Once this happens, a whole host of lake wide problems can ensue.  Added nutrients like phosphorus can cause plant growth and algae blooms to occur.  This overgrowth can make swimming and boating difficult.  In addition, this overgrowth can eventually lead to the depletion of the dissolved oxygen supply in the water.  Depleted oxygen levels can disrupt the natural ecosystem balance, killing fish species and other aquatic organisms.


Alternative Wastewater Treatment Technologies

Conventional septic systems don’t always meet everyone’s needs.  Some sites are too small or otherwise unsuitable for a ‘regular’ septic system.  You might want to take some stress off your old leaching bed, or significantly increase the use of a smaller bed.  Fortunately, there are alternatives to septic systems.

These alternatives give you more options when building or retrofitting – composting toilets remove human waste from the wastewater equation entirely, while advanced treatment systems process wastewater very thoroughly making it much easier to dispose of.  Some of the cases where you should consider alternative systems are:

  • Cottages that are being converted to full-time residences
  • Old or abused leaching beds with a  heavy biomat
  • Homes or cottages that are close to lakes and rivers
  • Areas where there is shallow bedrock or a high groundwater table
  • Areas where there are clay soils
  • Heavily sloped sites


Composting Toilets

Composting toilets work by breaking down organisms that can be dangerous to human health (known as pathogens) and to eliminate human waste, into a stable soil material that is not unlike the soil found in outdoor composters.  These toilets look good, don’t smell, and require very little maintenance.  Depending on the capacity of the toilet, they can cost between $1000 and $3000.

There are several different types of composting toilets. For more information you should contact the Centre for Sustainable Watersheds to determine what type is right for you.


Sanitary Sewage Systems (Privies/ Outhouses)

Outhouses are generally used by individuals that are in a remote area such as a seasonal cottage, or for temporary purposes such as construction sites and are regulated by the Ontario Building Code.


Sanitary Sewage Systems (Greywater)

Greywater is waste water that does not include human waste and comes from sources such as dishwater, laundry tubs, washing machines and the bathtub. The Ontario Building Code states that Class 2 greywater systems are permitted to be installed when the amount of the water being released into the soil does not exceed 1000 litres/day or installation is permitting in an area that does not have pressurized water, but you should contact your local Health Unit to obtain the proper approval.


The table below lists the minimum horizontal clearance distances (in metres) for Class 1, 2, and 3 systems.

  From a wellWith watertightcasing to a depth of ≥ 6m From a spring used as a source of potable water, or well other than a watertight casing to a depth ≥ 6 m From a lake, river, pond, stream, reservoir, or spring not used as a source of potable water From a property line
Earth pit privy





Vault privy, pail privy





Greywater system











Advanced Treatment Systems

Typically, a traditional septic tank treats raw sewage only partially and produces a primary quality effluent.  An advanced treatment unit will treat wastewater to a higher ‘grade’ than this.  Systems may be added on to an existing septic tank, or may replace the tank completely.  The unit will still be hooked up to a leaching bed of some kind, but because the effluent is cleaner the stress on the leaching bed is carrying a lighter sediment load, it can legally be much smaller than a standard system would require.

Most advanced treatment units are classed as ‘Secondary’ or ‘Tertiary’.  This can mean one of two things: the treatment units might be:

  1. Additional units hooked up to a septic tank (a second and third unit), or
  2. A single unit that produces effluent of comparable quality to additional systems. Typically, secondary effluent is 4 to 5 times cleaner than primary effluent, and tertiary effluent is approximately 10 times cleaner.  The Ontario Building Code specifies which treatment systems are acceptable secondary and tertiary systems.

Advanced treatment units can be separated into two distinct treatment methods: suspended growth and fixed growth.  In suspended growth treatment, air is mixed with the sewage and bacteria so aerobic digestion (with oxygen) can occur.  In fixed growth treatment, the sewage is trickled over or through a medium (like foam cubes or peat).  The bacteria attach themselves to this substance and break down the effluent as it passes over them.

Both treatment types depend on aerobic bacteria to break down the waste.  Aerobic bacteria break down waste faster than the anaerobic (without oxygen) types in a conventional septic system.  This results in a much faster ‘turn around time’ in the system.  Aerobic bacteria produce fewer odours as well.


ECOCYCLET (Evapotranspiration Bed)

In addition to the use of secondary or tertiary treatment technologies, some groups are rethinking the way we treat our waste entirely.  For instance, a small group of organizations (including the Centre for Sustainable Watersheds) have been researching the use of water gardens to treat wastewater.

 ECOCYCLET is a patented bio-engineered system that uses plants for wastewater treatment from residential and small commercial sites.  In this system, the effluent from septic tanks is passed into an enclosed bed where microorganisms convert the wastewater into nutrients for plant growth.  High-transpiration plants are chosen to maximize the ability of the system to remove the water.  Water is also lost through evaporation from the soil.  A greenhouse or solarium allows year-round treatment.

ECOCYCLET is innovative in that it has zero discharge.  This means that no nutrients or pathogens are released into the environment.  The system is fully lined, and designed for plants to consume the entire load of wastewater.  Water that is not removed by evapotranspiration is fed back to a pumpable holding tank for recirculation.  This system represents a worry-free system, one that protects our lakes from the nutrient loading attributed to septic systems.

For information on specific types of alternative treatment systems, check the Ontario Building Code website



Design, construction, operation, and maintenance of septic systems are regulated by the Ontario Building Code (O.B.C.).  This regulation involves issuance of building permits for septic systems.  The O.B.C. is enforced under municipalities. Below is a list of the different classes that are applied to the types of septic systems.

Classes of Sewage Systems

The Ontario Building Code designates five classes of sanitary sewage of Sewage disposal.


Class 1: A chemical toilet, an incineration toilet, a recirculation toilet, a self-contained

portable toilet, and all forms of privy including a portable privy, an earth pit privy, a

pail privy, a vault privy, and a composting toilet system, all of which can receive

only human waste.

Class 2: A greywater system, which can receive only greywater waste

Class 3: A cesspool, which can receive waste only from a Class 1 System

Class 4: A leaching bed system, which can accept both human body waste and greywater


Class 5 A sanitary sewage system with an on-site holding tank for sanitary sewage produced

on-site, prior to removal by a haulage service provider; it can accept both human

body waste and greywater .


Building Permit Required

A building permit must be obtained from the Health Unit before any installation, extension, or

alteration of a sanitary sewage system can take place. Permit applications are typically associated with:

  • new construction on a vacant lot
  • alteration or additions to an existing building
  • construction of a new system for an existing building
  • corrective work or repairs to an existing system
  • upgrade of an existing system

The Health Unit provides a permit application package to the property owner. A typical application package contains an information package with sewage system worksheets, a property description and applicant information sheet, a site description, calculations and intended system type sheet, a site plan and applicant or agent signature sheet, a completion notice and a sewage system fee schedule. For information on contacting theLeedsand Grenville District Health Unit see Appendix


Capacity and Locations of Septic Systems

Because of the hazardous contents of wastewater, there are regulations that govern the components of septic systems, their installation, and their location on the site.  The legislation that governs septic systems is the Ontario Building Code.  For further information you should contact your local municipality for permitting information. Refer to the contact list for information on how to contact you local municipality.


Septic System Location

The Ontario Building Code also sets out minimum distance requirements for the installation of a system.  Most new septic systems on new building lots are now required to be installed 30m from open water (such as a lake or river).  They must be a minimum of 15m from your drilled well and 30m from a dug well.  They must also be at least 5m away from a swimming pool or vegetable garden.


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