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Date Posted: 2021-02-18

What is a Septic System and How Much Will it Cost?

The septic system usually consists of two main components: the septic tank and the absorption bed that is sometimes referred to as the disposal, leach or drain field. The septic system is connected to the house by sewage piping.

The price that you should expect to pay for the system and installation will vary widely depending on the size of the home, soil conditions and the type of system you require or decide to go with. However, most basic residential systems will range in price between $10,000 and $25,000 with more complex commercial or large residential systems ranging from $30,000 to $85,000. 

Typical replacement costs tend to be higher and depend on how much damage has been done to the soil and the specific site conditions that need to be restored after construction.

Factors Influencing the Price of Septic Systems in Ontario

In Ontario, the cost of a new septic system varies depending on several factors such as...

What Size Septic Tank Do You Need

All septic systems in Ontario must be constructed to adhere to the Ontario Building Code. The code regulates everything from the site design, construction, operation and maintenance of septic systems for single-family units. In most instances the Building Department of the local municipality will be in charge of certifying plans, issuing permits and doing the inspections required during the construction of the septic system.

A common misconception with regard to septic tanks is that the size of the system is determined simply by home size. While square footage can be a critical factor, bedroom count and fixture counts can also dictate the flow rate determination. Typically septic tank sizing will be two times the daily flow calculation.

How To Calculate Daily Flow Rate

The misconception is that the daily flow rate is calculated from the number of occupants or the number of bathrooms.

The Ontario Building Code assumes that every bedroom will have two people living in it. The estimation is that every person will be using at least 275 litres. As such, a house with two occupants will average 550 litres for every bedroom.

According to the Ontario Building Code, the Bedroom Rate is:

3 Bedroom home - 1600L (Minimum)

4 Bedroom home - 2000L

5 Bedroom home - 2500L

Anything larger than five bedrooms will add an additional 500L per bedroom.

Square footage can also add to the daily flow rate with a decreasing scale.

Apart from the bedroom count, the number of toilets, fixtures, sinks, bathrooms, etc in a home may result in a higher daily flow rate. If you have more than 20 fixture units then every additional unit will require the addition of 50 litres to the bedroom rate.

How Do Site Conditions Affect Septic Bed Design, Size and Costs

The Septic Field is an important and critical component of the Septic System design as a faulty one will result in the discharge of untreated sewage into underground water or streams. In the determination of the field design, the amount of time it takes for the effluent to be absorbed into the ground is very important.

If you are working with very sandy soils, it will typically take less than 10 minutes to have a drop of 1 cm or more in the effluent filled hole. Clay soils that usually have smaller particles and are less porous could take as much as 50 minutes or more to drop one centimetre.

Once the time to absorb water (Soil T Time) is determined, you will combine it with the Daily Flow number to get the minimum size requirement of the drainage field.

Given that there are a variety of septic systems, it is not possible to give one answer about how large the drainage field should be. However taking the most conventional gravity flow trench bed system in Ontario, the total length in metres of the trench system is found by multiplying the T time with the daily flow rate and dividing it by 200.

For instance, if we have a four-bedroom house on a sandy lot, the total trench length would be 2000 litres multiplied by 10 (time for absorption in sandy soils) divided by 200 (Q X T time) / 200. The approximate pipe length and excavation would be 100 metres of pipe length and excavation.

Gravity filter beds tend to cost the least to install and maintain where the materials are readily available. In most Ontario locales, you can get small filter beds installed for between $10,000 and $14,000. These systems are very basic and can work in lower T time soils although they may not have as long of a life cycle in higher T time soils.

If the T time is greater than 40min/cm, it will be more costly to install a regular stone and pipe trench system or filter bed and you may require a tertiary treatment system and raised bed. Raised beds usually require the importation of suitable septic sand and the costs will depend on how much will need to be imported. 

Typical tertiary treatment systems range from $30,000 to $55,000 with some larger homes or difficult sites requiring systems beyond 60, 70 or even $80,000.

How Much Do Septic Systems Cost By Tank Size

The septic tank you need varies depending on the flow rate of the home. Typically the septic tank size rule is 2 times the daily flow. So, if you have the 2000L per day flow rate discussed previously, this would require a minimum septic tank capacity of 4000L. Typically septic tanks are constructed of concrete, often the least expensive option as well as poly or less often fiberglass. 

How Much Does A 2 or 3 Bedroom Septic System Tank Cost

The average septic system for a two or three-bedroom home will need at least a 3600L tank on the lower end and a 5400L capacity septic tank on the higher end. Still, it will be critical to confirm with the Ontario Building Code regulations that outline the exceptions including the minimum size of the tank. The cost of a 3600L capacity concrete tank will typically cost between $1500 and $2500 before delivery and installation.

How Much Does A  4 Bedroom Septic System Tank Cost

The minimum septic tank capacity for a 4 bedroomed home is 4000L. How this is achieved may vary as the Ontario building code allows the septic tank to be built-in compartments. As such, one can still achieve the standard by having two or more tanks. The average cost for a septic tank of 4000L capacity ranges in price between $2000 and $3000.

How Much Does A  5 or 6 Bedroom Septic System Tank Cost

The septic system for a five or six-bedroom house will need at least a 5000L septic tank which can handle between 1500 and 2500L of wastewater every day. The cost to install the typical 5000L tank will range in price between $2500  and $3500 depending on the material used to build the tank.

How Much Do Different Types Of Septic Systems Cost

Our breakdown will consider the materials and costs that are typical with the construction, design and installation of traditional septic tank systems using gravity design.

Conventional or Anaerobic Septic System Cost

Conventional or anaerobic systems cost an average of $18,000 to install for most single-unit dwellings. with most installations costing between $14,000 and $22,000. Overall anaerobic systems are typically the cheapest, easiest and quickest systems to install.

Aerobic Septic System Cost

The cost to install an aerobic system will typically average between $25,000 and $35,000 to install. Aerobic septic systems use an oxygen rich environment or oxygen generated by a motor controlled by a timer to help break down solids. Since an aerobic system can disperse effluent to a smaller bed you can have more space on your lot for other things.

Mound Septic System Cost

The cost to install an above-ground mound septic system will be about $18,000 to $25,000. Due to the need to bring in additional soil and construct the septic system above ground the costs for this type of system might be two or three times what you would pay for a conventional system.

Sand Filter Septic System Cost

This type of septic system will set one back between $14,000 and $25,000 to install. It has several similarities with the conventional septic system. The big difference is that the effluent is distributed to the stone and pipe as well as filter sand media. 

Standard Septic System Costs Breakdown

Tank: Septic tanks can be made of a variety of materials that include polyethylene, fibreglass, and concrete. Concrete septic tank prices may range between $1000 to $6000 depending on the material and availability.

Gravel: The amount of gravel needed will depend on the overall landscape and the type of soil on the site. The average cost of clear stone in Ontario is $14.00 to $25.00 per ton. You should also add in trucking time per ton that is usually between $80 to $100 an hour or approximately $5 per ton for a 1 hour round trip.

Piping: The piping needed for septic systems will also vary depending on the design and size of the septic system. The typical price for 3-inch perforated pipe is about $500-$1000 per system.

Excavation: You will usually have to pay anything from $100 to $160 for every hour with most systems taking from 2 to 5 days to complete.

Additional Costs and Considerations

Aside from the usual costs, there are other considerations that have to do with things like the leach field, the cost of permits, grass restoration among other things.

If the leach field on the site has fencing, rocks or trees that need to be removed, or is hard to access, you will pay more to get these removed which can add up the installation cost.

You will also have to get grass or sod for your leach field and depending on where you are sourcing it, this could also result in high costs due to trucking or supplier constraints.

Regardless of the type of septic system you intend to install, you will have to pay for designs and permits which may run at a minimum of $1 500 in Ontario.

Since the installation of the septic system is a huge project, it may require the qualification of bids from several contractors. This will require the checking of references and determination that the contractor has insurance and has guarantees and warranties of quality work.

Many installers will also offer maintenance services that may or may not require extra payment. With such agreements, you will have your septic system inspected at set periods.

Septic System Maintenance Schedule: Pumping & Cleaning Costs

The replacement or repair of a septic system may cost anything from $500 on the lower end and up to $5000 for major repairs. However, once installed, septic systems that are well maintained may last anywhere from 15 to 40 years. This is because there are several aspects that impact the life expectancy of the system.

These aspects include anything from clogging by roots, flooding by ground or surface water, damage of the leach field by vehicle traffic or even chemicals used in the home or business.

How often should I have my septic system pumped?

The total effluent generated, the number of people in the household, the size of the tank and the amount of solids present will determine how often you need to pump the septic system. According to the Ontario Building Code, the septic tank must be pumped when sludge occupies ⅓ the total capacity of the tank. Pumping frequency is typically every three to five years with systems having pumps, mechanical components or electrical float switches requiring more regular inspection, repair, treatment and higher maintenance costs. Some contractors will do the maintenance of your septic system for free over an agreed period.

The frequency of pumping is also influenced by how many people reside in the home. The average three bedroomed home will follow the following timetable for septic tank pumping and treatment intervals:

1 Person: Every seven years

2 People: Every six years

3 People: Every five years

4 People: Every 3-4 years

5 People: Every two years

Who to Call Now

Allto Construction has been designing, installing, maintaining and repairing septic systems for over 50 years. Operating out of Orangeville Ontario we travel to Brampton, Georgetown, Guelph, Fergus, Elora, Mount Forest, Alliston, Newmarket and beyond. Whether you are in our typical range or not reach out if you have a question or are looking for a reputable contractor in your area. We are always happy to help.

Allto Construction Toll-Free 1-800-265-3348

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