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Everything You Need to Know About Septic Tanks

Everything You Need to Know About Septic Tanks

Exterior renovationsEverything You Need to Know About Septic Tanks

For any property that's not connected to a municipal sewer system, putting in a septic system is a must. To demystify its functioning, on top of the recommended damage protection methods, we bring you the following article.

Septic Tank: How Does it Work?

Soumission_Rénovation "fosse septique"

Source: Canva

First, wastewater flows to the septic tank, which is a tank buried beneath ground level, in which water is stored. It has two separate compartments which make it possible to separate liquids from solid matter. Note that septic tanks are made of concrete, fibreglass or polyethylene. Their size can vary between 2,300 and 5,500 litres. Although it was once possible to make them out of metal, this hasn't been the case since 1980.

At this stage, bacteria contained in the tank make digesting organic matters possible by liquefying the solids, settling and eliminating any impurities found. Liquids pass through the liquid compartment and then flow into the purifier (also known as an "absorption bed" or "leaching bed") through a distribution facility or pipe. Residual solids and grease remain in the septic tank.

The leaching bed consists of a network of perforated pipes laid in a layer of gravel that releases the wastewater into the added soil. The microorganisms found in the leaching bed contribute to the process of biodegradation. A leaching bed's key role is to eliminate suspended matter and microbes that remain in the water.

To ensure optimal wastewater sanitation, the water undergoes a second and third treatment by the purification element.

What's the Price of a Standard Septic Tank?

Soumission_Rénovation "fosse septique de grande taille"

Source: Canva

Installing a septic system (septic tank and leaching bed) costs between $10,000 and $60,000, depending on the technology used during its construction.

Also, let's not forget the cost associated with the soil analysis test, which varies from one region to another, but is between $600 and $2000.

Factors that Influence the Price of Septic Tanks

To answer this very legitimate question, it should be noted that many factors will influence the total cost. Among these, let us note:

  • Type of septic system (bioreactor or biofilter);

  • Size of system installed (depending on the water flow to be treated);

  • Type of equipment used to install the system;

  • Materials used during the course of the project and their availability;

  • Site accessibility;

  • Amount of rooms in the home.

Want more details about the cost of a septic tank? Check out our article What Is the Price of a Septic Tank?

Septic Tanks: Quebec Regulations

It wasn’t until 1981 that the Government of Quebec decided to establish a regulation regarding wastewater disposal for isolated dwellings, which was revised in 2011. Said regulation was designed to establish strict measures when it comes to the construction, installation, and sale of septic tanks. In fact, this regulation clearly states that all companies that sell this type of system in Quebec must be certified according to the NQ 3680-910 standard.

Furthermore, let it be said that prior to replacing and installing a new septic tank, a soil test must be performed as well as establishing a construction quote and site plan to ensure that it meets the existing regulations. Otherwise, obtaining the required permits to undertake such a project won’t be possible. 

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Ensuring Septic Tank Is Functioning Properly

Soumission_Rénovation "fonctionnement d'une fosse septique"

Source: Canva

Several steps should be taken to ensure a properly functioning septic tank:

  • Have your septic tank emptied by a professional every 2 years (for year-round use) or every 4 years (for seasonal use);

  • Protect the leaching bed;

  • Control the amount of water discharged;

  • System maintenance.

What are the telltale signs of a full septic tank?

Several signs may allude to a problem with your septic tank, such as:

  • Foul odour seeping out of the ducts;

  • The appearance of black liquid on the ground;

  • Leaching bed covered in very green and spongy turf;

  • Particularly slow-draining water from the toilet, sink or shower;

  • An intermittent functioning pump, if your system has one;

  • Bacterial contamination inside the septic tank.

Emptying Your Septic Tank

When it comes to emptying your septic tank, note that it’s necessary to do so to prevent solids and fats from accumulating inside the tank and compromising the proper functioning of the leaching bed. 

After having it emptied, it’s important to leave a layer of mud on the bottom of the tank, as this helps contain a certain amount of bacteria inside. This has a very precise function, namely that of helping to reduce the quantity of sludge present in the tank and therefore, to reduce the amount of cleaning the tank requires.

When it comes to maintenance, a good indicator is to observe the amount of sludge present in the septic tank: If it reaches 30 centimetres or higher, your septic tank needs to be cleaned. Ideally, have your septic tank emptied during the summer. If you wait until later in the year, the bacterial flora won’t have enough time to rebuild before the cold weather sets in.

Protecting Your Septic System's Leaching Bed

To ensure that nothing could crush the pipes or compress the soil, avoid installing or building a terrace or patio atop a leaching bed. Damaging the pipes would be fatal to the proper functioning of the septic system, as the leaching bed can no longer function properly.

Controlling the Quantity of Water Discharged

Controlling the amount of water found in the tank has two main purposes: reducing water consumption and avoiding using a large amount of water over a short period of time. The first happens when there’s a lack of decomposition of organic matter, occurring when the water flow is too high inside the septic tank. To reduce the amount of water used, make good use of these tips:

  • Use your washer for regular-sized loads only;

  • Start your dishwasher only when it’s full;

  • Fix leaky faucets;

  • Avoid using the garbage disposal;

  • Install water-saving devices on plumbing fixtures;

  • Take fewer baths (it's better to take showers).

In regards to using too much water over a short period of time, it’s advised against since it keeps solid particles in suspension which are later transferred to the purifying element.

Also, make sure that the drains and gutters aren’t routed to the septic tank and the purifying element, as this will lead to too much water. Finally, note that the use of softeners isn't recommended since it results in excess water use and enhanced concentration of minerals.

Septic Tank Maintenance

entretien fosse septique

Source: Canva

As a first step, it’s important to maintain the interior of the tank using products specifically designed for this purpose. These are used to prevent the obstruction of pipes. Following this idea, it's also recommended to clean the pipes to loosen any residue stuck to the walls while eliminating scale, as this can be very damaging to the proper functioning of the septic tank.

Lastly, it’s recommended that you clean the filters of your septic tank as well as the pre-filter, these can be found on the liquid side of your tank. You can simply rinse them off using a garden hose. As the pre-filter is more difficult to remove, tie a string to its end to be able to lift it easily. We’d recommend taking on this cleaning process every fall.

What's the average lifespan of a septic tank?

As we previously pointed out, septic tank installation is a very expensive project. This is why anyone wishing to have this system installed should be curious about its longevity. To answer this question, their lifespan varies between 20 and 25 years.

In this regard, you should know that the lifespan of a septic system is very much dependent on the quality of its installation. Therefore, it’s essential to entrust this project to an experienced professional holding the licenses required to carry out the installation following industry standards.

What products are prohibited in the septic tank?

We recommend avoiding several products if you want to keep your septic tank in good condition. The first concerns those that could reduce bacterial activity such as disinfectants (bleach), motor oil, solvents, paints or other chemicals used to unclog plumbing as well as washing machine water that has traces of softeners.

Be aware that cleaning products, phosphate-based detergents and soap cause algae growth in rivers and surrounding water sources. Moreover, phosphate-based products are very damaging to marine life.

Lastly, we should mention that all elements that aren’t degradable, such as hair, oil, grease or tissues, must be avoided.

How do you detect a leak?

Note that it’s possible to perform a fluorescein test to be sure. Fluorescein is a dye that reacts to the presence of contaminants, whether they’re on the ground or in a surrounding waterway. After the test, wait a maximum of 48 hours and then you’ll know if there's an issue with the system's waterproofing or not.

How much does it cost to pump a septic tank?

To empty your septic tank, you’ll have to pay between $150 and $700 (for a three-bedroom residence).

If you need confirmation that the entire septic system that's in place does indeed comply with current regulations, inspections usually cost between $400 and $500.

Price Overview

Type of service


Soil test

Between $600 and $2000 (Varies according to region)

Septic system installation

Between $10,000 and $60,000

Installation inspection

Between $400 and $500

Emptying septic tank

Between $150 and $700

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Last modified 2024-04-19

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