Septic systems

A conventional septic system is composed of a septic tank and a leaching bed. A septic system treats your sewage right in your own yard and releases the treated effluent back into the groundwater.


The septic tank retains the solid portion of household wastewater and begins its decomposition. Heavier solids settle out of the wastewater and accumulate on the bottom of the septic tank as sludge. Lighter solids float to the surface and accumulate as scum.





The Leaching Bed

Liquid wastewater leaving the septic tank is directed towards the leaching bed. Wastewater is filtered through the ground and treated naturally by the decomposing action of bacteria and micro-organisms living underground.


The Septic Tank Pump-Out

Over time, the sludge will build up in the bottom of the septic tank. If the sludge is allowed to accumulate it will eventually flow into the leaching bed and rapidly clog the distribution pipes. Once the pipes become clogged, the wastewater will either seep to the surface of the ground or worse yet, back up into your house. Not only can a clogged septic system be hazardous to the environment and to your family’s health, it also represents a very expensive repair bill.


Effluent Filters

An effluent filter can be installed into a polyethylene outlet baffle; this will add a protection to the leaching bed. The effluent filter captures the fine particles carried by wastewater.

However, if your septic tank has one, it must be cleaned once or twice every year to prevent clogging. Simply remove the filter and rinse it with a garden hose over the solid side of your septic tank.

Please note that, since January 2009 in the province of Québec, every prefabricated septic tanks must comply with BNQ (Bureau de Normalisation du Québec) standard 3680-905, and be equipped with an effluent filter at the outlet. 


The Municipality of Chelsea, as part of its septic tank emptying program, empties and inspects all the residential septic tanks on its territory once every two years.

When you receive a notice at your door mentioning the week your septic tank will be pumped out, you must prepare the septic tank and if the lids are buried, you must uncover the two original septic tank lids and sewage pump, if applicable. 

Please note that if your septic system consists of a grey water tank and a holding tank, both will be emptied. We will not pump septic tanks with extension pipes.

A municipal employee will accompany the contractor when inspecting your system and will hand you an inspection report.


Download the 2019 itinerary


For more information on the septic tank emptying program, please contact the Public Works Department at 819-827-1160.


You must apply for a permit before any work can begin for the installation of a septic tank on the territory of the Municipality of Chelsea. This is required for the construction of a complete septic system and for any partial work such as the installation of a holding tank, replacement of a septic tank and corrective measures for an existing leaching field.

Your application must include the permit application form for a septic system and two copies of an expert report (engineer or qualified technologist who is a member of a recognized professional order in Quebec).


  • For use with a discharge of less than 3,240 litres per day.


Prix du permis

  • $250: new installation
  • $100: correction or modification
  • $100: septic tank replacement

Refundable deposit: 

  • $300 for tank replacement
  • $500 for a new system or modification of an existing system

Demande de permis


Distances must comply with the Ministère de l’Environnement’s Q-2, r.22 Regulation respecting waste water disposal system for isolated dwellings and Environment Quality Act


If you are looking to obtain : 


You must complete the application form, Request for Information on a Septic Installation and drop it off at the Municipality’s reception desk along with a payment of $50 payable by check, debit or cash.  The owner's signature is required except in cases where a notary was commissioned and making the request.  In this case, the notary’s office will be charged.  The letter sets out information available on file about your septic system and the results of the last inspection made under the Septic Tank Emptying Program offered by the Municipality.  It should be noted that the inspection carried out under this Program is a visual inspection only.

We understand that these types of letters are required rapidly in real estate transactions, nevertheless, please allow 10 business days for the issuance of this document.


We recommend you have it inspected by a consultant specialized in sanitary engineering.  We would like to point out that the Municipality of Chelsea cannot guarantee the compliance, longevity and proper functioning of the septic system.  

We ask that you send your request by email.  A delay of approximately 10 business days should be expected to process the request.


In Chelsea, various types of septic systems may be installed on the territory depending on the topography, land dimensions and soil composition.

Sometimes, conventional systems and advanced secondary systems cannot be installed because:

  • the soil composition is high in clay
  • there is rock near the surface
  • underground water sources are not very deep
  • the slope is too steep
  • the land surface is restricted, as ascertained by a technologist. 

In such a case, the Ministère de l’environnement et de la lutte contre les changements climatiques du Québec (MELCC) allows systems with a tertiary treatment. The most common tertiary system is the treatment procedure with an Ecoflo® Biofilter and an FDi disinfection filter. Some systems with the Roseau épurateur also fall into this category.



Click on the image for an example of a septic system with tertiary treatment and release into the environment.


In Chelsea, strict environmental monitoring of septic systems with tertiary treatments that release waste water into the environment is ensured by the municipality to comply with prevailing regulations. These regulations set out the sampling calendar, pricing and environmental standards that must be respected.

Sampling and analysis fees may be integrated with the property taxes on a building. The municipality ensures compliance with the provincial Q-2, r. 22 Regulation respecting waste water disposal systems for isolated dwellings where environmental standards are out of line and initiates procedures with residents, if required (stopping use, repairs, etc.).

A third-party company is commissioned by the municipality to sample the effluent from these systems according to a sampling calendar established in By-law No. 768-10 (link) and the provincial compliance level for fecal coliforms is 200 UFC/100 ml at the point of sampling.


In case the level exceeds the provincial standard:

The level is over the limit if the concentration in two samples taken within a 60-day period exceed the provincial standard (fecal coliforms: 200 UFC/100 ml).

If the discharge standards are exceeded, the owner must temporarily seal the septic tank and seek the advice of his or her consultant to correct the system within the time frame established by the officer in charge.

In addition, when the discharge standards are exceeded, the sampling calendar will be downgraded to year 1.


For questions regarding this type of septic system, please contact the Sustainable Development Advisor at

Planning and Sustainable Development Department