What are the water main and the main sewer of a building?

The water main is the pipe that carries the drinking water from the municipal aqueduct to a residence. Once inside the building, the water main is provided with a valve: the main shut-off valve. It is the valve that closes the water to the entire building. The common materials that make up the water main are copper, lead, steel and plastic. The most common diameters are ½ “, ¾” and 1 “.

The main sewer is the pipe that drains sewage from the building to the municipal sewer. The sewer entrance, despite its name, is actually a sewer outlet. Inside the building, access to the sewer is provided by a cleanout: the main cleanout. It is the cap in the floor, close to the water main shut-off valve, which when unscrewed permits cleaning the sewer main in the direction of the street. The common materials that make up the main sewer are concrete, terracotta, asbestos-bitumen and plastic. The most common diameters are 5 “and 6”.

Some municipalities offer a third service (third pipe): the storm sewer (not shown in above illustration). This third pipe is specific to the collection and routing of rainwater coming from the French drain, the sump pump and the roof drain. The material used is plastic and the diameter is 6 “.

Replacement of the water main and the main sewer is a job that requires handling of heavy equipment, specialized underground plumbing knowledge and an understanding of municipal requirements. For these reasons, it is recommended to hire a competent plumbing contractor who is accustomed to underground plumbing.

Frequent causes of damage to water main and main sewer?

Roots in pipe:

Roots have seeped into the sewer through the joints. The sewer pipe is blocked. Often encountered with clay and concrete sewer pipes.

Crushed pipe:

The sewer pipe is crushed by the weight of the soil above it. The pipe is narrowed at one point, causing the blockage. Often encountered with asbestos-bitumen sewer pipes (No-Corrod).

Offset pipes:

A pipe segment has collapsed (offset down) with respect to the next segment. Often encountered with clay sewer pipes.

Perforated pipe:

A portion of the pipe broke and fell into the pipe. The broken piece causes a blockage in the pipe. Often encountered with concrete sewer pipes.

Advantages of entrusting the replacement and repair of your sewer entrance and your water inlet (water cut) to CHRONOS:

 25 year warranty

  •  We guarantee our work 25 years in writing. Our guarantee is transferable when the property is sold.

 Full service

  •  Our service is complete: protection of the floors where the workers circulate, replacement of the main sewer, replacement of the water main, jobsite cleaning.

Up to code

  •  Our installations are carried out in accordance with the National Building Code (NBC) and specific municipal regulations.

 Liability insurance

  •  We are a member of the Maîtres Mécaniciens en Tuyauterie du Québec (CMMTQ) and the Régie du Bâtiment du Québec (RBQ). Our liability insurance is $ 1,000,000.

After sales service

  •  We do a follow-up one week after the work is done to make sure everything is working normally and to answer your questions.

When should the water main and the main sewer be replaced?

 The water main is replaced:

  •  When the water main is perforated and leaking. There is loss of pressure and a possible caving of the ground above the leak.
  • When the diameter of the water main is decreased by corrosion or scaling.
  • When the water main is lead and lead is present in the drinking water.


 The sewer main is replaced:

  •  When the sewer main is damaged and can not be unblocked.
  • When a new French drain is installed. In some municipalities, such as St-Lambert and Boucherville on the south shore of Montreal, it is required to replace the sanitary sewer and to install a new storm sewer when replacing the building’s French drain.
  • When the main sewer has reached its useful life. Even when the main sewer is properly installed, it deteriorates due to the continuous vibration of the soil and the continuous effect of the weight of the earth above it which slowly crushes the pipes. Defective joints allow sand and soil to enter and, if a root is present nearby, it may also enter the sewer.

What are the signs that there is a problem with the water main and the main sewer?

  •  Water pressure drop, especially in the second-floor shower (water main).
  • Persistent rust in drinking water despite an internal distribution system free of galvanized steel pipe (water main).
  • Simultaneous emptying of the bath, washing machine and sink takes place more slowly than before (main sewer).
  • Toilets are regularly blocked (main sewer).
  • A rotten egg odor comes from the underground floor drain (main sewer).
  • Wastewater overflow through the garage floor drain or underground floor drain (main sewer).

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