Septic systems in Greater Montréal

Septic systems: what to know here

Greater Montréal holds 23% of the licensed companies in this trade in Quebec: 867 of 3,739, going by the active licences as of November 3, 2026. Of our 15 trades, this one comes 8.

In parts of Greater Montréal without municipal sewers, mostly on the outer shores, a house has its own septic system: a tank and a treatment field. Building one follows the Regulation respecting waste water disposal systems for isolated dwellings and needs a permit from the municipality, based on a site characterization study.

By sector and by area

By sector there are the Island of Montréal 234, Laval 132, the South Shore 269 and the North Shore 232. In Montréal, Rivière-des-Prairies–Pointe-aux-Trembles comes first (52), then West Island (35), Ville-Marie (Downtown) (22), Saint-Laurent (22) and Saint-Léonard (21). The other towns with the most: Laval (132), Mirabel (62), Terrebonne (46), Longueuil (33), Carignan (19), Blainville (17), Boucherville (17) and L'Assomption (17).

Of the 234 island companies in this trade, 165 have 10 years of licence or more — the first dates from 1984 — and 2 have been licensed for under three months. Other frequent trades among them: wells (215), renovation (154) and heating and cooling (122). You can call 233 directly; 226 have a 514 or 438 number.

Before you ask for quotes

Installing a septic tank or leaching field falls under subcategory 2.4. A municipal permit is required before the work, based on a site study by a professional.

Give the number of bedrooms, the type of soil if you know it, the year of the current system and your municipality’s pumping schedule. Ask who prepares the site study and who files the permit application.

Subcategories on these companies’ licences: 2.4 On-site wastewater (septic) systems.

See also

• How it works
• RBQ licence check: how to verify a Quebec contractor
• Septic tank pumping: how often and what to check