Can you sell a house without a backwater valve in Montreal?

Can you sell a Montreal house that has no backwater valve?

Yes. No sentence cited on this page forbids the sale because the house has no backwater valve, because you cannot find one, or because you do not know whether one was maintained. What the sale does not skip is saying what you know. The office consolidation of the By-law concerning the protection of buildings against sewer back-up, 11-010, is updated to September 29, 2014, and says it was prepared for convenience only and has no official value. The sentences below are that text. A notary, or the City, reads the official by-law and each amendment (By-law 11-010, office consolidation of September 29, 2014).

City council enacted the by-law at its meeting of June 20, 2011. The English text says the public notice was posted at city hall and published in The Gazette on June 27, 2011. Article 2 says the by-law comes into force for each borough at the date shown in schedule A. No sentence in article 2 says a deed waits for a valve, or for June 27, 2011 (By-law 11-010, English text).

Which boroughs does by-law 11-010 name, and which buildings does it cover?

Article 1 says the provisions apply to the territory of the boroughs shown in schedule A. Article 3 says the executive committee may, by ordinance, amend that list and the date of coming into force on each borough territory. Article 4 says the by-law applies to a new building, to a building where transformation work on a plumbing installation is being carried out, and to a building having undergone a sewer back-up or flood. Article 9 says the provisions prevail over any by-law or code pertaining to the same objects. Article 6 says “Chapter III of the QCC” means the Quebec Construction Code, chapter III, Plumbing, the National Plumbing Code – Canada 2005 as amended by Order in Council 294-2008 of March 19, 2008. This page does not restate a sentence of that code that 11-010 does not print (articles 1, 3, 4, 6 and 9).

Schedule A of that consolidation names eighteen boroughs. It does not name Le Plateau-Mont-Royal. It does not name a linked city. This page does not state the rule of a linked city. The consolidation’s note says it contains Ordinance 1, adopted by the executive committee on April 2, 2014, adding Rivière-des-Prairies–Pointe-aux-Trembles, and Ordinance 2, adopted on September 24, 2014, adding Le Sud-Ouest. The original English by-law’s schedule, read beside that note, does not yet name those two boroughs. The dates in the table are the consolidation’s schedule A, not the adoption dates of the ordinances, and not June 27, 2011.

The City’s French page, updated 15 July 2025, says that if you have already been flooded or have had a sewer backup, valves on each plumbing fixture are essential, and above all mandatory under the municipal by-law, and that since 2011 valves must be installed in all new buildings in Montréal. “All new buildings” and “since 2011” are that page’s words. Article 4 is three cases, article 1 is schedule A, and schedule A does not give every named borough the same date. This page does not merge them. This page does not ask anyone to install a valve (Clapet antiretour : la clé pour prévenir refoulement d’égout et inondation, updated 15 July 2025, page in French).

Where does the text say a backwater valve is installed?

Article 29 replaces sentence (3) of article 2.4.6.4. It says that, subject to sentence (5), a backwater valve shall be installed on every drainage pipe that is connected to a building drain that serves a sanitary appliance located beneath the adjacent street. Article 31 replaces sentence (5). The English consolidation writes: “Where several sanitary appliances connected to the same drainage connection, the backwater valve may be installed on the drainage connection.” The French consolidation writes that, where several sanitary appliances are connected to the same drainage branch, the valve may be installed on that branch. “May” is not “shall.” Article 30 says a backwater valve shall be installed downstream from the trap seal of a floor drain. The French text writes “en aval du siphon d’un avaloir de sol.” “Trap seal” and “siphon” are the two texts. This page does not merge them (articles 29, 30 and 31).

Article 22 adds sentences to article 2.4.3.7. Sentence (12) says any retention pit receiving only storm water and subsoil water, and located beneath the level of the adjacent street, shall be equipped with an automatic pumping mechanism. Sentence (13) says the drainage piping of that mechanism includes a horizontal section installed above the level of the adjacent street and equipped with a backwater valve and a shut-off valve, in that order, downstream. Article 20 of 11-010, a different article, says a retention pit shall be located inside the building and shall not be exposed to frost. No sentence in articles 20 or 22 says the deed waits for a pit or a valve (articles 20 and 22).

The City’s page of 15 July 2025 says a valve is installed on the drain of each plumbing fixture, or of a group of fixtures, in the basement, and it names a toilet, a sink, a shower, a washing machine, and a floor drain in the garage. “In the basement” and “or of a group” are that page’s words. Article 29 is a sanitary appliance beneath the adjacent street, and article 31 is the “may” for several appliances on one branch. The page also gives a minimum size for a retention pit, 600 by 450 by 450 mm, or 24 by 18 by 18 inches. Article 20 of 11-010 does not write those figures. The City’s heavy-rain page, updated 23 June 2026, uses “clapets anti-refoulement,” not “backwater valve,” and says to check the presence and the working order of those valves on plumbing fixtures located below street level. It says a valve is indispensable for every floor drain or for the plumbing fixtures, and its examples are a toilet and faucets. “Indispensable” and “or” are that page’s words. They are not article 29. This page does not ask anyone to check or install a valve (heavy rain, updated 23 June 2026, page in French).

What does the text say about maintenance, access, and a permit?

Article 36 says the owner shall maintain appliances and equipment covered by this by-law in good operating condition by carrying out the necessary maintenance. Article 37 says the owner may not render inoperative, in whole or in part, any appliance or equipment covered by this by-law. “Covered by this by-law” is the limit of those two articles. They do not write “accessible,” and they do not write a number of times a year (articles 36 and 37).

The administrative codification of the By-law concerning the construction and conversion of buildings, 11-018, dated 2 September 2025, says it was prepared only for the reader’s convenience and has no official value. Article 74 of that codification records an amendment to the By-law concerning building maintenance, 07-034, adding article 16.2: the owner of a building must maintain every backwater valve and keep it in good working order. The codification writes “tout clapet anti-retour.” Article 36 of 11-010 writes the equipment covered by 11-010. This page does not merge them, and it has not read a separate consolidation of 07-034. Article 20 of the same 11-018 codification is a different trigger. It applies when borough rules require immunization measures for a construction authorized in a flood-risk zone, and it says the drainage drains must be equipped with backwater valves, and that the discharge pipe of the automatic lift pump must be connected above the level of the low-current zone and be equipped with a backwater valve. That article is not article 29 of 11-010. The flood-zone page already cited is the sale in a mapped zone (codification of by-law 11-018, 2 September 2025, articles 20 and 74, page in French).

The City’s page of 15 July 2025 says to plan easy access so the valves can be maintained, and that ideally, twice a year, you check that the valve works and is not obstructed. It says valves are sometimes installed in the wrong place or too worn to work, that rats can gnaw them, and that for some people the location and the condition cannot be known because a floor has blocked the access. Those sentences are the page’s. They are not articles 36 and 37. Article 14 says that, where application of the by-law is delegated, the executive committee or the borough council may require, by ordinance, that an owner obtain a permit before the work covered by the by-law is carried out. Article 15 says that, where a permit is required, no person may without a permit install the appliances or equipment under the by-law, add sanitary appliances at a level beneath the adjacent street, or alter an existing plumbing installation under the by-law. “May require” and “where a permit is required” are article 14 and article 15. The Île-Bizard–Sainte-Geneviève permit page, updated 25 June 2026, says that since August 13, 2001, conformity of plumbing work inside buildings is no longer a matter for the urban-planning division but for the Régie du bâtiment du Québec, that plumbing work on the building’s network can be carried out without prior authorization from that division, and that the work must still comply with the applicable statutes and by-laws. It then names 11-010 for a new building, for a building where transformation work on a plumbing installation is carried out, and for a building that has had a sewer backup or a flood. That page is one borough’s. This page does not pick it as the rule for the Island, and it does not ask anyone to install, check or maintain a valve, or to apply for a permit (Île-Bizard–Sainte-Geneviève permits, updated 25 June 2026, page in French).

What does the seller’s form ask about a valve, a backup, and a flood?

On the French PDF read for this page, marked DV 00001 and V24, copyright 2012 and 2022, the answers are to your knowledge and in good faith. The form says it must be used when a brokerage contract for the sale of an immovable is made with a private individual, for a chiefly residential immovable of fewer than 5 dwellings, excluding divided co-ownership. On a sale that is not made under that contract, you still say what you know, in writing. How that sale runs is How do you sell a house without a real estate broker in Quebec?. The English PDF, read for the English wording, shows V17 in the margin. This page does not call the two files one edition (Déclarations du vendeur sur l’immeuble, form DV, page in French).

The items below follow the French V24 wording. D9.13 asks whether the immovable is equipped with a backwater valve, in parentheses to prevent backups of sewer water and rainwater, and the boxes are “do not know,” yes, and no. D9.1 asks whether there have been plumbing problems and, if yes, which ones. Backup is one of the boxes, beside a leak, a large change in pressure or flow, a frozen pipe, rust in the water, an odour, poor drainage, an abnormal noise, or other. D9.2 asks whether there is a sump or a water-retention pit. D9.3 asks whether there is a pump. D9.12 asks whether there have been problems with wastewater drainage and, if yes, names an odour, an overflow, or other. D14.1 asks whether, in addition to what is already mentioned, the immovable has sustained damage from an ice storm, a wind storm, a flood, a fire, or another event. D15 is the clause number, the place, the year, and how the situation was dealt with, if it was. What you can say, if you know it, is whether a valve is there, where it sits, whether you can reach it, whether it has been maintained, and any backup or flood you know about, or that you do not know. D9.4 asks, if there is a French drain, whether a system lets you reach it to inspect and clean it. That question is the French drain. It is not D9.13. D4.1 asks whether there has been water infiltration, and where. That is a different page (Can you sell a house with water infiltration or a leaking roof in Quebec?). D14.5 asks whether, in addition to what is already mentioned, anything else could affect the value, the income, the expenses or the use. The form asks that question. This page does not answer it with a figure, and it does not say that a missing valve raises or lowers a price.

Can you sell with the house as it is, and without the legal warranty?

Two paths are not the same promise. You can sell with the house as it is, and say what you know, on the form when that form is used and in writing when it is not. Selling without the legal warranty is a clause in the promise and the deed. It does not cover a problem you knew and did not disclose. Article 29’s “shall,” inside the buildings and the boroughs article 4 and schedule A name, and article 36’s maintenance of the equipment the by-law covers, are the by-law’s. No page cited here says the deed, or the choice of buyer, erases them.

Article 1726 is the warranty of quality, in the text now in force. The seller is bound to warrant the buyer that the property and its accessories are, at the time of the sale, free of latent defects which render it unfit for the use for which it was intended or which so diminish its usefulness that the buyer would not have bought it or paid so high a price if he had been aware of them. The seller is not bound, however, to warrant against any latent defect known to the buyer or any apparent defect. An apparent defect is a defect that can be perceived by a prudent and diligent buyer without the need to resort to an expert (Civil Code of Québec, article 1726). This page does not decide that the absence of a backwater valve, or a valve you cannot reach, is a latent defect. Article 1728, in the text in force since 1 May 2014, says that if the seller was aware or could not have been unaware of the latent defect, he is bound not only to restore the price, but also to make reparation for the injury suffered by the buyer (article 1728).

Article 1732, in the text in force since 6 April 2016, says the parties may, in their contract, add to the obligations of legal warranty, diminish its effects or exclude it altogether but in no case may the seller exempt himself from liability for his personal acts or omissions (article 1732). Article 1733 says a seller may not exclude or limit his liability unless he has disclosed the defects of which he was aware or could not have been unaware and which affect the right of ownership or the quality of the property. An exception may be made to this rule where a buyer buys property at his own risk from a seller who is not a professional seller (article 1733). The exception is not a permission to stay silent. Éducaloi says that, if the warranty is excluded, you cannot sue for a hidden defect, and the remaining path is to show that the truth was voluntarily hidden on a point so important that you would not have bought, or in any event not at the same price. Éducaloi also says the legal warranty cannot be invoked for a problem that was declared in the seller’s declaration (Immobilier : acheter sans garantie légale, page in French). The OACIQ says the legal warranty waiver will not protect the seller against legal action for defects of which he was aware and which he should have disclosed (The legal warranty of ownership and quality). How the clause is written is the as-is page already cited. A notary or a lawyer reads the clause. This page does not.

A direct sale is a further path. Bruce Malcolm buys houses himself on the Island of Montreal and the surrounding areas. He holds no broker, agent or appraiser licence, and he is not an advisor. There is no inspection and no commission. An offer with no inspection condition does not, by itself, set aside the legal warranty of quality. You say what you know about the valve when you send the address: whether one is there, where it sits if you know it, whether you can reach it, whether it has been maintained, and any backup or flood you know about, or that you do not know. He does not install a valve, he does not open the plumbing, and he does not apply for a permit. The closing date is one you choose once the notary can sign. Sending the address starts a conversation (request an offer). The form does not commit you. A notary or a lawyer reads the deed.