Yes No Share to Facebook
Damage Arising From Toilet Overflow
Perceived Misuse Requires Proof of Probable Cause
Last Updated: August 22 2026
Question: In Ontario, who is responsible for damages and cleanup costs if a toilet overflows or there is a sewage backup in a rental unit?
Answer: In Ontario, a landlord is generally responsible for keeping the residential complex and rental unit in good repair and fit for habitation, and where a sewage backup or overflow starts, the landlord should investigate and arrange timely repairs, then may seek reimbursement from the tenant only if it can prove the tenant, an occupant, or a permitted guest wilfully or negligently caused the “undue damage” (see Residential Tenancies Act, 2006, S.O. 2006, c. 17). If you believe you caused the problem was tenant misuse, the key challenge is proving it is “more likely than not” the tenant’s conduct (not just possible), which the Landlord and Tenant Board discussed in S.M.O.F. v. D.C., 2016 CanLII 72064. For practical next steps and evidence-focused guidance on filing or defending an application, contact Vagans Legal at (416) 473-8472.
Add this website to Google Preferred Sources
Understanding Who Is Responsible for Damage From an Overflowing Toilet Requires Determination of the Cause
The consequences of an overflowing toilet, sewage backup, or other source of water damage, can be significantly costly and troublesome to clean up and repair; and accordingly, disputes between a landlord and a tenant regarding the cause of such damage, and the responsibility to pay for such damage, often occur.
The Law
Within the case of S.M.O.F. v. D.C., TET-71837-16 (Re), 2016 CanLII 72064, the Landlord Tenant Board provided a thorough explanation regarding the determination of responsibility for an overflowing toilet or sewage backup whereas, while referencing the Residential Tenancies Act, 2006, S.O. 2006, Chapter 17, it was said:
24. With respect to the sewage back up the Tenant’s application is based on the rights set out in sections 20 and 22. The relevant provisions read as follows:
20. (1) A landlord is responsible for providing and maintaining a residential complex, including the rental units in it, in a good state of repair and fit for habitation and for complying with health, safety, housing and maintenance standards.
22. A landlord shall not at any time during a tenant’s occupancy of a rental unit and before the day on which an order evicting the tenant is executed substantially interfere with the reasonable enjoyment of the rental unit or the residential complex in which it is located for all usual purposes by a tenant or members of his or her household.
25. The Landlord’s claim for compensation related to the sewage back up is based on sections 34 and 89(1) which say:
34. The tenant is responsible for the repair of undue damage to the rental unit or residential complex caused by the wilful or negligent conduct of the tenant, another occupant of the rental unit or a person permitted in the residential complex by the tenant.
89. (1) A landlord may apply to the Board for an order requiring a tenant to pay reasonable costs that the landlord has incurred or will incur for the repair of or, where repairing is not reasonable, the replacement of damaged property, if the tenant, another occupant of the rental unit or a person whom the tenant permits in the residential complex wilfully or negligently causes undue damage to the rental unit or the residential complex and the tenant is in possession of the rental unit.
26. The wording of subsection 20(1) indicates that as soon as the sewage backup problem started the Landlord was in breach of the Act. She had an obligation to investigate and repair in a timely fashion. Because of this obligation it is not prudent for a landlord to refuse to do repairs even if the landlord believes the tenant is responsible for the disrepair; rather, the provisions of the Act set out above should be read together. In the situation where the landlord believes the tenant is responsible for causing the disrepair, the landlord should do the repairs and then seek to recover the cost if he or she can establish the tenant, an occupant or a guest wilfully or negligently caused the damage.
As per the S.M.O.F. case shown above, the Residential Tenancies Act, 2006, imposes the responsibility for repairing and incurring the cost of damage arising from a maintenance issue upon the landlord. However, where a landlord believes a tenant, or a guest of a tenant caused damage, the landlord may commence a Landlord Tenant Board proceeding via an Application seeking an Order that the tenant reimburse the landlord for the cost of the repair work incurred by the landlord.
As a difficult challenge for the landlord who believes that the damage from water or sewage results from a misuse by the tenant or a guest of the tenant, the landlord bears the burden of proving that the cause was probably due to misuse by the tenant rather than just possibly due to misuse by the tenant. The Landlord Tenant Board explained that the burden of proof upon a landlord to show probability rather than just possibility that a tenant, or guest thereof, caused damage within S.M.O.F. whereas it was stated:
28. With respect to the Landlord’s application the issue that arises is related to the burden of proof. With respect to her damage claim, she bears the onus of leading sufficient evidence to establish that it is more likely than not that the Tenant, an occupant or a guest wilfully or negligently caused the damage. There is actually no suggestion in the evidence that anyone wilfully caused the plumbing problem. Rather the Landlord’s claim is that someone was negligent in how they use the toilet and that caused a blockage in the sewage line.
29. The Landlord’s evidence in this regard is entirely hearsay and circumstantial. Hearsay is admissible before the Board and circumstantial evidence can be sufficiently compelling to meet the burden of proof. But here the Landlord’s evidence essentially amounts to a belief that the Tenant or an occupant flushed something down the toilet they should not have. That belief is not unreasonable but there are other plausible explanations for what occurred.
30. As I stated at the hearing, it is possible that one of the Landlord’s contractors who were present in the residential complex working during the month prior to the incident flushed something they should not have. Further, and absent expert evidence from the Landlord’s plumber, it seems to me it is also plausible that the blockage was caused by something that had been in the sewage system for some time but had been recently dislodged because of the excessive rainfall on July 14, 2016.
31. In other words the evidence is insufficient to establish that it is more likely than not that the Tenant, an occupant or a guest negligently caused the plumbing problem. It is certainly possible, but the Landlord’s evidence does not establish it is probable.
Summary Comment
Cases involving disputes over responsibility for an overflowing toilet or sewage backup are often plagued by a landlord who believes that misuse by a tenant or guest of the tenant, is the cause of the problem. While the landlord may hold strong suspicions for the belief, the challenge for the landlord is to prove that misuse was the probable, rather than just a possible, cause.
NOTE: A significant number of online searches featuring “lawyers near me” or “best lawyer in” frequently indicate an urgent need for effective legal assistance rather than a particular title. In Ontario, licensed paralegals are governed by the same Law Society that regulates lawyers and hold the authority to represent clients in specified litigation issues. Core to their role are advocacy, legal analysis, and a mastery of procedures. Vagans Legal provides legal representation within its licensed framework, focusing on strategic positioning, preparation of evidentiary materials, and compelling advocacy designed to secure efficient and favourable outcomes for clients.
