Your landlord must keep the unit in a good state of repair and fit to live in, and must comply with health, safety and maintenance standards. That obligation holds even if you knew about the problem when you moved in, and no lease clause can contract out of it.
Ask in writing, every time
Email or text, not a phone call. You are building a record. A verbal request you cannot prove is worth very little later.
Describe the problem, the date it started, and its effect. "The kitchen tap has dripped since 3 March and the cupboard beneath is now swollen" beats "the tap needs fixing".
Photograph it, with a date.
Ask for a timeline, and follow up in writing when it passes.
This is the single most damaging mistake tenants make. Withholding rent is not a lawful remedy in Ontario, even where the landlord is plainly in breach. It converts your maintenance complaint into an arrears case that you will lose, and it can cost you the tenancy.
Nor should you pay for a repair and deduct it from the rent without an order permitting it.
When nothing happens
Municipal property standards. Often faster than the Board. An inspector attends, and a work order carries real weight. Free, and available in every GTA municipality.
A T6 application to the Landlord and Tenant Board: maintenance. Remedies include a rent abatement for the period you were without something, an order to do the work, and reimbursement of costs.
A T2 application: interference with reasonable enjoyment, illegal entry, harassment, or a lockout. Different form, different grounds, and the two are often filed together.
Both cost a filing fee, both are decided at a hearing, and both take months rather than weeks. Your evidence is the written record you built at the top of this page, which is why it matters.
No heat in winter, no water, a gas smell, an electrical hazard, or major flooding are not maintenance requests. Call the landlord, then the municipality's emergency line, and in a genuine emergency call the fire service or utility directly. Document everything afterwards.
Forms, fees and procedures change. Confirm the current requirements with the Landlord and Tenant Board, and a tenant duty counsel or legal clinic can help you prepare an application at no cost.