This is a classic condo leak investigation scenario and it's worth walking through clearly because the building management is actually doing the right thing by pushing it back to you — even if it feels frustrating. Here's what's actually going on and how to handle it intelligently.

The leak is described as originating near the tub and toilet and manifesting in the hallway, which means water is travelling. In a condo, water almost never leaks straight down — it follows framing, subfloor, drywall paper, and vapour barriers before it shows up visibly, sometimes travelling 4–8 feet from the actual source before appearing. This is why management can't find it: the symptom location and the source location are likely different.

The three most common culprits in this configuration are: (1) a failed wax ring or closet flange at the toilet base — this leaks only during flushes and can be completely invisible between uses; (2) a deteriorated tub surround seal or grout — water intrudes behind tile during bathing and travels along the liner or backer board before finding an exit point; (3) a slow supply line or shutoff valve weep at the toilet that's been wicking for months. Less commonly, a cracked drain trap or loose drain basket at the tub can be the culprit.

On the question of whether to hire any plumber vs. a specialist: for a leak this elusive, a standard residential plumber with a moisture meter and some diagnostic experience will often find it — especially if they do a methodical dye test at the toilet and a controlled water test at the tub. However, if the standard plumber can't locate it (which happens when water is travelling behind finished walls), then yes, you want someone with a thermal imaging camera or an acoustic leak detection device. Thermal cameras are the most useful here because they show temperature differentials behind drywall caused by evaporative cooling of wet building materials — they can pinpoint a wet patch behind a wall in minutes without any demolition.

Practically speaking: look for a plumber who explicitly advertises leak detection services, not just general residential plumbing. In Toronto/Etobicoke, several plumbing companies own thermal cameras or partner with restoration companies that do. You can also call a water damage restoration company (ServiceMaster, Paul Davis, BMS CAT) directly — they often do leak detection for free or at low cost hoping to win the remediation work, and they always own thermal cameras. That's a legitimate shortcut.

On the condo responsibility question — this is important: in Ontario, the Condominium Act and your condo's declaration/rules define who owns what. Generally, the unit owner is responsible for everything inside the unit boundary (including your toilet, tub, supply lines, and drain stack up to the main stack). The corporation owns common elements and the main stack. If the leak source turns out to be a common element (main stack, building supply riser), the corporation pays. If it's your toilet wax ring, you pay. This is exactly why management wants you to hire a plumber — they're appropriately pushing you to do the investigation first. Keep all invoices and documentation; if the source turns out to be a common element, you can seek reimbursement. If it's causing damage to the unit below, your condo insurance (unit owner's policy) is what pays — report this to your insurer now, before the investigation, so there's a claim file open. Do not wait until after you know the source.