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Quick answer
Put leak sensors where water is most likely to appear and where damage would be most expensive. Start under and near every water-using appliance and hidden leak point. A leak sensor alerts you — it does not stop the water unless it is connected to an automatic shutoff system.
Best places to put leak detectors
Where to place water leak detectors
- Under every sink — kitchen, bathroom, laundry, bar sink
- Behind and beside the washing machine
- Near the dishwasher — on the floor beside the toe kick
- Beside the water heater — on the floor or inside the drip tray
- Beside the sump pit — on the floor or slightly above normal water level
- At the lowest point on the basement floor
- Near toilet supply lines — especially on upper floors
- Behind the refrigerator if it has an ice maker or water line
- In the mechanical room near any water connections
- Under and near a humidifier
- Near a water softener or filtration system
- Under vulnerable exterior-wall plumbing — pipes in outside walls in cold climates
Priority order
Priority order by number of sensors
| Decision | Minimum | Better | Overkill |
|---|---|---|---|
| First 3 sensors | Under kitchen sink, near water heater, behind washing machine | Kitchen sink, water heater, washing machine | Kitchen sink, water heater, washing machine plus dishwasher |
| Next 3 sensors | Near dishwasher, under bathroom sinks | Dishwasher, master bath sink, near sump pit | Dishwasher, sump pit, refrigerator ice maker line |
| High-risk basement setup | Near sump pit, at lowest floor point, near water heater | Sump pit, water heater, washing machine, floor drain area | Multiple sensors around basement perimeter plus cable sensors along walls |
| Condo or rental setup | Under kitchen sink, near washing machine if applicable | Kitchen sink, bathroom sink, washing machine | All sinks plus behind toilet and near dishwasher |
| Smart-home or shutoff setup | Sensors paired with automatic shutoff valve locations | Full sensor network covering all risk points | Sensors plus flow monitoring plus cable sensors throughout basement |
Sensor type by location
Sensor type by location
| Spec | Why it matters | Look for | Marketing sludge to ignore |
|---|---|---|---|
| Basic puck sensor | Simple, cheap, loud local alarm. Best for under-sink and appliance locations. | Loud alarm (85 dB+), replaceable battery, low-profile design to fit under cabinets. | Sealed disposable units that become e-waste. |
| Wi-Fi sensor | Sends phone alerts when you are not home. Best for primary risk areas. | Loud local alarm plus reliable push notifications. Check offline behaviour. | App-only alerts with no local alarm. |
| Hub-based sensor | More reliable communication in larger homes or basements with weak Wi-Fi. | Mesh or proprietary radio protocol that reaches the hub from the basement. | "Works with any hub" if the hub is not included and compatibility is unclear. |
| Rope or cable sensor | Covers a long area — along a basement wall, behind a row of appliances, inside a drip tray. | Cable length that covers the target area. Compatibility with the alarm system. | Short cables sold as perimeter coverage. |
| Temperature and leak combo sensor | Detects both leaks and freezing conditions. Valuable in basements, crawl spaces, and exterior-wall plumbing. | Freeze alert temperature range that matches your climate. Leak detection still works if the temperature sensor fails. | Temperature alerts with no clear freezing threshold. |
| Shutoff-linked sensor | Triggers an automatic shutoff valve when water is detected. Best for supply-line risk areas. | Compatibility with the shutoff valve system. Sensor cable length reaches the shutoff controller. | "Works with any shutoff valve" without confirmed compatibility. |
Placement mistakes
Condo and renter note
Leak detectors are one of the few water damage prevention tools that renters and condo owners can use without modifying plumbing. Battery-powered puck sensors or Wi-Fi sensors that sit on the floor require no installation and no permission.
If you own a condo unit on an upper floor, a leak in your unit damages your neighbour’s ceiling too. A few well-placed sensors are worth it.
Major plumbing or shutoff modifications require owner, board, or building management approval. If you detect a leak in a rental or condo, alert the building management or landlord quickly — delays increase the damage for everyone.
Canadian context
Canadian homes have specific leak risks that make sensor placement important:
- Exterior-wall plumbing — pipes running through outside walls in Canadian winters are vulnerable to freezing and bursting. A sensor near these pipes can catch a thaw leak early.
- Basement mechanical rooms — often the coldest, most humid part of the house, with multiple water connections and no one checking regularly.
- Older plumbing — many Canadian homes have galvanized steel, copper, or CPVC supply lines that develop pinhole leaks as they age.
- Municipal water pressure — varies by neighbourhood but can be high enough to turn a small leak into a significant water loss quickly.
Health Canada recommends using electrical products with recognized Canadian certification marks (CSA, cUL, cETL). This applies to any plug-in or battery-powered sensor.
Additional guidance
- Consult manufacturer sensor manuals for specific placement and installation guidance
- Check with your insurer and municipal authority for guidance relevant to your property
Related links
- Water leak detectors
- Automatic water shutoff valves
- Basement flooding prevention
- Prevent frozen pipes
Frequently asked questions
How many water leak detectors do I need?
For a typical Canadian home, start with three: under the kitchen sink, near the water heater, and behind or beside the washing machine. Add more as budget allows — near the dishwasher, under bathroom sinks, beside the sump pit, and behind the refrigerator if it has an ice maker. Each sensor covers a small area, so coverage matters more than sensor count.
Where should I put my first leak detector?
Under the kitchen sink. It is the most-used water location in most homes, has multiple connection points, and a leak here damages cabinets, flooring, and potentially the ceiling below.
Should leak detectors go under the washing machine?
Yes, but beside it, not directly under it. Washing machine leaks often spread sideways or come from supply hoses at the back. Place the sensor on the floor beside the machine, close to the supply connections.
Do leak detectors work in basements?
Yes, but check for Wi-Fi range first — many routers struggle to reach a basement sump pit through concrete floors and walls. Wi-Fi sensors in basements may need a hub-based system or a mesh Wi-Fi node nearby. Basic battery-powered puck sensors with loud local alarms work regardless of Wi-Fi.
Are Wi-Fi leak detectors worth it?
Wi-Fi sensors add remote phone alerts, which are valuable when you are not home. The best approach is a sensor that does both: loud local alarm plus phone notification. Avoid sensors that only send app alerts with no local alarm.
Can leak detectors prevent water damage?
Leak detectors cannot stop water — they alert you to a problem. But early warning can mean the difference between a towel cleanup and a flooring replacement. For automatic water shutoff when a leak is detected, pair sensors with a compatible automatic shutoff valve.
Official sources used
Health Canada
Recognized Canadian certification marks and electrical product warnings.