Water & refrigerant leak detectors

This category holds two different kinds of leak detector, and it helps to know which one you need before comparing products. Water leak sensors are for homeowners, renters and landlords who want an alarm the moment water appears under a sink, beside a water heater or in a sump pit. Refrigerant leak detectors, often called freon leak detectors, are handheld instruments that HVAC technicians use to find where an air conditioner, heat pump or refrigerator is losing refrigerant. The short answer: most households want water sensors, while refrigerant detectors are mainly a technician's tool. Natural gas and propane leaks are a separate problem with separate products, covered in the gas detector category. The product buttons below go to Amazon, where you can check the live price and current availability.

Water leak sensors: where to place them

A water leak sensor is a small puck or pad with metal contacts on the bottom. When water bridges the contacts, the sensor sounds an alarm, sends a notification, or both. Placement does most of the work, so put sensors where leaks start rather than where water eventually shows up:

• Beside the water heater. Tanks and their fittings fail with age, and a slow drip can go unnoticed in a closet or basement.
• Behind or under the washing machine. Supply hoses are a common source of sudden, high-volume leaks.
• Under kitchen and bathroom sinks. Drain joints, supply lines and shutoff valves sit out of sight in cabinets.
• Near the dishwasher, refrigerator ice maker line and toilets. Small supply lines and wax seals can leak for weeks before damage shows.
• In or beside the sump pit. A sensor placed just below the rim can warn of a failed pump before the basement floods.
• Near the main water shutoff and the HVAC condensate pan. Both are common trouble spots, especially in basements and attics.

Sensors only detect water at the exact spot they sit, so place them flat on the floor at the lowest point where water would collect. The water leak detector guide covers placement in more detail.

Local alarms, smart alerts and automatic shutoff

Water sensors fall into three broad tiers, and the right one depends on how often someone is home to hear an alarm.

• Local siren only. The simplest sensors beep loudly when wet. They work without Wi-Fi or an app, but only help if someone is nearby to hear them.
• Wi-Fi or hub-connected sensors. These send a phone notification, which matters for vacation homes, rentals and anyone away during the day. Some connect directly to Wi-Fi; others talk to a small hub or gateway that links to the internet, which can extend range and battery life. Check whether a hub is included or sold separately. The smart water leak detector guide compares the approaches.
• Automatic shutoff valves. The step up is a motorized valve on the main water line that closes when a paired sensor detects water. Installation usually involves cutting into the supply pipe, so a plumber is often the right call. A shutoff limits damage even when nobody responds to an alert.

Whichever type you choose, test sensors periodically by touching the contacts with a damp cloth, and replace batteries on the schedule the manufacturer recommends. A sensor with a dead battery offers no protection, so app-connected models that report low battery have an advantage.

Why early water detection matters: mold and damage

The EPA notes that the key to mold control is moisture control, and that wet materials should be dried within 24 to 48 hours to help prevent mold growth. A sensor that catches a leak in minutes rather than days gives you a far better chance of meeting that window. Slow leaks inside cabinets and behind appliances are the ones most likely to rot subfloors and feed hidden mold. The guides on whether a water leak can cause black mold and how to get rid of mold from a water leak explain what to do if a leak has already caused damage.

Sensors cannot find leaks inside walls, under slabs or in buried lines. For those, professionals use moisture meters, thermal cameras and acoustic equipment, as described in the plumbing leak detection guide and the infrared water leak detector guide.

Refrigerant leak detectors: heated diode, infrared and corona

When an air conditioner or heat pump loses refrigerant, it loses cooling capacity. Running a system that is low on refrigerant can also overwork the compressor and, over time, contribute to compressor damage, which is one of the most expensive repairs in an HVAC system. Refrigerant detectors pinpoint where the gas is escaping so it can be repaired rather than simply topped off. The three main sensor technologies are:

• Heated diode (and related heated-sensor designs). A heated ceramic element reacts to halogenated refrigerants. These detectors are sensitive and widely used, but the sensor wears with use and needs periodic replacement.
• Infrared (IR). The detector measures how much infrared light the refrigerant absorbs. IR sensors tend to resist false alarms from other chemicals and usually last longer, though the instruments often cost more.
• Corona suppression. An older, generally lower-cost technology that detects changes in a high-voltage corona discharge. It can be more prone to false alarms from humidity, dirt and other vapors.

Sensitivity is usually quoted in ounces or grams of refrigerant per year; a smaller number means the detector can sense a smaller leak. Many technicians confirm an electronic alarm with bubble solution at the suspected joint. The refrigerant leak detector guide and the electronic leak detector guide go further into the trade-offs.

Who should use a refrigerant detector

Under the EPA's Section 608 rules, technicians who maintain, service, repair or dispose of equipment that could release refrigerant must be certified. A homeowner can own a detector, but recovering, recharging or opening the refrigerant circuit is work for a certified HVAC technician. If you suspect a leak because the system runs constantly, blows warm air or ices up on the refrigerant lines, the practical step is to call a technician. The AC leak detector guide covers the warning signs.

Our picks in this category

The Inficon TEK-Mate Refrigerant Detector is a handheld heated-sensor refrigerant detector from an established leak-detection brand, aimed at HVAC service work.

The Elitech ILD-200 Refrigerant Leak Detector is a handheld electronic refrigerant detector; check the listing to confirm its sensor type and the refrigerants it is rated for.

The Fieldpiece SRL8 Refrigerant Leak Detector is a heated-diode detector from a brand well known among HVAC technicians, with a flexible probe for reaching tight coils and fittings.

The YoLink Water Leak Sensor is a hub-based smart sensor that sends phone alerts through the YoLink app; the hub is required for remote notifications.

The Govee Water Leak Detector (3-pack) bundles several sensors with loud local alarms, a straightforward way to cover a water heater, washer and sink; some Govee versions add app alerts through a Wi-Fi gateway, so check the listing for what is included.

Related guides

Homeowners comparing water sensors can also read the moisture leak detector guide. For hidden and buried leaks, see the acoustic leak detector guide, the underground water leak detector guide and the thermal imaging leak detection guide. When a leak cannot be found, the guide to finding a leak detection pro explains what to expect.

On the HVAC side, brand-specific pages include the Fieldpiece leak detector guide and the Fieldpiece DR82 infrared refrigerant leak detector guide, and the ultrasonic leak detector guide covers sound-based detection of pressurized leaks.

References

• EPA: A Brief Guide to Mold, Moisture and Your Home
• EPA: Section 608 of the Clean Air Act
• EPA WaterSense: Fix a Leak Week