Water damage can occur almost anywhere in your house. Water-using appliances and fixtures, such as refrigerators with icemakers, dishwashers, washing machines, toilets and water heaters are common locations of leaks.

Unfortunately, slow leaks at these appliances and fixtures are often times impossible to see until it is too late. If it goes undetected, a slow leak can lead to rotting house framing and sub-floors, and can be a precursor to a catastrophic leak that can release several gallons of water per minute, causing extensive water damage. A water leak detection system may help prevent these problems.

Leak detection systems can be either active or passive.

Passive leak detection systems are intended to alert you of a leak. They generally sound an audible alarm tone and some may also feature a flashing light.

Passive systems are frequently battery-operated, stand-alone units. They are inexpensive and easy to install. Some simply sit on the floor while others may be wall mounted. A moisture sensor is located on the floor and activates the alarm when it becomes wet.

Battery-operated devices need to be checked regularly and the batteries should be changed at least every year. Most devices will "chirp" when the battery is low, similar to smoke detectors.

Passive systems only help reduce water damage if someone hears the warning tone and acts to stop the leak. They are especially useful in locations where it is easy for someone to hear the alarm such as near refrigerators, dishwashers, or toilets.

Active leak detection systems usually generate some type of alarm, but also perform a function that will stop the water flow. They feature a shut-off valve and some means to determine that a leak is occurring. Most devices use moisture sensors to detect a leak. Other systems use a flow sensor and a timer to determine that something is leaking and the water needs to be turned off.

An active leak detection system can either operate at an individual appliance or it can operate and control a whole house.

Individual Appliance systems are designed to detect a leak from an appliance, such as a washing machine or water heater. When a leak is detected, an alarm is activated and the water supply to the appliance is automatically shut off.

Depending on the type of device, the homeowner may be able to install these systems without any special tools. However, in some cases a qualified plumber may be needed.

Whole house systems shut off the main water service when a leak is detected. An automatic shut-off valve is installed on the main water service piping between the water meter and first branch piping. This valve usually requires 115 volt electrical service. Some models feature a battery back-up.

Some whole house systems monitor several moisture sensors (also called water sensors). These detectors are installed on the floor below water-using appliances and fixtures.

These detectors may be hard-wired, meaning a wire must be routed through the home between the sensors and the control valve, or wireless. Wireless systems utilize battery-operated sensors that send a radio signal to the control valve if a leak is detected. The wireless systems are usually easier to install, especially in existing homes. However, because each sensor has a small radio transmitter, these systems often cost more. The batteries in wireless systems also must be regularly maintained and replaced.

Some whole house systems use a flow sensor and timer that are programmed to accommodate the water usage patterns of the home. When water usage exceeds the programming, the device sends an alarm and shuts off the water service. Most of these devices feature "at-home" and "away" settings for when the home is or is not occupied.

Convenient Features of Some Leak Detection Systems

Some control panels can identify which moisture sensor detected the leak while some can only identify that there is a leak. Knowing which moisture sensor detected a water leak will make it easier to find and repair the problem.