In 35 years of building and inspecting I have encountered numerous water leaks with no apparent source. With some investigation the source of the leaking is usually discovered. Here are some of the most interesting mystery leaks:
Water next to a refrigerator: I am sure that someone reading this column has or will have the experience of water leaking out of the bottom of their refrigerator. This condition is especially mysterious if your refrigerator does not have a water dispenser or ice maker.
What your refrigerator does have, however, is a freezer. Your freezer is constantly producing condensation (water). This condensation flows to a drain that deposits it into a pan under the refrigerator. When operating properly, the condensation is dried out by the condenser motor in the refrigerator.
Sometimes, however, the drain gets clogged with food debris or sticky liquid. When this happens, water will run out onto the floor or into the refrigerator. For those of you that are handy, unclogging the drain is fairly easy, although accessing the drain can be aggravating.
Mystery stains on ceilings: If you have water stains somewhere on your ceiling and the roofer is stumped, the stains may not be from a leaking roof. If the stains appear only in winter, they may be related to your furnace flue. Often, especially in older homes, the furnace flue is inserted into your fireplace chimney. Since one of the by-products of the combustion in a gas-fired furnace is water vapor, any gaps in a brick chimney can allow this water vapor to escape. On a cold winter day the water vapor can condense on the bottom of the roof decking and drip down onto the ceiling. This will result in staining on the ceiling around the chimney. The solution here is to seal any gaps in your chimney brick.
Ceiling stains can also be the result of urine from pests in your attic or even in a floor system. If you have eliminated the potential for plumbing or roof leaks, try looking for evidence of a pest infestation. Some other signs that you have unwanted guests in your house are droppings and tracks or tunnels through insulation. If you discover that you have a pest infestation, there are many companies that can remove the pests and seal any openings in your house.
Water on the floor around a furnace: Water appearing on the floor around a furnace will typically only occur in the summer. However, if you happen to have a high efficiency, condensing furnace it can also occur in the winter. During the summer your air conditioner is not only cooling the air in your house but it is also drying the air out.
The moisture that your air conditioner draws out of the air is normally piped to the exterior of the house. Sometimes, the pipe becomes clogged. When it does, the water will leak onto the floor around your furnace.
Since an air conditioner will typically draw gallons of water from the air daily, you will end up with a fairly large amount of water around the furnace. To solve this problem, I recommend calling a licensed heating and cooling contractor. Although clearing the drain pipe is usually easy, a licensed professional will make sure nothing else is wrong with your heating and cooling systems.