We recently had a call in which a slab home was experiencing water in the ductwork which was run under the slab when the home was built.
The question of course, was where was it coming from?
The possibilities are three fold. The water could be sewage from the drain pipes under the slab. Or it could be fresh water from a water line leak under the slab. Lastly it could be condensate from the air conditioner or a humidifier overflowing if in the winter.
How do you tell which it is?
A sewage leak is pretty easy to diagnose. Usually, even if it’s only the bathtub or the lavatory, it really smells bad. If the water in the ducts is smelly or less than clear, get your plumber to start looking for the source right away. This is a severe health hazard and needs to be addressed right away.
Pressurized Water Line
If the water is clear and seems to be refilling the ductwork quickly after pumping the water out, it is most likely a pressurized water line that is leaking. Have your plumber do a diagnosis to confirm this is the case and you are on your way to solving the issue.
Humidifier & Condensate Waste Lines
If the water is clear but takes a long while to refill the ductwork after being pumped out, then you need to have the plumber look at the humidifier and condensate waste lines at the furnace.
While leaks under slabs are hard to find, they are not impossible to fix. With a little detective work and some plumbing skills, repairs can be made and you can move on with your day.