When it's the sound of a happy baby or a gentle stream, a gurgling noise can be absolutely lovely. When the drains in your bathroom constantly gurgle, it can be a sign that something is wrong with your drainage. A small amount of gurgling can be perfectly harmless while the water drains, but if it happens loudly each and every time, and the sound lingers, then you need to investigate. It is often coupled with slow draining water. So what can loud, ongoing gurgling actually signify? And what do you need to do to correct it?
The Drain Waste Vent System
The water from your home flows out of the building via a drain waste vent system. The water exits through a pipe that has a trap which always contains water. This trap exists to prevent sewer gasses and other noxious substances from entering your home. The trap flows into the vent itself, which is maintained in a state of neutral air pressure, allowing the water (and waste products) to flow downwards and exit your home into the sewers. This air pressure is maintained by a rooftop air vent, which is usually protected by a cover known as an air admittance valve (AAV) that allows air to enter the drain waste vent system, and yet (mostly) keeps debris out. This looks like a small chimney on the roof of the building.
A Blockage in the System
Loud, ongoing gurgling can mean that there is a blockage in the drain waste vent system, preventing water from draining freely. This is usually a blockage in the system itself, rather than a blockage in the pipes directly beneath the area being drained (your bath, shower, or basin). When wastewater is released into the vent system, the AAV briefly opens to admit air which keeps the air pressure inside the system in a neutral state. More often than not, a gurgling sign is a signal that the AAV is not functioning correctly. If left unchecked, it can create significant problems with your home's drainage.
Can You See the Blockage?
You will need to get up on the roof, or you can ask a plumber to do this for you if you don't feel capable. Take the proper precautions, and only do this in good weather, wearing appropriate footwear that has sufficient traction. Inspect the AAV. The problem might be immediately obvious if it has become clogged with leaves and other garden debris. Rather unpleasantly, it might be a dead rodent that has attempted to enter your home via the AAV and has become stuck. If the debris is obvious and you can clear it safely, then do so. This might remedy the problem.
When You Need to Call a Professional
If the debris is not obvious, then you really should consult a plumber. The plumber can remove the AAV without damaging it, before running a plumber's snake down into the drain waste vent system. It's a straightforward process, but it is difficult to do without the necessary tools and expertise. This should dislodge the blockage and return your drains to their former (gurgle-free) selves.
So the next time you brush your teeth, listen for the gurgle. If you think it's lasting for too long, it might be time to call a plumber and head up to the roof.