When the bathroom drains start to smell, it’s time to call a plumber.

According to Stephen Mewett of the Master Plumbers Association of New South Wales, "If there’s a smell, it means there’s generally something wrong with the system, and it needs to be fixed."

Stephen says the most common source of bad smells in the bathroom is a waste outlet. "You have a waste outlet under your bath tub, basin and toilet, and the sewer smell is sealed from the room by means of a water seal inside," he says.

"But sometimes this water can dry up, leaving the pipes open for awful smells to waft in." This evaporation of the water usually occurs when the shower or bath is not being used on a regular basis, such as in a second bathroom. Faced with warmer-than-average autumn weather, the water can dry up in as little as a month. Often, running the shower or bath for a few minutes, or pouring a bucket of water down the waste outlet, can fix the problem.

Shower drains can also be a major cause of bad bathroom odours. "When people shower, the grease or fats that come off their skin can sometimes set or congeal on the walls of the waste pipe," says Stephen.

"If there’s a fair distance between the floor and the water seal, there’s more chance that the build-up of fats will create an odour." A plumber can clear this build-up, but Stephen says it is a problem that would normally require ongoing maintenance. "I would generally advise the household to put bleach down there on a regular basis, otherwise they’ll keep getting the smell," he says.

Stephen stresses the importance of bathroom maintenance having a plumber check out any problems, to properly evaluate the cause and advise a strategy for maintenance. "If it’s not a waste outlet or a shower drain causing the smell, it’s even more important that a plumber looks at it, because it could mean that the system has not been sealed properly," he says.

In addition to being unpleasant, he reveals that a stinky bathroom can also be bad for you. "If those smells are straight from the sewer, it can be dangerous to your health, as disease can spread from the sewer to the occupants of the house," he says.

If you’ve got a stinky bathroom, Yellow Pages can help you find a plumber in your local area today.