Smelly Drains: The Cause of the Smells and How to Fix Them

how to fix smelly drains

If you have smelly drains and need a solution, read on with my tips.

In the last week I have noticed a funky smell from our ensuite bathroom – and no, it wasn’t something nasty in the toilet!! The smell was a distinct drain smell and I knew it was coming from our shower waste.

This can be a common problem in most households and it can be easily fixed.

The shower waste trap (bottom of the pipe running from the ground to the shower grate) holds water to form a water seal to stop the main sewer smell to travel up the pipes into your bathroom.

This is why you have a ‘s’ or ‘p’ trap on your fixtures (bath, basin, sink, laundry tub and toilet).

Sometimes though, the bottom of the trap holds sediment and bacteria from hair, soap and shampoo and conditioner. It can also sometimes hold wee if a person does a number one in the shower.

Over time, this sediment is what can cause the ‘dead drain’ smell.

I knew this was what was causing the smell in our bathroom because I recognized it from fixing the problem in client’s bathrooms.

All that was needed to fix it was to take the shower grate off and the floor waste grate off and use a special liquid that only licensed plumbers can purchase called Mo-Flo.

Mo-flow is sulphuric acid that dissolves all organic blockages and sediment without damaging your pipes.

It needs to be left in the drain for 10 minutes and eats away the hair and black sediment that has settled at the bottom of the trap. After the 10 minutes, the shower has to run for 10-15 minutes to flush it out of the floor waste into the main sewer.

This formulation can only be purchased by plumbers and for use by plumbers. It is similar to Mr Muscle’s Draino that can be purchased from a supermarket, but Mo-flo is more potent and much more effective.

The smelly drain is no longer a problem in our bathroom.

I have found that the drains that smell the most are those bathrooms that are used by girls with long hair because as they wash their hair, they also lose it down the drain and over time this accumulates at the bottom of the floor waste and decomposes.

Another reason why a drain can smell is if the bathroom hasn’t been used for a while and the water at the bottom of the floor waste has dried up which is allowing the main sewer smell to enter your bathroom.

This is a simple fix by running a tap and the water from the basin waste or shower waste (providing the water running from them goes into the floor waste) will automatically fill up the floor waste and create a water seal to stop the smell.

Does your bathroom suffer from smelly drains? What have you used to clear the air?