What causes sewer smells in your home?

Recent Sewer Smell Investigation in Wollondilly

Recently, we attended a home in the Wollondilly area where the homeowner had been experiencing an ongoing sewer smell in their bathroom.

After investigating the issue, we found the cause was a perished toilet pan connector. Over time, the rubber seal within the pan connector had deteriorated, allowing sewer gases to pass through and enter the bathroom.

To rectify the issue, we carefully removed the toilet pan without damaging the existing sand and cement bedding, replaced the faulty pan connector, and reinstalled the toilet. Once the new seal was installed, the sewer odour issue was resolved.

This highlights why sewer smells should never be ignored, as the cause is often hidden beneath fixtures or within the drainage system.

Dry Floor Wastes – One of the Most Common Causes

One of the most common causes of sewer smells we encounter throughout Bargo and Wollondilly is a dry floor waste trap.

Every floor waste relies on a water seal to prevent sewer gases entering the home. If the fixture supplying water to that floor waste isn’t used regularly, the water can evaporate over time.

A common example is a bath that hasn’t been used for several months. If the bath is the fixture responsible for charging the floor waste, the trap can eventually dry out and allow sewer odours to enter the room.

Floor wastes can also dry out due to:

• Drainage blockages

• Poor ventilation within the drainage system

• Trap siphonage caused by venting issues

When a drainage system is not adequately vented, water can be pulled from traps as other fixtures discharge, removing the water seal and allowing sewer gases to enter the building.

Dirty Traps Can Also Cause Odours

Not all sewer smells originate from the drainage system itself.

Shower wastes, floor wastes and basin traps can accumulate:

• Hair

• Soap residue

• Body fats

• Organic build-up

This build-up can create unpleasant odours that are often mistaken for sewer gas.

In some cases, hair or debris protruding over the trap weir can create a capillary or siphoning effect, slowly drawing water from the trap overnight. The trap may appear normal during the day but be dry by morning, resulting in sewer smells appearing seemingly at random.

Regular cleaning and maintenance of waste traps can often prevent these issues before they become a problem.

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