Poor Ventilation A lack of proper ventilation in the bathroom can lead to trapped moisture and lingering odors. Without adequate airflow, humidity from daily use, such as showers or baths, can create a musty or unpleasant smell, especially if the bathroom doesn’t have an exhaust fan or open windows.

Leaking Wax Seal The wax seal, which creates a watertight seal between the toilet and the drain, is essential for preventing leaks and odors. Over time, this seal can deteriorate, leading to a slow leak of water and sewage gases, which can result in foul smells around the base of the toilet.

Clogged Toilet Drain or Sewer Line A clog in the toilet’s drain or a more extensive blockage in the main sewer line can cause waste to back up, leading to unpleasant odors around the toilet. A clog can prevent proper drainage, causing waste to linger and emit foul smells.

Dirty Toilet or Tank Bacteria, mold, and mildew can accumulate on the toilet itself or inside the tank, causing odors. Regular cleaning helps, but over time, grime can build up in hidden areas like under the rim, inside the tank, or in the bowl, even if it looks clean from the outside.

Sewer Gas Leaks If the vent stack, which is designed to release gases from the plumbing system, is blocked or damaged, sewer gases can escape into the home. These gases typically have a strong, unpleasant odor and can cause health problems if inhaled in large quantities.

Dry P-Trap The P-trap is a curved section of pipe under the toilet that holds water to create a barrier, preventing sewer gases from entering the home. If the toilet is rarely used (e.g., in a guest bathroom), the water in the P-trap may evaporate, allowing unpleasant gases to enter the bathroom.

Toilet Drain Issues If there is a problem with the toilet’s drain or the flange that secures the toilet to the floor, it could lead to odors escaping from the plumbing. This could be due to a loose connection or damaged components that allow air and waste to escape.

Mold or Mildew Growth Mold and mildew thrive in damp, poorly ventilated areas. If there is consistent moisture around the toilet, it could lead to mold growth under the toilet or in nearby areas, causing unpleasant odors.

Check for Leaks Around the Toilet Look around the base of the toilet for any water or dampness that might indicate a leaking wax seal. If the floor is wet, it could be a sign that water is escaping and mixing with waste, causing odors.

Inspect the Toilet Tank Lift the toilet tank lid and check for any signs of mold, mildew, or debris. Clean the tank thoroughly to remove any buildup that may be contributing to the smell.

Examine the Bathroom Ventilation Ensure that the bathroom has proper ventilation. Turn on the exhaust fan and check if it’s working efficiently. If there’s no fan, or it’s not functioning well, consider installing one to improve airflow.

Inspect for Clogs or Backups If the toilet is slow to flush or water backs up, it’s a sign that there may be a clog. Try using a plunger or drain cleaner to clear the clog. If the issue persists, it could indicate a blockage in the main sewer line.

Check for Dry P-Traps If the toilet isn’t used frequently, check the P-trap to see if the water inside has evaporated. You can pour water down the toilet to restore the seal and prevent sewer gases from escaping.

Smell Around the Plumbing Vents If you suspect that sewer gases may be entering through a damaged vent stack, check the outside of the house for any issues with the vent pipe. You may need a plumber to inspect and repair the venting system.

Replace the Wax Seal If the wax seal is leaking, it will need to be replaced. This involves removing the toilet, cleaning the area, and placing a new wax ring before reinstalling the toilet. This should restore the seal and prevent odors.

Fix Any Clogs or Blockages If you find a clog in the toilet drain or sewer line, use a plunger to try to clear it. For stubborn clogs, consider using a drain snake or calling a plumber to clear the line. Make sure the toilet and the plumbing are draining properly to avoid lingering smells.

Improve Bathroom Ventilation Increase ventilation by installing or repairing an exhaust fan in the bathroom. Make sure it’s vented to the outside and working properly. If necessary, open windows regularly to improve airflow and reduce moisture.

Clean the Toilet and Tank Thoroughly clean the toilet, including under the rim, around the base, and inside the tank. Consider using a toilet bowl cleaner with disinfectant and a tank cleaner to eliminate bacteria and mold.

Seal Leaks in the Plumbing System If there are any leaks or gaps in the toilet drain, wax seal, or plumbing vents, repair them immediately. Replacing damaged components will prevent sewer gases from escaping into the bathroom.

Pour Water into Dry P-Traps If the toilet is rarely used, make sure to periodically pour water down the toilet to fill the P-trap and create a barrier against sewer gases.

Address Mold and Mildew Growth If mold or mildew is found around the toilet or in the bathroom, clean the area with a mold-killing cleaner or a mixture of bleach and water. Ensure the area stays dry to prevent further growth.