The short answer
Sewer Gas Is a Common Culprit
The distinct smell of rotten eggs often points to sewer gas. This gas contains hydrogen sulfide, which creates the sulfurous odor. It can leak into your home if a floor drain or unused sink trap dries out. Blocked or damaged plumbing vents on your roof can also allow the gas to back up and seep in near walls.
Check any floor drains in basements or utility rooms. Pouring a gallon of water down the drain can refill the trap and block the gas. If the smell persists, the issue may be a cracked drain line inside the wall. In this case, a plumber can inspect the hidden plumbing to find the break.
Natural Gas Leaks Are an Emergency
Natural gas companies add a chemical called mercaptan to give gas its warning odor. If you smell this near a baseboard, treat it as an emergency. Do not operate light switches or any electrical devices. Evacuate everyone from the home immediately and call your gas utility from a safe distance outside.
The pros do not handle natural gas leaks. Only your utility company has the equipment and authority to locate and stop the leak safely. Once they secure the leak, you can address any related water damage from the incident. This might involve drying out walls if the leak caused condensation or other moisture issues.
Steps to Investigate the Odor Safely
Start by checking all plumbing fixtures and drains near the smelly area. Look for signs of water damage on the baseboard, floor, or lower wall, such as staining, warping, or soft spots. Use your nose to see if the odor is stronger near a particular drain or appliance. Listen for the sound of running water inside a wall when no taps are on.
If you suspect a water leak, turn off the water supply to that area of your home to prevent more damage. For sewer gas, systematically refill all drain traps. If the source remains unclear, the next step is professional help. Document any visible damage for your insurance company, as policies vary, and your insurer decides what is covered.
When to Call Water Damage Professionals
Call local water damage pros if your investigation points to hidden water. They use tools like moisture meters and infrared cameras to map the extent of wet materials without destructive probing. They can pinpoint the leak's origin, which is essential for proper repair. Their assessment helps you understand what needs drying, cleaning, or replacement.
The pros then develop a drying plan to remove moisture from structural materials. This process prevents ongoing rot and odor. They can also advise on necessary repairs to plumbing or building materials once the area is dry. Addressing the water problem correctly is the only way to permanently eliminate a moisture-based rotten egg smell.
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Call Now (208) 537-2633Frequently asked questions
Can this smell be dangerous to my health?
Yes. Sewer gas contains hydrogen sulfide and methane, which can cause headaches and nausea in low concentrations. Natural gas is flammable and poses a risk of explosion. Bacterial growth from water damage can also degrade indoor air quality. If you feel unwell, leave the area and seek fresh air.
Will homeowners insurance cover the repairs?
It might, if the cause is a sudden, accidental event like a burst pipe. Damage from long-term seepage or lack of maintenance is often excluded. You must file a claim with your insurance company for their determination. Policies vary, and your insurer decides what is covered.
What if the smell goes away but comes back?
An intermittent smell strongly suggests a recurring problem, like a slow leak that only drips when water is used or a drain trap that periodically dries out. The underlying issue is not resolved. Persistent problems require professional leak detection to find the hidden source and prevent further damage.