Sewage Smell in House: 6 Causes and How Plumbers Track It Down

Sewer gas smells like rotten eggs and it is not just unpleasant — hydrogen sulfide and methane are hazardous in concentration. Here is where the smell usually comes from.

Six common causes

• Dry P-trap. A floor drain or guest bathroom that is rarely used lets the water seal evaporate. Pour a quart of water down it.
• Failed toilet wax ring. Gas escapes at the base; see toilet repair.
• Blocked or broken vent stack. Traps get siphoned dry and gas is pulled into rooms.
• Cracked sewer line under the house. Needs sewer line repair.
• Biofilm in a drain. Bacteria in the overflow or drain produce odor; drain cleaning removes it.
• Water heater bacteria. Smelly hot water only means the anode rod is reacting — see water heater repair.

How we find the source

We run a smoke test on the drain system and a sewer camera inspection to pinpoint cracks or breaks. If the line is damaged, trenchless sewer repair usually fixes it without digging up the yard.

Need a plumber in Idaho?

Santaana Emergency Plumbing serves every city in Idaho with 24/7 emergency service and same-day appointments. Find your city or call (888) 480-9811.