Can a blocked drain cause smell?

Author: Frank Howe  |  Last update: Friday, September 26, 2025

Drain smells are usually caused by sewer gas leaks or blocked drains.

Can a clogged drain cause a smell?

There could be odor-causing bacteria feeding on debris in your pipes. This process will give off a foul-smelling hydrogen sulfide gas, which smells like sewage or rotten eggs. Also, mold grows where it's warm and wet — and mold growth on the debris causing a drain clog can also cause a bad smell.

How do you unblock a smelly drain?

Baking soda, vinegar, and hot water are amazing home remedies when it comes to cleaning and destroying smells. You can start by running as much hot water into smelly drains as your water bill can stand. The hot water loosens matter effectively, which will promote flushing if there isn't a substantial clog.

Why does my house suddenly have a strong sewer smell?

These are the most common causes of sewer line clogs, broken or damaged sewer lines, and foul sewer odors in homes: Clogged drains and blockages. Blockages or backups from the city's sewer system. Tree roots that have intruded into the sewer line.

What does a blocked sewer smell like?

Sewer gas produces a very distinct rotten egg smell, caused when organic materials break down and decompose to form hydrogen sulfide. If you're unsure about the smell coming from your drains or sewers, call a licensed plumber who can perform an inspection or clear and clean blockages.

Shower Drain Smells Like a Sewer? Quick Easy Fix

Is it bad to breathe in sewer smell?

Yes, sewer gas is noxious, and in high concentrations, it can be toxic or lead to a loss of consciousness. For brief exposure to sewer gas, any resulting health symptoms will usually resolve themselves without medical intervention.

Who is responsible for smelly drains?

Generally speaking, you're usually responsible for drains inside the boundaries of your property, while the sewerage company is responsible for lateral drains, which are usually outside of property boundaries, and sewers. Although most sewers are now publicly owned, there are still some private or unadopted sewers.

Is it safe to stay in a house that smells like sewer?

Answer: Only under extremely unusual circumstances. Although hydrogen sulfide is a toxic gas, it will not harm people at the concentrations that exist in a house with sewer gas odor problems. Studies have shown that hydrogen sulfide has a depressant effect on the central nervous system in concentrations above 150 ppm.

Why does my drain smell like sewage but no blockage?

Mould Formation – Mould or mildew forms inside the pipes when there is a leak and water remains standing for a while. The mould can generate a stinking odour that you can smell even from behind a wall. Plumbing Issues – Sewer smell can also be caused due to incorrect plumbing fixtures.

How to tell where sewer smell is coming from?

Where is the odor coming from? Check your home's drains, toilets, and plumbing fixtures for any signs of leaks or damage. Look for cracks, loose connections, or broken seals allowing sewer gas to escape. Additionally, inspect your sewer vents on the roof or outside your home for any obstruction or damage.

What is the best product to get rid of smelly drains?

Try using vinegar and baking soda. Pour one cup of baking soda then one cup of vinegar down an outside drain then wait 20 – 30 minutes before pouring a large amount of boiling water down the drain. External drains can get blocked with mud which can be removed manually.

How to tell if a P-trap is dry?

Identifying a Dry P-Trap

Here are the signs to look out for: Persistent sewer gas odours near sinks or floor drains. Drains that gurgle or make unusual sounds. Infrequently used fixtures, such as guest bathrooms or utility sinks, are familiar places for dry P-traps.

How do you fix a smelly sewer drain?

How to Fix Stinky Drains for Good
  1. Run the disposal for 20 seconds every time you dispose of food down the kitchen sink.
  2. Pour a gallon of near-boiling water down the drain once a week.
  3. Occasionally run the water in rarely used sinks to keep the P-trap full of water. Adding mineral oil slows evaporation.

Why should you never use baking soda and vinegar to unclog a drain?

Baking soda is abrasive, which, when used in large quantities, will cause the drain more damage. Additionally, the acidic nature of vinegar can eat away rubber and metal, damaging the plumbing. As these products break down the pipe and connectors in the plumbing in your home, it will cause more clogs over time.

Can a plumber fix a smelly drain?

Plumbing Errors

Rotting drain tubes, missing traps or vents, and leaks can all contribute to a foul-smelling drain. Finding a stinky drain remedy can sometimes be the least of your worries – you may need to call licensed service professionals for help.

How do I know if my sewer drain is clogged?

10 Signs Your Sewer Line Is Clogged
  1. Multiple Fixtures Are Clogged. ...
  2. Flushing the Toilet Causes Water to Come Up Elsewhere. ...
  3. Water Draining From Your Washing Machine Causes an Overflow in Other Locations. ...
  4. Drainage at the Cleanout. ...
  5. Slow-Draining Sinks or Toilets. ...
  6. Frequent Plunging. ...
  7. Bubbles in Your Toilet Water. ...
  8. Dark Water.

Why does drain smell come and go?

Due to the frequent movement of water and waste through your plumbing system, and the varying use of different drains throughout the day, some issues can fluctuate. This means that you may only notice the symptoms of a problem, like a sewage smell, at certain times of the day or in response to certain action.

Can a blocked drain cause smell in house?

If the smell is inside your home or coming from a sink, bathroom or drain, in nearly all cases this will be an issue with your private plumbing. In that case you can use household drain cleaning products to clear or unblock the drain, which should solve the problem.

Why does my house randomly smell like sewer?

All drain systems in your house must be properly vented to prevent sewage gasses from seeping into your home. A clogged vent pipe can prevent sewer-smelling air from leaving your home. This situation often results in leaking odors, and they typically come from the walls around the vent pipe.

What are the symptoms of sewer gas poisoning?

Irritated eyes, nose, throat, and respiratory system, including tearing of eyes, cough, or shortness of breath. Effects may be delayed. Severe eye and respiratory irritation such as coughing and difficulty breathing. These symptoms may be accompanied by headache, dizziness, nausea, vomiting, and more.

How much does it cost to unblock a sewage drain?

Cost Factors of Cleaning and Unclogging Drains

The overall cost of drain unclogging will depend on the blockage type, for instance, a small blockage in a toilet or sink is normally only priced at around £50 to £70. However, a more extensive blockage deep in your drains could end up costing you around £150 to £200.

What is the best thing for smelly drains?

How to stop the smell
  • Carefully pour half a cup of baking soda down the plughole.
  • Pour one cup of vinegar down the plughole after the baking soda.
  • Let the solution foam up; leave it for an hour or more to work.
  • Pour hot boiling water down the sink after an hour to flush it through.

How to clear a main sewer line clog yourself?

Your step-by-step guide: How to clear a main sewer line clog
  1. Step 1: Loosen the cap on the drain pipe. ...
  2. Step 2: Open the cap and let the buildup drain out. ...
  3. Step 3: Feed the auger cable into the drain pipe. ...
  4. Step 4: Run the auger until the clog is clear—and beyond. ...
  5. Step 5: Hose down the pipe and auger cable.

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