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Smelly Basements - Don't panic

Written By:
R. Dodge Woodson

What is that awful smell in my basement? The odor has been growing for days and it’s getting worse. Did a mouse die in the basement? After searching the basement no source of the smell is found, but the odor wafts from the basement through the staircase and floors. What can I do about it? Who should I call?

All sorts of smells permeate homes. If you have an unidentified odor in your home, look to the plumbing fixtures in the area where the odor originates. Do you have a shower that is rarely used? Is there a floor drain in your basement or garage that doesn’t see regular use? These are two common areas of concern, but don’t rule out lavatories and sinks. Look for plumbing drains that don’t get much use.

All plumbing drains are required to be trapped. A trap is a device that holds water at all times. This water creates a seal between the drain pipe and the open air. In essence, the water seal prevents sewer gas from entering living space. Your mystery smell could simply be the result of a plumbing trap that has gone dry.

Okay, you have a dry trap. Should you call a plumber? No, just take a pitcher of water and pour it down the drain. Once the trap is filled with water, the odor should dissipate. I find that showers and floor drains are the two most common culprits where sewer gas invades a home.

Any plumbing trap that goes dry can release sewer gas. This gas is potentially dangerous. Don’t take it for granted. Pour water in floor drains once a month. Keep plumbing fixtures working periodically. This will eliminate the problems associated with dry traps.

What if my problem isn’t a dry trap? It could be a cracked or broken vent pipe that is emitting sewer gas into your walls, ceilings, or attic. These problems are much more difficult to find and usually require the services of a professional plumber. The venting system can be capped off and colored dye can be put into the system to expose leaks. Unfortunately, this can be an invasive process that requires cutting out sections of walls or ceilings.

Sometimes a septic field will emit odors that are trapped low to the ground from time to time. If you have basement windows open and have a septic system, take a walk though the septic field and see if you smell anything. If you do, there are two potential options.

Vent the septic field with a pipe that extends above your windows. It is a barometric event, this will certainly help. The very bad side of this is that your septic field may be failing. This is expensive and requires professional assistance.

Hopefully, your problem will simply be a dry trap.

R. Dodge Woodson is a master plumber of over 30 years. He has written over 90 books dealing with many subjects, including plumbing.