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Septic Smells Outside After Using the Shower

Gary Sprague
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An outdoor septic smell after a shower can be due to improper venting, but is usually caused by an issue with the leach field.

Septic Smells Outside After Using the Shower

Most homeowners whose houses are connected to septic systems forget that there is a septic tank located below their backyard until a problem develops. A septic smell outside after showering could be a sign of a serious problem with the septic system. Unfortunately, unless you want to stop showering and using your other plumbing fixtures, it's a problem that will need to be repaired sooner rather than later.

The Septic Tank

Dwellings that are not connected to a city sewer require a septic system. The beginning of the journey is the same with city sewage and a septic system, but instead of flowing from the house into the sewer, liquid and solid waste flows from the house into a septic tank. A septic tank is usually made of concrete but can also be made of fiberglass or polyethylene. In the septic tank, solids settle to the bottom and are broken down into sludge by natural bacteria, while liquids overflow through an outlet pipe and into a leach field.

The Leach Field

A leach field is usually made up of a series of perforated pipes run through a bed of underground gravel or soil. The liquid from the septic tank, also known as effluent, runs into the leach field and eventually exits the pipes through the perforations to be absorbed by the soil.

Plugged Leach Field

A septic smell after running the shower can be due to broken pipes or an overflowing septic tank, but it is most often caused by a leach field blockage or failure. A healthy leach field that is operating properly can often last 20 to 30 years. But if a leach field is improperly designed or installed it can fail. A leach field installed near trees will almost always develop problems, as tree roots are one of the main causes of leach field blockage and failure.

Signs of Leach Field Failure

A leach field that is failing or blocked can either back up into the septic tank and cause the drains inside the house to back up, or overload the leach field with too much liquid. In some cases it will do both. The water from a shower, especially a long one, can be enough to flood a plugged leach field. Signs of a failing leach field are a wet or spongy feeling in the leach field, thick growth of grass in the leach field, and a septic or sewer smell.

Vent Problems

All plumbing fixtures are equipped with a drain trap that prevents sewer gas from entering the dwelling through the drain pipes. Instead, the gas exits through vent pipes on the roof. If the vent pipe is too short or too high, the sewer gas smell can float down into the yard. Strong winds can also cause this to happen.

Septic Smell Solutions

Extending or reducing the height of a vent pipe will often prevent sewer gas issues. For a septic system, having the septic tank pumped regularly is the best way to keep the leach field clear and operating properly. If the tank is not emptied regularly, solids can build up and plug the leach field. Adding a monthly septic treatment can help maintain the proper bacterial balance to break down solid waste and clear out the leach field. Removing trees from the area will prevent roots from invading the leach field. If a leach field fails and cannot be cleared, it will need to be replaced.