The roof vent and yard based septic vent is a necessary part of your plumbing system. The job of the plumbing vent is to enable the pressure in your drain system to equalize. When water and waste flows down your drains, pressure in your plumbing drains increases as the air in the system is displaced by water and waste. Without the plumbing vents, the drains would gurgle up into your sinks, tubs and toilets.

The plumbing roof vent and yard based septic vent is also a place where septic gases and sewer gases exit the system safely. These gases are a natural byproduct of the bacteria that break down the waste in either your septic system or sewer line. Because of this naturally occurring cycle, the septic and sewer gases have a foul odor. Normally, the gases are carried up and away from the system’s vent pipes. However, under certain conditions, these Hydrogen Sulfide (also known as H2S) and Methane gases might be pulled down into your yard around your home or place of business.

There is also a new style septic system design called a pressure dose septic system. This style septic system is becoming more popular as it utilizes both a solids and a liquid septic tank. By separating the liquid from the solids, it allows for a cleaner liquid to be pumped up into the leeching field allowing the leeching field to be significantly smaller than would be necessary in a standard septic system. For safety reasons, this style septic system requires that the liquid tank be vented to purge the Hydrogen Sulfide and Methane gases away from the electronic pump found in the septic tank. With pressure dose style septic systems, the septic gases are purged directly to the yard through a vent causing unpleasant odors, even under the best of conditions. This septic vent is typically located somewhere in the yard near the liquid tank.

If you notice foul odors coming from your septic vent, don’t assume that you have serious problems with your septic system. As we mentioned earlier, Hydrogen Sulfide is a normal by-product of the breakdown of wastes occurring within your septic system.

In certain situations the Hydrogen Sulfide that would normally exit your roof vent and be carried up and away, will actually be pulled down into your yard creating not only an annoying problem, but also an unhealthy living environment. (For health information concerning Hydrogen Sulfide see The Toxicology of Hydrogen Sulfide.)

Different climate conditions, such as temperature variances and change in wind direction, can direct the gases back toward your living area. This problem can be magnified by the location of your home as well. If your home is located against a hill or near objects taller than your roof vent, negative pressures can naturally develop pulling the septic gas or sewer gas down from your roof vent and into your yard or place of business. In the case of sewer lines, since they don’t utilize plumbing traps, your home or building’s roof vent can be an exit source for not only the sewer gases created within your structure but for all the homes and structures on your main sewer line.

While you can’t stop the creation of septic and sewer gases, you can eliminate the odor that is caused as they exit the roof or septic vent by installing a roof vent filter. There are a number of companies that manufacture these products, Simple Solutions Distributing (disclosure, I am a partner in this company) manufactures a number of different size filters available for homeowners. Our Wolverine brand filter is manufactured of solid materials that have been plastic welded. It comes with a 120-day money back guarantee. Simple Solutions also manufactures odor solutions for industrial and municipal applications such as lift stations and manholes.

Other companies that manufacture these types of filters are OdorHog.com and SweetAir.com.