Pressure Dosed Drainfields

We all know what we want when we are looking for our dream home. Maybe it’s a large master bath, hardwood floors, or open concept living. The one item that is never on the list is a pressure dosed drainfield. In fact, we would rather not even discuss what happens to our wastewater. But the fact of the matter is that what happens to our wastewater can affect home values more than granite counter tops or stainless steel appliances.

According to the United States Environmental Protection Agency, one in five households in the United States depend on onsite sewage treatment and disposal systems (SOURCE: EPA). In many of these households, the sewage systems consist of a septic tank and an absorption field. Wastewater flows from the home to the septic tank for primary treatment, and then from the septic tank, the effluent flows via gravity to the absorption field.

Despite the popularity of gravity systems, multiple counties in Montana have moved away from this type of wastewater disposal system. These counties, including Lake County and Flathead County, are now requiring pressure distribution systems. These systems consist of a septic tank, a pump chamber, a pump and controls, small diameter laterals and the absorption field.

The main advantages of pressure distribution are that the effluent is equally distributed throughout the absorption field, the field is dosed periodically, and the laterals can be shallowly installed. The periodic dosing at shallow depths allows a resting cycle, promotes evapotranspiration, and enhances growth of aerobic bacteria. All of these factors provide better treatment of the wastewater and add longevity to the system.

The advantages for the homeowner of pressure distribution systems versus gravity systems go beyond just treatment. Absorption fields, depending on site conditions, can now be located on slopes up to 35%, they can be placed upslope from the home site, and they can utilize a smaller footprint.

The communities that our TLI team serves in Montana are fortunate to have local expert septic system installers. These contractors are smart, savvy and great resources when it comes time to install a new drainfield or upgrade your old system.

So the next time you go to build a new home or replace your drainfield, consider installing a pressure dosed drainfield. And maybe in the future, we will hear homeowners ask Alexa or Siri, “how many times has my drainfield been dosed today?”.

by Shawn Rowland, RS, MS, Project Manager