What Is a Tertiary Septic System?

Primary, secondary and tertiary treatment

It helps to think of septic treatment in levels. Primary treatment happens in the septic tank, where solids settle. Secondary treatment happens as effluent passes into a conventional leaching bed and the soil does its work. A tertiary system adds a further stage: a treatment unit that cleans the effluent to a higher standard before it's dispersed.

Why treat to a higher standard

That extra level of treatment opens up options. Because the effluent is cleaner before it reaches the ground, a tertiary system can often work on properties where a conventional bed is difficult, and can sometimes reduce the size of the dispersal area needed.

• Small or restricted lots where a full conventional bed won't fit
• Difficult soils or a high water table
• Higher daily design flows, including commercial properties
• Sites near sensitive features where higher treatment is called for

What a tertiary system looks like

A tertiary system generally pairs a septic tank with an advanced treatment unit — often a media-based filter — and a dispersal component. Infiltra is a qualified and certified installer for Waterloo Biofilter, Ecoflo and Eljen systems, so we can match the right unit to the property rather than forcing one solution onto every site.

Is it right for your property?

A tertiary system isn't automatically better, and it isn't a fix for every problem — it's the right answer when the site calls for it. Whether one is required or beneficial comes out of the design, based on your soil, your lot and your design flow. We'll tell you honestly what your property actually needs.