Lifewater Engineering Company offers aboveground and belowground ExtremeSTP® residential sewage treatment plants. Aboveground units are specifically designed for areas where permafrost, bedrock or other ground or soil conditions make it impractical to install a belowground system. For the aboveground systems, the preferred location for discharge is to undisturbed, natural vegetation such as a black spruce forest floor, the tundra surface, or a peat bog. Higher capacity systems are available for larger homes and apartment buildings.

For an alternative to a sewage treatment system, please see our Separett® waterless toilets.

  • Operate at -60°F (-53°C), provided reliable electrical power is available
  • Do not corrode and never need painting
  • Sized to be aircraft transportable to remote northern communities
  • Utilize submerged, fixed film, activated sludge aerobic sewage treatment
  • Effluent is suitable for surface discharge
  • Effluent pump included
  • Influent lift pump optional
XSTP® Bedrooms on Hauled Water Bedrooms on Well Water
SST300 3 2
SST300-LS 3 2
SST600 4 4
SST600-LS 4 4
SST650-UG 4 4
MBR500 3 3


  1. LS → Lift-station is built-in
  2. UG → Belowground system
  3. All models have effluent pumps

Cut Sheets

Standard aboveground STPs have a double-walled, fully insulated tank designed to be installed outdoors above the ground surface. They are available with or without a built-in inlet lift station (depending on the elevation of the sewer line coming from you house compared to the elevation of the STP). All STPs have an effluent pump. Drawings for a simple treated timber foundation are available.

Uninsulated aboveground STPs are available for installation inside a heated enclosure.

Standard belowground STPs have a single-walled, fully insulated tank designed to be installed below the ground surface with 4 inches to 4 feet of soil cover. Every system has an effluent pump, so treated effluent can be discharged either above or below the ground surface.

The following optional equipment is available for residential or small commercial use:

  • Built-in lift station (to lift raw sewage up into an aboveground treatment plant)
  • External arctic outdoor lift station (that can be mounted to the outside of a house or be set partially into the ground)
  • Thermosyphon (to keep the permafrost beneath the system frozen)


We will work with you to define your need and determine the best solution. Then we will quote a system or product that will work for you.