Lowtech Graph lists low-tech options for every need of a home. Here you can compare them, find tutorials to build them, and link them together into a circular system. Why low-tech?
Aerobic treatment unit / micro-station d'epuration (package plant)
Needs the grid
One of 4 ways to meet this need. Cost, carbon, footprint and rankings are relative to other solutions for the same need, not absolute.
A compact buried treatment plant where a small pump blows air into the sewage so bacteria that need oxygen can break it down fast. The water comes out cleaner than from a septic tank, and it fits small plots or wet ground where a drain field would fail. It needs power all the time and regular servicing.
Build it
This solution is not buildable as a DIY project.
Cost
High
Upkeep
Frequent
Skill to build
Specialist
Lifespan
15-20 years for the package plant; the aeration blower is the usual mid-life replacement item
Embodied carbon
Medium
Space / material use
Low
Output timing
Continuous process
Skill to repair
Specialist
Regulation (FR example)
On-site sanitation (assainissement non collectif): the installation must be declared to and approved by the local SPANC before work starts, and is subject to periodic inspection. Arrete du 7 septembre 2009 modifie.
Levels are relative to the other options for this need, not absolute. Fewer dots is lighter.
Aerobic treatment unit / micro-station d'epuration (package plant) (This page) Can I use it? Not in a flat · No rebuilding needed What does it cost me? Upfront cost: High · Skill to build: Specialist · Upkeep: Heavy · Change to daily life: Occasional · Works without the grid: No Choose it if your plot is small or wet, where a drain field would fail.
Septic tank + drain field Can I use it? Not in a flat · No rebuilding needed What does it cost me? Upfront cost: Medium · Skill to build: Intermediate · Upkeep: Light · Change to daily life: Occasional · Works without the grid: Yes Choose it if you are off the sewer and have a garden for a drain field.
Constructed wetland blackwater treatment Can I use it? Not in a flat · No rebuilding needed What does it cost me? Upfront cost: Medium · Skill to build: Intermediate · Upkeep: Light · Change to daily life: Occasional · Works without the grid: Yes Choose it if you want all your wastewater treated on site by planted beds, with no power.
Mains sewer Can I use it? Works in a flat · No rebuilding needed What does it cost me? Upfront cost: Medium · Skill to build: Specialist · Upkeep: None · Change to daily life: None · Works without the grid: Yes Choose it if the house is on the public sewer and you want nothing to maintain.
Sources
Aquatiris / BioMicrobics (commercial) + Environmental Finance Center Network
Limitations of this page
We don’t list sizing or quantities, as the yield of each technique depends on the quality of its build. The catalogue compares options but doesn’t dimension them. Regulatory notes are indicative, with a French example, and need to be confirmed locally.