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?
Membrane bioreactor (MBR) greywater recycling package unit
Needs the grid
One of 5 ways to meet this need. Cost, carbon, footprint and rankings are relative to other solutions for the same need, not absolute.
A packaged machine that cleans the used water from sinks and showers with bacteria and then a fine membrane filter. The water that comes out is clean enough to flush toilets indoors, not just to water the garden. It needs power all the time and specialist servicing.
Build it
This solution is not buildable as a DIY project.
Cost
High
Upkeep
Seasonal
Skill to build
Specialist
Lifespan
15-20 years for the package unit; membranes need periodic replacement (fouling is the main failure mode, per its own description)
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.
Membrane bioreactor (MBR) greywater recycling package unit (This page) Can I use it? Works in a flat · No rebuilding needed What does it cost me? Upfront cost: High · Skill to build: Specialist · Upkeep: Heavy · Change to daily life: None · Works without the grid: No Choose it if you want greywater clean enough to flush toilets indoors.
Constructed wetland / reed bed filtration Can I use it? Not in a flat · No rebuilding needed What does it cost me? Upfront cost: Low · Skill to build: Intermediate · Upkeep: Light · Change to daily life: None · Works without the grid: Yes Choose it if you have room and a slope, and want greywater cleaned by plants with no power.
Sand filter Can I use it? Works in a flat · No rebuilding needed What does it cost me? Upfront cost: Low · Skill to build: Basic · Upkeep: Regular · Change to daily life: None · Works without the grid: Yes Choose it if you want a compact filter for greywater, on its own or ahead of a reed bed.
Greywater heat recovery (drain water heat exchanger) Can I use it? Works in a flat · No rebuilding needed What does it cost me? Upfront cost: Medium · Skill to build: Intermediate · Upkeep: Light · Change to daily life: None · Works without the grid: Yes Choose it if you want to get back the heat of shower water, with nothing to switch on.
Wood-chip filter (Filtres a Broyat de Bois, FBB) Can I use it? Not in a flat · No rebuilding needed What does it cost me? Upfront cost: Low · Skill to build: Basic · Upkeep: Regular · Change to daily life: None · Works without the grid: Yes Choose it if you want the simplest greywater filter to build, topped up with wood chips.
Sources
General MBR package-plant manufacturer durability consensus
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.