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?
Subsurface irrigation reuse
Passive
One of 2 ways to meet this need. Cost, carbon, footprint and rankings are relative to other solutions for the same need, not absolute.
What your site needs
Landscaping/soil area suitable for subsurface application, and food-production reuse reactivated (currently deferred per Charter §3)
Pipes buried just under the soil of the garden that release cleaned used water around plant roots. The water goes straight to where plants drink, and nobody touches it at the surface. It waters the garden for free. It needs no pump only where the garden lies lower than the treatment outlet.
Distribution piping/emitters: 15-25 years (subsurface drip emitters clog and need periodic flushing or replacement)
Embodied carbon
Low
Space / material use
Medium
Output timing
Continuous process
Skill to repair
Basic
Regulation (FR example)
Greywater reuse is permitted under decret 2024-796 and the arrete of 12 July 2024, on an experimental basis until 31 December 2034, for laundry, indoor floor washing and vegetable-garden watering. Not permitted for drinking, cooking or bathing.
Levels are relative to the other options for this need, not absolute. Fewer dots is lighter.
Subsurface irrigation reuse (This page) Can I use it? Not in a flat · No rebuilding needed What does it cost me? Upfront cost: Low · Skill to build: Basic · Upkeep: Light · Change to daily life: Occasional · Works without the grid: Yes Choose it if you want your garden watered for free with your cleaned greywater.
Direct greywater diversion to toilet flushing Can I use it? Works in a flat · No rebuilding needed What does it cost me? Upfront cost: Low · Skill to build: None · Upkeep: None · Change to daily life: Daily · Works without the grid: Yes Choose it if you want to flush the toilet with shower water, with nothing to install or treat.
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.