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?
Passive
Note: Cost, carbon and footprint are broad judgements against comparable building approaches, not measured figures.
Separate drain pipes for the lightly used water from sinks, showers and the washing machine, kept apart from the toilet waste. Because this water is not mixed with sewage, it can be cleaned simply and used again, for the garden or for flushing. It saves water and eases the load on any treatment system.
The only option catalogued for this need so far, so there is nothing to compare it against.
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.