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?
Solar still (solar distillation)
Passive
One of 5 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
Unshaded south-facing ground or roof area, sized to the water wanted
A shallow black tray of water under a sloping sheet of glass. The sun evaporates the water, which condenses on the glass and runs into a channel as clean water, leaving salt, metals and germs behind. It makes safe drinking water from almost any source, even salty water, but slowly, and some chemicals pass through.
Levels are relative to the other options for this need, not absolute. Fewer dots is lighter.
Solar still (solar distillation) (This page) Can I use it? Works in a flat · No rebuilding needed What does it cost me? Upfront cost: Low · Skill to build: Basic · Upkeep: Light · Change to daily life: Daily · Works without the grid: Yes Choose it if your only source is salty or badly polluted and you have sun.
Multi-stage filtration + UV disinfection Can I use it? Works in a flat · No rebuilding needed What does it cost me? Upfront cost: Medium · Skill to build: Intermediate · Upkeep: Heavy · Change to daily life: None · Works without the grid: No Choose it if you want the whole house on safe drinking water from rain or raw water.
Bio-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: Daily · Works without the grid: Yes Choose it if you want safe drinking water with no electricity, from a filter you can build.
Ceramic candle filter (silver-impregnated) 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: Daily · Works without the grid: Yes Choose it if you want drinking water with no power from a pot on the counter, with nothing to build.
Reverse osmosis (RO) filtration 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 your water carries nitrates, metals or salts and you want the purest drinking water.
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.