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?

Treatment / purification

Making water safe to drink. What has to be removed depends on the source: mud and bacteria from a roof or a stream, dissolved chemicals from some groundwater. The options differ in what they take out, how fast they work, and whether they need power or consumable parts.

Ranked by breadth of contaminant removal: turbidity -> bacteria/viruses -> dissolved solids and chemicals (PFAS, nitrates, salts). Reverse osmosis reaches the highest ceiling; passive filters cover microbial contamination only.

Solutions

• Multi-stage filtration + UV disinfection: A line of filters that removes sand and dirt, then a carbon filter for taste and smells, and finally an ultraviolet lamp that kills germs. Each stage cleans the
• Bio-sand filter: A tall container filled with layers of sand and gravel that water is poured into and slowly passes through. A living layer of tiny organisms grows on top of the
• Ceramic candle filter (silver-impregnated): A pot or candle of fired clay, treated with silver, that water slowly drips through by its own weight. The fine pores hold back dirt and most bacteria, and the
• Reverse osmosis (RO) filtration: A unit that forces water under pressure through a very fine membrane that lets water pass but holds back salts, metals, nitrates and other dissolved pollutants.
• Solar still (solar distillation): 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,