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?

Multi-stage filtration + UV disinfection

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 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 water a little more. It turns rain or raw water into water that is safe to drink, but the lamp needs electricity.

Cost

Medium

Upkeep

Seasonal

Skill to build

Intermediate

Lifespan

Filtration housing/media: 10-15 years; UV lamp itself needs replacement roughly annually (8,000-12,000 hours rated life)

Embodied carbon

Medium

Space / material use

Low

Output timing

On-demand/controllable

Skill to repair

Intermediate

Inputs

• Unheated water
• AC electricity

Outputs

• Potable water

Compare the 5 ways to meet this need

Levels are relative to the other options for this need, not absolute. Fewer dots is lighter.

• Multi-stage filtration + UV disinfection (This page)
  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.
• Solar still (solar distillation)
  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.

Sources

• Water filtration component lifespan industry sources (CleanWaterStore; SimplePure RO guide; ESP Water Products UV guide)

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.