Water Treatment — Printable 18×24 Wall Chart, Nine Methods Against Six Contaminants

 A matrix, because this is a question with a matrix answer and every other format loses the part that matters.

Nine methods down the side — boiling, a 0.2 micron filter, a purifier, iodine or chlorine, chlorine dioxide, a UV device, solar disinfection, distillation, and an improvised filter. Six contaminants across the top — bacteria, viruses, protozoa, cryptosporidium, chemicals and salt. Every cell marked: handles it, partly or slowly, or does not.

Each row carries its working note. Boiling: one minute at a rolling boil, three above 6,500 feet. Chlorine dioxide: thirty minutes, but up to four hours for crypto. SODIS: six hours of bright sun, two days if cloudy, clear PET bottles. Distillation: slow, and the only method on the chart that handles salt water.

The part the chart exists for is at the bottom — the three gaps that make people ill. Most filters do not remove viruses. Iodine and chlorine do not kill cryptosporidium. An improvised charcoal filter makes water clear, not safe, and always needs disinfecting after.

The conclusion it argues for: carry two methods that work by different principles, because any one of them will fail eventually.

A single sheet, 18 × 24 inches. Print it at any copy shop, office store or online print service — ask for 18 × 24 on matte or satin paper. You get a print-ready PDF and a PNG.

Adapted from public-domain US government field manuals and CDC and EPA guidance, redrawn and set fresh. Field guidance, not medical advice, and not an official publication or endorsed by any agency. Instant download — print it as many times as you like.