Boiling vs Filtering Drinking Water

Boiling is a disinfection method: it kills bacteria, viruses and protozoa. It removes nothing dissolved and nothing particulate.

Filtering is a removal method: carbon reduces chlorine, taste and some chemicals; certified cartridges remove lead, cysts and other named contaminants; RO removes dissolved solids.

The overlap is small. A boil advisory is about microorganisms, and a household carbon filter is not a disinfection device.

Whenever your utility issues a boil-water notice, and for the duration they specify. Bring water to a rolling boil for the time stated — usually one to three minutes depending on altitude and the notice's wording.

Let it cool covered, and store it in a clean container. Boiled water is safe microbiologically but can pick up contamination from a dirty jug.

Boiling does not fix chemical contamination, and it does not make water from an unknown source safe.

For taste and odour from chlorine or chloramine, and for named health contaminants that appear in your water report — lead, cysts, PFAS, nitrate.

For routine everyday drinking, filtration is the practical tool. Boiling every glass of drinking water is energy-intensive and unnecessary when the supply is compliant.

If a health contaminant is the concern, look for the certification claim naming it. Nothing else substitutes for that.

During a boil advisory, boil first, then cool, then filter for taste if you like. Filtering does not replace boiling and can put a microbiologically loaded cartridge in your system.

After the advisory is lifted, flush your plumbing and replace any cartridge that was in service during the event if the water was visibly dirty.

For a supply that is both microbiologically uncertain and chemically contaminated, treat disinfection first, then filtration — and consider whether the source should be used at all.

Assuming a filter makes boil-advisory water safe. It does not disinfect.

Assuming boiling removes lead, nitrate or PFAS. It concentrates them slightly instead.

Boiling and then storing in an unwashed container, which undoes the disinfection.

Using hot tap water to save time: hot water dissolves more lead and spends time in the tank.