How long do water purification tablets last?
Most chlorine dioxide and iodine water purification tablets last about 4–5 years unopened; iodine tablets should be used within about 1 year of opening the bottle.
| Water Purification Tablets | |
|---|---|
| Unopened | About 4–5 years (check the package) |
| Opened | Iodine tablets: about 1 year after opening; individually foil-packed tablets keep their printed date |
| Ideal storage | Cool, dry and tightly closed; moisture ruins them. |
Storage tips
- Tablets do not remove chemicals or sediment; pre-filter cloudy water.
- Follow the contact time on the label, which is longer for cold water.
Signs it has gone bad
- A broken or loose seal on a commercial bottle
- Cloudiness, floating particles, green tint or algae
- A chemical, plastic or fuel smell (plastic absorbs odors from nearby chemicals)
- If in doubt, treat it before drinking (boil, filter, or disinfect) rather than discarding it in an emergency