How to Purify Water in an Emergency (Step-by-Step)

When municipal water fails or floodwater contaminates wells, you need a backup purification method.

Method 1: Boiling (Most Reliable)

1. Filter cloudy water through cloth or coffee filter
2. Bring to a rolling boil for 1 minute (3 min if above 6,500 ft elevation)
3. Let cool, store in clean containers

Kills: bacteria, viruses, parasites | Does NOT remove: chemicals, heavy metals

Method 2: Bleach Disinfection

For clear water only:

1. 8 drops unscented 6% bleach per gallon
2. Stir, wait 30 minutes
3. If no slight chlorine smell, repeat 8 drops and wait 15 more minutes

Method 3: Portable Filtration

• LifeStraw Personal — instant drink from bottles/streams; bacteria & parasites
• Sawyer Mini — inline filter for bags and bottles
• Big Berkey — countertop gravity filter for household volume

Method 4: Water Purification Tablets

Iodine or chlorine dioxide tablets work in go-bags. Follow package timing — typically 30–45 minutes.

What NOT to Do

• Don't drink floodwater, pool water, or water with chemical sheen
• Don't rely on filters alone for chemically contaminated sources
• Don't use scented or color-safe bleach

Bottom Line

Boil if you can, filter if you can't, bleach as backup. Keep at least two methods in your kit.