When the stored water runs low

Drinking rules

"Never ration drinking water unless ordered to do so by authorities. Drink the amount you need today and try to find more for tomorrow." Reduce activity and stay cool to need less. (Ready.gov — Water)

Drink water you know is not contaminated first. Suspicious water can be used after treatment. If you can't treat it, put off drinking it as long as possible, but don't become dehydrated. (Ready.gov — Water)

Don't drink carbonated or caffeinated drinks instead of water. Caffeine and alcohol dehydrate the body. (Ready.gov — Water)

Water already in the house

EPA says you may find water by melting ice cubes or draining your hot water tank or pipes. (EPA — Emergency disinfection)

FEMA's 2004 guide lists safe sources: melted ice cubes; water drained from the water heater (if the heater isn't damaged); liquids from canned goods such as fruit or vegetable juices; water drained from pipes. (FEMA 2004 p. 39)

• EPA — Emergency disinfection of drinking water
• FEMA, Are You Ready? Part 1 (2004 PDF)
• Archived copy

Never drink these

CDC: "Never use water from radiators or boilers that are part of your home heating system for drinking, cooking, or hygiene." (CDC — Make water safe)

FEMA's 2004 guide also lists as unsafe: water beds ("fungicides added to the water or chemicals in the vinyl may make water unsafe"); water from the toilet bowl or flush tank; swimming pools and spas, whose chemicals "are too concentrated for safe drinking," though the water can be used for personal hygiene and cleaning. (FEMA 2004 p. 39)

• CDC — Make water safe in an emergency
• FEMA, Are You Ready? Part 1 (2004 PDF)
• Archived copy

Distillation: the only home method here that removes salts and chemicals

Ready.gov says boiling and chlorination kill most microbes. Distillation also removes microbes that resist them, plus heavy metals, salts, and most other chemicals. (Ready.gov — Water)

Fill a pot halfway with water. Tie a cup to the handle on the pot's lid, so the cup hangs right-side-up when the lid is upside-down. The cup must not dangle in the water. Boil for 20 minutes. The water that drips from the lid into the cup is distilled. (Ready.gov — Water)

Source: Ready.gov — Water (same table in FEMA 2004 p. 41).

• Ready.gov — Water
• FEMA, Are You Ready? Part 1 (2004 PDF)
• Archived copy

Safety

You cannot make water containing fuel, toxic chemicals, or radioactive materials safe by boiling or disinfecting it. Use bottled water or another source, and call the health department. (CDC — Make water safe)