FEMA says store one gallon per person per day for three days. That’s the floor, not the ceiling, and it assumes you’re sedentary in mild weather. California in summer, after a major earthquake, with no power and a damaged water main — you’re going to need more than that.
Why California’s Water System Is Fragile
In a significant earthquake, water mains can rupture at scale. After the 1994 Northridge earthquake, water service was disrupted for hundreds of thousands of customers for days to weeks. Extended PSPS events disable the pumps that move water through distribution systems. A cracked main can draw in contaminated groundwater — meaning tap water isn’t safe even after pressure is restored.
Step 1: Storage
Two gallons per person per day is realistic for warm weather with any physical activity. For a family of four planning for seven days: 56 gallons minimum. Fourteen days is better.
Containers: WaterBOB bathtub bladder (100 gallons, $30–50, great for known events). 7-gallon Aquatainer jugs (stackable, manageable). 55-gallon drums (stationary, need a pump). Avoid: milk jugs and juice containers — the plastic degrades and protein residue harbors bacteria.
Step 2: Sourcing When Storage Runs Out
- Hot water tank: Your home’s water heater holds 30–50 gallons. Close the cold water inlet valve, drain from the tank’s drain valve. Filter and treat before drinking.
- Swimming pool: Not potable without treatment, but a significant source. With proper treatment, pool water can be made drinkable.
- Natural sources: Treat all natural water as contaminated. Giardia, Cryptosporidium, agricultural runoff.
- Rainwater: A 1,000 sq ft roof in 1 inch of rain yields about 600 gallons.
Step 3: Purification
Know at least two methods. Equipment fails; chemicals run out.
Boiling: Rolling boil for 1 minute (3 minutes above 6,500 ft). Gold standard for biological contamination. Requires fuel.
Filtration: Sawyer Squeeze (0.1 micron, 100,000+ gallon rating, should be in every go-bag). Berkey gravity filter for home base camp use. LifeStraw as emergency backup only.
Chemical: Unscented household bleach — 8 drops per gallon of clear water, let stand 30 minutes. Chlorine dioxide tablets (Katadyn MP1) for broader pathogen coverage. Pool shock (calcium hypochlorite) for bulk storage.
Don’t Forget Sanitation Water
You need water for more than drinking. Toilet flushing, handwashing, wound care. Separate “potable” from “sanitation” water in your planning. Pool water and non-treated collected water — fine for flushing, fine for washing with soap, not for drinking without treatment.
Water is where most California households are most underprepared. Fix this one first.
