How much water to store

A family of four should store 12 gallons for three days. That's one gallon per person per day, the floor FEMA (opens in a new tab) publishes, and the Red Cross (opens in a new tab) uses the same range. Ten days for that family is 40 gallons. Thirty days is 120. The 90-day list does not add more stored water.

Cases of bottles, jugs, and a 55-gallon drum all count toward that same total. Add extra if you have pets. A 70-pound Labrador drinks more than a cat, so the table is people only.

Those rows are the FEMA floor. Four regions raise them.

Heat: a Fort Worth family of four

Southeast and Gulf Coast, Southern Plains, Southwest Desert, and California and Pacific Coast add half. People drink more when the house is hot and the power is out.

The worked example on how we calculate quantities is a Fort Worth family of four on the Southern Plains 10-day list. Start at 1 gallon a day. Times 4 people is 4 gallons a day. Times 10 days is 40. Heat adds half of 40, which is 20. The checklist says 60 gallons.

The same family, three days, is 18 gallons. Thirty days is 180. For a household that isn't four people, take your row in the table and add half. Three people for three days is 9 gallons at the floor; half of 9 is 4.5, so heat makes it 13.5.

Two weeks in Oregon and Washington

Oregon and Washington ask households to plan for two weeks. That's their Cascadia guidance: a quake can close roads for a long time. Four people at one gallon a day for 14 days is 56 gallons. That figure is on the Pacific Northwest page.

Our checklists are 3, 10, 30, and 90 days. There is no 14-day list. The live Pacific Northwest 10-day checklist for four people is 40 gallons. Two weeks is 16 gallons more than that 10-day number, and 64 gallons short of the 30-day number (120 gallons at the FEMA floor). Start at 10 days. Keep filling until you pass 56 on the way to 30.

The 30-day cap

Stored water stops at 30 days. Four people at the FEMA floor is 120 gallons. In heat it is 180. Past a month, a filter and a second source take over: a well you can work by hand, rain you treat, water you can haul. Same cap as how we calculate quantities. The 90-day list still has water gear. It does not add 360 gallons of stored water.

Water in a go-bag

A go-bag is not a short 3-day list. You cannot carry 12 gallons when you leave, so the go-bag holds 3 liters per person plus a backpacking filter. Build one bag per person. The bottles cover the walk and the filter covers the rest.

The water heater

A typical tank holds 40 to 50 gallons of clean water. Count it as a reserve behind the jugs you already stored, not as the plan. The California checklist treats a heater strapped to the studs as about 40 gallons you can drink. Stage a hose on the drain valve so you can get it out.