How much iodine is needed to disinfect 5 gallons of water?

• A. 1-2 tsp
• B. 1-2 Tbsp
• C. 1-2 Cups
• D. 1-2 Drops

Answer: (A)

Disinfecting water with iodine is done by adding a measured number of drops per quart, depending on how clear the water is. For clear water, about 5 drops of tincture of iodine per quart is typical; for cloudy water, about 10 drops per quart. Let the water sit for about 30 minutes after adding the iodine.

Five gallons equal twenty quarts. If you treat clear water, you’d use 5 drops per quart × 20 quarts = 100 drops, which is roughly 1 teaspoon (since 1 teaspoon is about 5 mL, and ~100 drops ≈ 5 mL). If the water is cloudy, you’d double it to about 200 drops, which is roughly 2 teaspoons. So the amount to add for 5 gallons falls in the range of 1–2 teaspoons.