How much water do I actually need for a camp shower?

Across the reviewers we read, a 'navy shower' (wet, lather with the water off, rinse) typically uses 1–2 gallons per person. A 5-gallon bag or jug is enough for two conservative showers; a 2–3 gallon system is one person, one wash. Specialist-subreddit users consistently flag that high-pressure pumps blow through water faster than expected, so factor flow rate, not just tank size.