Fermi question · Everyday
According to EPA WaterSense guidance available in 2026, about how many gallons of water does the average family use for showering each day?
Make a fast, defensible estimate before you reveal the reference answer. Think in factors, not exact recall.
What is your estimate?
Your result will appear here after you submit a guess.
Reference answer
Reveal the reference answer
≈ 40 gallons per day
Fermi estimates are judged by scale, so a reasonable approximation can still earn a strong score.
One way to estimate it
Estimate family shower use from people, shower frequency, duration, and flow.
- Family showers≈ 3 showers/day
- Water per shower≈ 13 gallons
- Estimate3 × 13 ≈ 40 gallons/day
Keep practicing
Try another question, or return to the daily challenge to build your personal sense of scale.