Rainwater Tank Size Calculator

Rainwater Tank Size

Determine the optimal rainwater storage tank size based on roof area, rainfall patterns, and daily water usage requirements.

Roof Area (sq ft)

Average Monthly Rainfall (inches)

Daily Water Usage (gallons)

Longest Dry Spell (days)

Formula

Monthly Collection = Roof Area x Rainfall x 0.623 x 0.8; Reserve = Daily Usage x Dry Days; Recommended Tank = Reserve rounded up to nearest 50 gallons

Frequently Asked Questions

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