A dual-focus guide on water management. Part 1 dives into the physics of rainwater catchment, cistern sizing, and filtration. Part 2 covers irrigation efficiency, evapotranspiration, and calculating exact water needs for your landscape.

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plumbing

The Physics of Comfort: A Deep Dive into HVAC Sizing, Manual J, and Tonnage

HVAC sizing is not a guessing game. This comprehensive guide explains Manual J Load Calculations, the definition of a Ton of cooling, SEER ratings, and why oversizing your AC unit is the worst mistake you can make.

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plumbing

Hot Water Logistics: Sizing Tank vs. Tankless Water Heaters

Never take a cold shower again. We explain First Hour Rating (FHR) for tanks and Temperature Rise/GPM for tankless units. Compare the pros, cons, and payback periods of both technologies.

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How to Use This Calculator

Roof area.

Rainfall.

Get Gallons.

Understanding Rainwater Harvesting Calculations

0.623 gal/sqft/inch.

First flush.

Storage.

Uses.

Formula & Calculations

Area x Rain x 0.623

Key Factors to Consider

Roof material

Filter

Tank size

Overflow

Frequently Asked Questions

11 inch rain?

600 gal per 1000 sq ft.