Water Calculators

A growing collection of practical water, stormwater, drainage, and hydraulic calculation references.

Available calculator references

• Rainwater Harvesting Calculator
• Manning Equation Calculator
• Pipe Capacity Calculator
• Detention Storage Calculator
• Orifice and Weir Calculator
• Pump Horsepower Calculator

How to use these tools

These pages are intended for planning, education, screening, and preliminary review. Final engineering decisions should be checked using applicable standards, local criteria, detailed calculations, and professional judgment.