1. What is the Residential Irrigation Equation?

The Residential Irrigation Equation calculates the precipitation rate (PR) from flow rate (GPM) and area. It helps determine how much water is being applied to a landscape area per hour.

2. How Does the Calculator Work?

The calculator uses the Residential Irrigation equation:

Where:

• \( PR \) — Precipitation rate (inches/hour)
• \( GPM \) — Flow rate in gallons per minute
• \( Area \) — Area in square feet

Explanation: The equation converts flow rate and area into an application rate that can be compared to plant water requirements.

3. Importance of Precipitation Rate Calculation

Details: Calculating precipitation rate is essential for efficient irrigation system design, ensuring proper water distribution, and preventing over- or under-watering.

4. Using the Calculator

Tips: Enter GPM (gallons per minute) and area in square feet. All values must be valid (greater than 0).

5. Frequently Asked Questions (FAQ)

Q1: What is a typical precipitation rate for residential lawns?
A: Most residential lawns require 1-2 inches per week, which translates to about 0.15-0.3 inches per hour for typical irrigation schedules.

Q2: How do I measure my GPM?
A: You can measure GPM using a flow meter or by timing how long it takes to fill a known container (e.g., 1 gallon in 10 seconds = 6 GPM).

Q3: What if my area is in acres?
A: Convert acres to square feet by multiplying by 43,560 (1 acre = 43,560 sq ft).

Q4: Why is the constant 96.3 used?
A: The constant 96.3 converts gallons per minute per square foot to inches per hour (1 gallon = 231 cubic inches, 60 minutes/hour, 12 inches/foot).

Q5: How does this relate to irrigation scheduling?
A: Knowing your precipitation rate helps determine how long to run your irrigation system to apply the desired amount of water.