Calculating GPM for HOA Irrigation Connection to City Meter

Determining Required GPM for HOA Irrigation System Connection

An HOA needs to provide GPM (gallons per minute) requirement to water district for new city meter connection after shared supply was cut off.

Information Needed for Accurate Calculation

• Irrigation system design drawings (should specify GPM)
• Whether supply serves common areas only or also homes
• Largest zone sprinkler count and types

Estimation Method Without Drawings

1. Identify largest zone by area/head count
2. Count spray heads × 1.85 GPM each
3. Count rotors × 3.09 GPM each
4. Sum = peak zone GPM requirement
5. Add 10-15% safety factor

Example Calculation

Largest zone: 20 spray heads + 8 rotors

• 20 × 1.85 = 37 GPM
• 8 × 3.09 = 24.7 GPM
• Total = 61.7 GPM + 15% = ~71 GPM

Professional Verification Recommended

For HOA systems, hire irrigation professional to verify. Undersized meter causes chronic low pressure; oversized increases connection fees.