Water Leak Cost Calculator Formula

Understand the math behind the water leak cost calculator. Each variable explained with a worked example.

Use the Water Leak Cost Calculator

Formulas Used

Annual Water Wasted

annual_waste = annual_gal

Annual Cost of Leak

annual_cost = annual_gal * water_rate / 1000

Daily Waste

daily_waste = daily_gal

Monthly Cost

monthly_cost = annual_gal * water_rate / 1000 / 12

Variables

VariableDescriptionDefault
drips_per_minDrips per Minute(drips)10
drip_volume_mlVolume per Drip(mL)0.05
water_rateWater Rate(USD/1000 gal)5
daily_galDerived value= drips_per_min * drip_volume_ml * 1440 / 3785.41calculated
annual_galDerived value= daily_gal * 365calculated

How It Works

How to Calculate Water Leak Costs

Even a slow drip wastes significant water over time.

Formula

Daily Gallons = Drips/min * mL/drip * 1,440 min/day / 3,785.41 mL/gal

Annual Cost = Daily Gallons * 365 * Rate

Common Leak Rates

  • Slow faucet drip (10/min): ~3,000 gal/year
  • Running toilet: 200+ gal/day
  • Pinhole pipe leak: 10-50+ gal/day

    • Worked Example

    A faucet dripping 10 times per minute, 0.05 mL per drip, at $5/1000 gal.

    drips_per_min = 10drip_volume_ml = 0.05water_rate = 5
    1. 01Daily waste: 10 * 0.05 * 1,440 / 3,785.41 = 0.19 gallons
    2. 02Annual waste: 0.19 * 365 = 69 gallons
    3. 03Annual cost: 69 * $5 / 1,000 = $0.35
    4. 04Note: A faster drip or running toilet wastes far more

    Ready to run the numbers?

    Open Water Leak Cost Calculator