Water Leak Loss Calculator
Estimate how much water and money is lost from a leak over time, based on drip rate or continuous flow.
Typical slow drip: 10–30 | Fast drip: 60–120 | Near-stream: 200+
US average ≈ $3–$8 per 1,000 gallons. Check your utility bill.
Formulas Used
Dripping Faucet:
Flow Rate (gpm) = (Drips/min × 0.25 mL) ÷ 3,785.41 mL/gal
One drip ≈ 0.25 mL (USGS standard drop volume)
Continuous Flow:
Flow Rate (gpm) = user-supplied value
Stream by Diameter (Torricelli / Orifice Equation):
v = Cd × √(2gh) | Q = A × v
where Cd = 0.61 (sharp-edged orifice), g = 9.81 m/s², h = 10 m (assumed supply head ≈ 14.5 psi)
Total Water Lost:
Volume (gal) = Flow Rate (gpm) × Duration (minutes)
Cost:
Cost ($) = [Volume (gal) ÷ 1,000] × Rate ($/1,000 gal)
Assumptions & References
- One drip volume = 0.25 mL (USGS Water Science School standard).
- Stream diameter calculation assumes a typical residential supply pressure head of 10 m (≈ 14.5 psi) and a sharp-edged orifice discharge coefficient Cd = 0.61.
- Average US water cost ≈ $3–$8 per 1,000 gallons (EPA WaterSense, 2023). Check your utility bill for accuracy.
- Month = 30.4167 days (365.25 ÷ 12); Year = 365.25 days.
- Bathtub capacity ≈ 36 gallons; 8-minute shower ≈ 17.2 gallons (EPA); HE washing machine ≈ 19 gallons/load (Energy Star).
- 1 US gallon = 3.78541 liters.
- This calculator does not account for pressure variation, pipe friction losses, or sewer/wastewater surcharges (which can double the effective cost).
- References: USGS Water Science School; EPA WaterSense Program; AWWA (American Water Works Association) leak loss guidelines.