Flood Water Intrusion Volume Calculator
Calculate the volume of flood water intruding into a structure or enclosed area based on floor area dimensions and the depth of water intrusion. Results are provided in cubic feet, cubic meters, and gallons.
Percentage of floor area occupied by furniture, walls, etc. (0–95%)
Formula
Flood Water Intrusion Volume
V = L × W × (1 − O/100) × d
- V = Intrusion volume (ft³)
- L = Length of the structure or area (ft)
- W = Width of the structure or area (ft)
- O = Obstruction / furniture coverage (%)
- d = Water intrusion depth (ft) = depth in inches ÷ 12
Unit Conversions:
- 1 ft³ = 0.028317 m³
- 1 ft³ = 7.48052 US gallons
- 1 ft³ of fresh water ≈ 62.4 lb ≈ 28.3 kg
- 1 m³ of fresh water = 1,000 kg
Assumptions & References
- Water is assumed to be fresh water with a density of 62.4 lb/ft³ (1,000 kg/m³). Salt water is approximately 64 lb/ft³.
- The floor area is assumed to be rectangular. For irregular shapes, calculate each rectangular section separately and sum the results.
- The obstruction factor accounts for walls, furniture, appliances, and other solid objects that displace water volume. A typical residential interior uses 5–15%.
- Water depth is assumed to be uniform across the entire effective floor area.
- Pump-out time is estimated using a standard 1/3 HP residential sump pump rated at approximately 2,000 US gallons per hour under low head conditions. Actual rates vary by pump model, head pressure, and hose length.
- This calculator does not account for water absorbed by porous materials (carpet, drywall, insulation), which can significantly increase total water removal time.
- References: FEMA Flood Insurance Claims Data; ASHRAE Fundamentals Handbook; U.S. Army Corps of Engineers Flood Damage Assessment Guidelines.