| Depth (cm) | Velocity (m/s) | Duration (h) | Contamination | Debris | Criticality | Utilities | Basement | Score | Class |
|---|---|---|---|---|---|---|---|---|---|
| 8 | 0 | 1.5 | Clean | Low | Residential | NO | NO | 0 | Class 1 (Minor) |
| 35 | 0.6 | 10 | Grey | Med | Commercial | YES | NO | 11 | Class 2 (Moderate) |
| 110 | 2.2 | 48 | Black | High | Critical | YES | YES | 21 | Class 4 (Extreme) |
Risk Score = Depth points + Velocity points + Duration points + Contamination points + Debris points + Criticality points + Utilities points + Basement points.
| Factor | Points |
|---|---|
| Depth (cm) | <10=0, 10–29=1, 30–59=2, 60–119=3, ≥120=4 |
| Velocity (m/s) | <0.30=0, 0.30–0.99=1, 1.00–1.99=2, 2.00–2.99=3, ≥3.00=4 |
| Duration (hours) | <2=0, 2–5.9=1, 6–23.9=2, 24–71.9=3, ≥72=4 |
| Contamination | Clean=0, Grey=2, Black=4 |
| Debris | Low=0, Medium=1, High=2 |
| Structure criticality | Residential=0, Commercial=1, Industrial=2, Critical=3 |
| Utilities impacted | No=0, Yes=2 |
| Basement / below-grade | No=0, Yes=1 |
- 0–6 → Class 1 (Minor)
- 7–12 → Class 2 (Moderate)
- 13–18 → Class 3 (Severe)
- 19–24 → Class 4 (Extreme)
- Measure average depth and note whether water is moving.
- Estimate how long materials were wet before control.
- Select contamination, debris, and site criticality accurately.
- Mark utilities impacted if panels, wiring, or HVAC are wet.
- Submit to get class, score breakdown, and action guidance.
- Export CSV/PDF to attach to reports or bid packages.
Input quality and site survey
Accurate classification begins with a consistent survey. Measure average depth across the affected footprint, not the deepest point. Note whether water is moving, because velocity drives impact forces, scouring, and debris transport. Record exposure duration from first wetting to active control. These three inputs stabilize the risk score and make comparisons repeatable across crews and days.
Contamination and debris implications
Contamination changes the restoration pathway. Clean water may allow drying and selective removal, while grey water increases cleaning and disinfection requirements. Black water conditions typically demand controlled access, disposal protocols, and professional sanitation. Debris load affects pumping efficiency, equipment selection, and slip and trip hazards, which can increase downtime and labor allowances.
Operational planning for construction teams
The class output supports early sequencing decisions. Lower classes usually prioritize extraction, ventilation, and localized repairs. Higher classes often require containment, demolition planning for saturated porous materials, and staged drying with moisture verification. Using a point breakdown helps justify scope, select PPE levels, and coordinate trades for electrical, HVAC, and finish restoration. For example, shallow standing water under 10 cm often scores minimal depth points, while depths above 120 cm trigger the highest tier. Pair velocity with depth when evaluating stability near openings, pits, and trenches. Use area estimates to communicate pumping hours and staging early.
Documenting results for cost and compliance
Exported summaries improve handoffs between supervisors, insurers, and subcontractors. A structured record of depth, velocity, duration, and contamination supports bid notes and change documentation. The score breakdown provides an auditable rationale for equipment hours and drying windows. Keep time-stamped photos, moisture logs, and disposal tickets aligned to the class determination.
Limitations and verification steps
This calculator uses a transparent scoring method for rapid triage. It does not replace engineering review, local regulations, or moisture mapping. Confirm safety with lockout procedures, structural inspection, and air quality checks where needed. Recalculate after pumping or demolition, because reduced depth and duration can shift the class and refine the plan.
1) What does “Flood Water Class” mean in this tool?
It is a practical severity label based on measurable conditions. The calculator converts depth, velocity, duration, and site factors into a risk score, then maps that score to Class 1 through Class 4 for consistent field triage.
2) Is the class the same as a regulatory flood zone?
No. Regulatory flood zones describe probability and mapping. This tool classifies current on-site impacts and restoration complexity. Use it for response planning, documentation, and estimating, not for permitting or long-term zoning decisions.
3) How should I estimate velocity if I do not have instruments?
Use a conservative estimate. Standing water is near 0. For moving flow, observe floating debris travel distance over time. If unsure, select a higher range to avoid under-classifying hazards and to plan safer access and controls.
4) Why does contamination change the score so much?
Contamination drives PPE, cleaning, disposal, and verification requirements. Grey and black water typically increase labor, equipment, and downtime. The higher points help signal when specialized sanitation and controlled access are likely needed.
5) Can I use this for basements, pits, or below-grade structures?
Yes. Select “Basement / below-grade” to reflect trapped moisture and reduced drying efficiency. Still confirm ventilation, electrical isolation, and structural condition before entry, because confined areas can elevate safety risk.
6) How often should I recalculate during a project?
Recalculate after major changes: pumping completion, demolition of wet finishes, or improved containment. Updated depth and duration can reduce the score and refine equipment needs. Keep prior exports to show how conditions improved over time.