Inputs
Fill values as known. Use conservative estimates when unsure.
Example Data Table
| Scenario | Source | Hazard Distance (m) | Flood | Controls | Typical Risk |
|---|---|---|---|---|---|
| Urban building site | Municipal supply | 120 | Low | Backflow + filtration + monthly testing | Low to Moderate |
| Remote roadworks | Tanker delivery | 40 | Medium | Covered storage + weekly testing | Moderate to High |
| Riverside excavation | Surface water | 20 | High | Filtration + disinfection + weekly testing | High |
Examples are illustrative. Local standards and testing results should guide decisions.
Formula Used
This calculator produces a 0–100 index from weighted factors.
| Symbol | Factor | Range (points) |
|---|---|---|
| A | Source vulnerability by type | 0–25 |
| B | Distance exposure (scaled to 200 m) | 0–10 |
| C | Hazard proximity (closer = higher) | 1–15 |
| D | Flood exposure category | 3–15 |
| E | Water quality points (turbidity + TDS + chlorine) | 0–15 |
| F | Incident history | 0–5 |
| G | Rain intensity | 1–5 |
| H | Demand severity | 0–5 |
| I | Duration severity | 0–5 |
| Mit | Mitigation credits from controls | 0–20 |
Raw points: Raw = A + B + C + D + E + F + G + H + I − Mit
Risk Index: Index = (Raw / 100) × 100 (clamped to 0–100)
Weights can be adjusted to match project standards and local conditions.
How to Use This Calculator
- Pick the water source type you plan to use.
- Enter distances to the use point and hazards.
- Select the flood exposure level for the work zone.
- Enter any available quality readings and site data.
- Tick controls you already have in place.
- Press Calculate Risk to view results above.
- Download CSV or PDF for records and reporting.
Water sources and construction exposure pathways
On active sites, water travels through temporary hoses, tanks, and standpipes. Each transfer point increases leak probability and cross-connection risk. Long runs across traffic zones add mechanical damage exposure and unobserved losses. When supply is trucked or harvested, refilling events introduce new handling steps and potential contamination.
Interpreting the risk index for decisions
The index converts weighted factors into a single score from 0 to 100. Lower scores support routine controls, while higher scores indicate a higher likelihood of interruption or contamination. Use the level to prioritize inspections, treatment, and standby storage. Track the score by phase so managers can see whether risk rises during peak demand. For tendering, include the score and planned mitigations in method statements to justify temporary works and monitoring budgets during rainy seasons.
Quality indicators that matter on site
Turbidity is a quick signal of suspended solids that can clog filters and affect finishes. TDS reflects dissolved minerals that can cause scaling in heaters, pumps, and spray nozzles. Residual disinfectant outside a typical band may indicate under-treatment or overdosing and should trigger verification testing. Record readings with the date, sample point, and weather conditions for better trend interpretation.
Environmental and operational stressors
Flood exposure and heavy rainfall increase runoff, backflow, and infiltration pathways, especially near excavations or storage areas. Proximity to fuel bays, septic systems, and chemical laydown zones raises consequence if a spill occurs. Incident history captures patterns like repeated leaks, low pressure, or past contamination notices. Demand and project duration raise consequence because more activities depend on water availability for curing, dust control, cleaning, and worker welfare.
Using controls to reduce measurable risk
Mitigation credits reward practical barriers like backflow prevention, sealed storage, filtration, disinfection, and scheduled testing. Combine controls with housekeeping: protect hoses, label connections, separate chemical storage, and use secondary containment for tanks. Assign owners for checks, document corrective actions, and recalibrate after improvements. Recalculate after changes to confirm reduction and communicate progress to stakeholders.
FAQs
What does a high risk index mean for a project?
It signals a higher chance of supply interruption or contamination. Increase testing frequency, add treatment, improve containment, and prepare an alternate source or stored volume before critical activities.
Which inputs influence the score the most?
Source type, hazard proximity, flood exposure, and mitigation controls typically shift the index strongly. Poor quality readings and repeated incidents also raise the score and should be investigated.
How should I estimate hazard distance on a busy site?
Measure the closest route between the water line or tank and any fuel, chemical, septic, waste, or washout area. Use the shortest realistic distance, including temporary relocations.
Do I need laboratory testing to use this tool?
No. The calculator works with estimates and simple field readings. Laboratory tests improve confidence, especially when the index is Moderate or higher, or when water affects concrete, finishes, or welfare.
How do controls reduce the score?
Selected controls earn mitigation credits that subtract from raw points, up to a cap. The intent is to reward practical barriers like backflow prevention, filtration, disinfection, sealed storage, and scheduled testing.
How often should I recalculate the risk?
Recalculate when the source changes, weather shifts, demand increases, or incidents occur. A monthly review is common, and weekly checks are useful during high rainfall or major pours.