v1.0 · published method
Water Risk Methodology
Every score shown in Water Risk Register is produced by the same published rules. Nothing is a black box: each score is displayed alongside the factors that produced it, so a leaseholder, broker or administrator can see exactly why a flat or block sits where it does.
The Water Risk Score
A 0–100 measure of recorded water risk for a flat. Higher means more risk. It is calculated from the following factors:
- Incident frequency
- How many water incidents have been recorded for the flat in the last 24 and 60 months.
- Recency
- Recent incidents weigh more heavily than historic ones; a leak last month is not the same as one six years ago.
- Severity
- Minor, moderate, major and severe incidents are weighted differently, using the worst recorded severity in the last 36 months.
- Recurrence
- Repeat incidents from the same cause or source, or incidents flagged as recurring, add weight.
- Unresolved defects
- Open incidents, overdue actions and unresolved professional findings raise the score until they are closed out.
- Temporary repairs
- A temporary repair with no permanent fix recorded is treated as an outstanding risk.
- Professional findings
- High and critical findings from surveyors, plumbers and leak-detection specialists carry the greatest weight.
- Evidenced permanent repairs
- Completed permanent repairs with verified evidence reduce the score.
| Band | Range | Meaning |
|---|---|---|
| Low | 0–24 | Little or no evidence of water-related risk. |
| Moderate | 25–49 | Some water-related risk recorded. |
| High | 50–74 | Significant unresolved water-related risk. |
| Critical | 75–100 | Severe or repeated unresolved water-related risk. |
Data Confidence
A separate 0–100 measure of how complete and well-evidenced the underlying records are. It is deliberately kept apart from the risk score so that a thin record can never be mistaken for a clean one.
- Record completeness
- Whether incidents include cause, source, location, damage and dates.
- Professional coverage
- Whether reports exist from qualified parties for the incidents recorded.
- Repair evidence
- Whether repairs have supporting invoices, photographs or sign-off documents.
- Verification status
- Whether records have been verified by an administrator or independently confirmed.
- Recency of records
- Whether the register has been kept up to date.
Block-level scoring
A block score is not a simple average. The distribution of flat scores is weighted so that a small number of high-risk flats cannot be diluted by a large number of quiet ones, and unresolved findings affecting communal systems — risers, tanks, roofs and shared pipework — are added separately because they are a property-wide exposure. Blocks where only a small proportion of flats are represented on the register are shown with reduced confidence rather than a flattering score.
What the score does not claim
- It is not an insurance rating, premium calculation or underwriting decision.
- It is not a survey, and it does not replace professional inspection.
- It reflects only what has been recorded. Unrecorded water damage cannot be scored.
- A low Data Confidence is a warning about the evidence, not a reassurance about the risk.
Versioning
Scores are stamped with the methodology version in force when they were produced. When the method changes, the version number changes with it, and historic assessments keep the version they were calculated under. The current version is v1.0.