Methodology
How we turn raw data into a risk rating — and what it can and can't tell you. Risk model v0.3.
The risk rating
Each beach gets a guidance rating, recomputed continuously (live overflow status every ~15 minutes, a full data sweep daily):
- RED — High concern A storm overflow is actively or recently discharging within 5 km, or a recent official sample showed high bacteria.
- AMBER — Caution Recent rainfall (≥8 mm in 48h) or a recent overflow nearby — conditions that commonly precede pollution.
- GREEN — Lower concern No recent overflow, low rainfall and no high samples.
- GREY — Not enough data Insufficient nearby monitoring to rate.
Each input is shown on the beach page so you can see why a rating was given: active/recent overflows within 5 km, rainfall over the last 24–48h, the latest official bacteria sample, independent samples, and nearby citizen reports.
Why risk, not certainty
Event Duration Monitoring (EDM) tells us whether an overflow is active and for how long — but not the volume spilled, and monitors can record false positives. Tides, currents and time since a spill all affect what actually reaches the water. So Glanmor presents evidence-based guidance, never a guarantee that water is safe or unsafe. Always check official alerts and use your own judgement.
Illness pollution-correlation score
Illness reports get a transparent score out of 100 across pollution proximity, water-test support, rainfall, illness timing, medical support and corroboration. This is a collation aid only — correlation, never a determination of legal causation.
Data sources & update frequency
Full source list and licences are on the about page. In summary:
- Environment Agency bathing-water samples & classifications (Open Government Licence) — ~7 years history.
- South West Water WaterFit Live — live overflow status & precise spill events (~15-minute refresh).
- Rivers Trust EDM annual returns 2020–2025 — per-outfall spill counts/durations.
- Open-Meteo — rainfall & tide context. GDELT — news. POOPy/sewage-map — modelled downstream impact.
Known limitations
- EDM shows duration, not volume; false positives are possible.
- The 5 km radius is a heuristic — local geography, currents and tides vary.
- Citizen reports are unverified unless marked otherwise.
- Data can be delayed or incomplete; absence of a record is not proof nothing happened.
Risk model v0.3. Changes to the model are reflected here. See also the raw data.
Do not rely solely on this website for health decisions. Check official alerts and use your own judgement. Seek medical advice if you are unwell.