A citizen water map for Ireland

This is a modelled estimate of the chance that bacterial levels exceed the EU bathing limits. It is not a test result, not an official rating, and not advice on whether to swim. The official EPA or DAERA classification is shown alongside it and always takes precedence. For water-safety guidance see Water Safety Ireland.

Official bathing samples are taken roughly fortnightly in season, so on any given day the newest result may be days or weeks old. WaterWatch trains a model on the full history of EPA and DAERA bacterial samples plus recent rainfall, distance to the nearest storm-water outfall, and the land around each site, and estimates the chance that today exceeds the EU limits. It is an estimate, shown with its confidence and what drove it, and always beside the official classification, which is the statutory answer and always takes precedence.

• Estimates come from the current WaterWatch v2 model, one pooled model covering every site rather than a separate model per beach. The exact model version behind any estimate is returned by the API, and the validation figures sit with the project decision records.
• It is a model, so it can be wrong in both directions. It is shown with a confidence level, and lower confidence means exactly that.
• It never replaces or contradicts the official EPA or DAERA classification, which is displayed alongside every estimate.
• Some beaches show no estimate at all. WaterWatch only shows one where the model is in coverage for the spot (a mapped, designated bathing water) and its recent live checks are passing, so a data-poor, unmapped or brand-new spot reads "not available yet" rather than a guess. Absence never means the water is fine.
• Estimates are scored against the official samples as they arrive. If the model stops beating the simple baseline it is withdrawn and refreshed, so a drifting model goes quiet rather than staying wrong.
• Where it does flag a higher chance, it is tuned to a balance between catching real contamination and not raising too many false alarms, checked against published bathing-nowcast benchmarks. It will still miss some events and flag some clean days.
• Ireland publishes no live sewage-overflow data, which is the single strongest predictor of contamination. The model cannot see spills, only their proxies.
• It says nothing about currents, waves, tides or cold water. For those, and for whether to enter the water at all, follow Water Safety Ireland.

Estimates are trained on EPA bathing-water sample data © Environmental Protection Agency (CC-BY-4.0), Northern Ireland bathing-water sample data © Crown copyright, Department of Agriculture, Environment and Rural Affairs (containing public sector information licensed under the Open Government Licence v3.0), and rainfall data from Met Éireann (CC-BY-4.0) and Open-Meteo (CC-BY-4.0). Met Éireann accepts no liability for the rainfall data or its use.