How bathing water is classified: the EU thresholds explained
Every EU bathing water gets one of four classes — Excellent, Good, Sufficient or Poor — by comparing percentile values of two faecal-indicator bacteria, Escherichia coli and intestinal enterococci, with fixed limits in Annex I of Directive 2006/7/EC. Coastal and inland waters have different limits.
The limits behind each class
Values are colony-forming units (cfu) per 100 ml. “95th” and “90th” mean the percentile of the sampling results that must not exceed the limit.
| Indicator | Excellent | Good | Sufficient |
|---|---|---|---|
| Intestinal enterococci | 100 (95th) | 200 (95th) | 185 (90th) |
| E. coli | 250 (95th) | 500 (95th) | 500 (90th) |
| Indicator | Excellent | Good | Sufficient |
|---|---|---|---|
| Intestinal enterococci | 200 (95th) | 400 (95th) | 330 (90th) |
| E. coli | 500 (95th) | 1,000 (95th) | 900 (90th) |
A site is Poor when it fails the Sufficient limits. The Sufficient class uses the more lenient 90th percentile, which is why its enterococci limit can look lower than the Good limit: it is applied to a different point of the distribution.
How the assessment works
- Several seasons, not one sample. The class is normally based on the results of the last four bathing seasons, with a data set of at least 16 samples (fewer only where the season is very short).
- Sampling during the season. At least four samples are taken per season — one shortly before it starts — at intervals of no more than a month (three samples are allowed for very short seasons or remote locations).
- Percentiles on log values. The percentiles are calculated from the logarithms of the bacterial counts (Annex II of the Directive), so a single very high result does not dominate, but repeated high results do.
- Short-term pollution. Samples taken during a recognised short-term pollution event can, under conditions set in the Directive, be disregarded and replaced by a follow-up sample — another reason the annual class can differ from what bathers saw on a bad day.
What each class means in practice
- Sufficient is the legal minimum
- EU countries must ensure bathing waters are at least Sufficient and take measures to raise the number of Excellent and Good sites.
- Poor triggers management measures
- For a Poor site the authority must take measures, including a bathing prohibition or advice against bathing, inform the public and work on the causes of pollution. After five consecutive Poor classifications, a permanent bathing prohibition or permanent advice against bathing is required.
- Not classified is not a verdict
- It usually means there were not enough valid samples, or the site is new or has changed. Of the 617 sites without a 2025 class in the EEA data, 286 had a classified season at some point since 2015.
What the 2025 data look like
Applying these rules, the EEA 2025 dataset contains 22,289 bathing waters. Coastal and transitional sites reach Excellent more often than lakes and rivers, which receive more run-off from farmland and towns and have less dilution.
| Group | Sites | Excellent | Good | Sufficient | Poor | Not classified |
|---|---|---|---|---|---|---|
| Coastal and transitional | 14,861 | 87.4% | 7.7% | 2% | 1.1% | 1.7% |
| Inland (lakes, rivers) | 7,428 | 78.3% | 11.3% | 2.9% | 2.7% | 4.8% |
| All bathing waters | 22,289 | 84.4% | 8.9% | 2.3% | 1.6% | 2.8% |
61 sites were classified Poor in each of the five seasons 2021–2025 — the situation in which the Directive requires a permanent prohibition or advice against bathing: POGRADEC (Albania), POGRADEC (Albania), DURRES (Albania), VLORE (Albania), POGRADEC (Albania), DURRES (Albania), VLORE (Albania), RAEKÜLA RAND (Estonia) and 53 more.
What the classes do not measure
The classification covers microbiological contamination only. It says nothing about cyanobacteria (blue-green algae) blooms, jellyfish, currents, water temperature, litter or chemical pollution, which authorities monitor and announce separately. That is why every site page here links to the national authority, and why an Excellent class is long-term context rather than today’s permission to swim.
Sources
- Directive 2006/7/EC concerning the management of bathing water quality (EUR-Lex) — Articles 4 and 5, Annexes I, II and IV.
- European bathing water quality in 2025 (EEA) — the assessment behind the classes on this site.