Porthallow — Bathing Water Quality 2025

Classification history

2020 excluded (COVID-19 cancelled the bathing season). Source: EA BWQ API.

Porthallow — FAQ

Is Porthallow safe to swim?

Porthallow is rated Excellent for the 2025 bathing season — the highest EA rBWD classification, indicating consistently good water quality. It is safe to swim under normal conditions. Always check the EA for real-time advisories after heavy rainfall.

What does Excellent classification mean?

Excellent is the highest EA rBWD classification. It means the site consistently meets the strictest water quality thresholds for E. coli and intestinal enterococci across multiple seasons. It is the equivalent of a "Blue Flag" water quality standard.

What is the Gera Bathing Water Score?

The Gera Bathing Water Score (GBWS) combines two components from Environment Agency rBWD annual compliance classifications (key-free open data, OGL v3.0): (1) latest classification score (Excellent=100, Good=75, Sufficient=50, Poor=25), weighted 0.6; and (2) pass-rate across every assessed season available for the site (up to six: 2019, 2021–2025; the proportion rated Sufficient or above), weighted 0.4. Formula: GBWS = round(0.6 × latest_score + 0.4 × pass_rate × 100). Sites with fewer than 3 assessed seasons are shown as 'insufficient data'. The 2020 bathing season was cancelled due to COVID-19 and is excluded. LA-level scores are the mean GBWS of all sites within the LA that have sufficient data. Source: EA BWQ API, seasons 2019, 2021–2025.

Who monitors Porthallow?

Porthallow is a designated bathing water in Cornwall, monitored by the Environment Agency. It is a coastal bathing water. The EA takes regular water samples during the bathing season (May–September) and publishes weekly results at environment.data.gov.uk/bwq/. The annual classification is published after the season closes.