City of Portsmouth — Bathing Water Quality 2025

Bathing water sites in City of Portsmouth

City of Portsmouth bathing water — FAQ

Is the sea water quality good in City of Portsmouth?

City of Portsmouth has a Gera Bathing Water Score of 60/100 (0 of 2 rated sites Excellent, 1 Poor) for the 2025 season. A GBWS of 60 reflects a combination of current classification (weighted 60%) and multi-season consistency across all assessed seasons, up to six from 2019–2025 (weighted 40%). This score is below the national average, suggesting some sites have water quality concerns.

What does the Gera Bathing Water Score mean?

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.

How are City of Portsmouth bathing waters classified?

The Environment Agency classifies each designated bathing water under the Revised Bathing Water Directive (rBWD): Excellent, Good, Sufficient, or Poor, based on 4 seasons of E. coli and intestinal enterococci samples. City of Portsmouth has 2 designated site(s). Annual classifications are published on the EA's Bathing Water Quality platform.

When is the bathing season?

The official bathing season in England runs from mid-May to the end of September each year. The EA monitors water quality weekly during the season. Outside the season, monitoring is not required and advisories may not be current.