All you need to know about bathing water quality

The perfect weather for a seaside trip or day out at a river or lake can’t always be guaranteed, but that usually doesn’t stop people from enjoying the many beautiful blue spaces the UK has to offer.

With the upsurge in open-water swimming particularly over the last year, more people than ever are using blue spaces for recreational activities and improving their health and wellbeing.

If you enjoy open-water swimming or want to take it up, information about bathing water quality around the UK can be found on the website.

To find out more about what bathing water quality is, why it’s important and how the weather can affect it, read more in this article from the Environment Agency.

Bathing waters in England and how they’re monitored

While the standard of bathing water quality in England is very high, the weather can have a temporary impact on the level of water quality. Knowing more about it, can really help you plan your trip to one of many beautiful blue spaces and get the most out of it.

The bathing water season in England runs from 15 May to the end of September. This is the time when most people are expected to use open waters and during the summer the water quality of over 400 designated bathing waters will be monitored so people can check the quality before swimming, paddling or splashing about.

Most designated bathing waters in England are on the coast, but there are a handful of inland lakes and this year, a newly designated area of river in Yorkshire. Being designated means that they’re monitored and protected from sources of pollution that are known to be a risk to bathers’ health.

Waters that are not designated are managed for the purpose of protecting fish and wildlife, so the health risks of swimming in these may be greater.

Around 7,000 samples will be collected over a bathing water season – and they’re taken come rain or shine. Once taken, each one is sent off to the Environment Agency’s specialist laboratory and tested for two types of bacteria; E coli and intestinal enterococci. These bacteria can come from many sources of pollution including sewage, agricultural livestock, wildlife, birds and road drainage.


The amount of bacteria found in the water is used to determine the standard of water quality and this is used to give each bathing water a classification. The standard of bathing water quality in England is very high with over 93% of bathing waters rated the highest standards of Good and Excellent. The Environment Agency produces a profile for each designated bathing water displaying the latest classification. Profiles provide lots of useful information about the bathing water and can help people decide on where to go. You can check these out on the Environment Agency’s Swimfo website. Classifications are also displayed on signs at beaches.

Look out for the four classifications of bathing water quality:

  • Excellent         – the highest, cleanest water quality
  • Good               – generally good water quality
  • Sufficient         – the water meets the minimum standard
  • Poor                – the water has not met the minimum standard

Know before you go – pollution risk forecasting

When it rains more bacteria can be washed into rivers, lakes and the sea. The Environment Agency uses Met Office data to make pollution risk forecasts to work out when water quality might be temporarily reduced due to factors such as weather conditions. Most bathing waters have a consistently high standard of water quality, but at some it can go up and down – this is where forecasting works best.

When the forecasts highlight reduced water quality, pollution risk warnings will be issued and advice against bathing is displayed on Swimfo and also on signs at the beach.

Checking water quality information before you head off to coastal or inland waters means you can avoid the times and locations where water quality might be temporarily reduced – usually after a heavy downpour.


During the bathing season, between May and September, when it’s warmer and there’s more sunlight, algae can bloom in marine and freshwaters. There are many different types of algae, and while they are a natural part of the water environment, some types can be mistaken for sewage, particularly in coastal waters. And, in freshwaters, blue-green algal blooms can be toxic.

You can’t tell if an algal bloom in the sea, lake or river is toxic just by looking at it, so it’s safest to assume it is and avoid contact with the water or algae. 

Bathing water profiles on the Swimfo website provide information on whether a bathing water is affected by algae during the bathing season. You can also get further information on

Checking the weather forecast is a staple in many peoples’ daily routines particularly when planning a day out. As the weather can have a direct impact on some of our blue spaces, make checking the water quality part of your daily routine too and know before you go!