Research and analysis

Faecal contamination: challenges for the water environment

Updated 16 March 2026

Applies to England

1. Background

1.1 Relevance and accuracy of data

This document has been produced by bringing together the readily available information on the topic. Quality assurance of the information included so far is not complete. As a result, the document may contain some errors or inaccuracies. Let us know of any other relevant evidence or if you are aware of any issues with the information. This will help us to build a comprehensive and robust evidence base to underpin decision making in river basin management planning.

2. The problem

Faecal bacteria are an important factor to consider when protecting the environment to safeguard public health, particularly preventing ingestion of contaminated shellfish or water whilst swimming.

Faecal contamination has been identified as a significant issue for river basin planning because of its inclusion in ‘Protected Area’ objectives for bathing, shellfish and drinking waters.

2.1 Evidence for the problem

2.1.1 Bathing waters

In 2025, overall compliance remained high and slightly improved compared to 2024, with 417 (92.9%) bathing waters meeting the minimum standards compared to 413 (91.8%) in 2024. This is the largest number of compliant waters since 2015 when the standards were introduced.

In 2025, 87.3% of bathing waters in England were rated as ‘good’ or ‘excellent’, continuing to show an overall boost in water quality over recent decades. This compares to just 28% being rated as ‘good’ or ‘excellent’ in the 1990s.

In 2024, the largest number of new sites ever were designated in a single year (27 sites), including 12 rivers. This reflects the growing interest in recreational water use. Following these designations, the 2024 classifications saw the number of ‘poor’ waters increase to 37 (8.2%) compared to 18 (4.3%) in 2023. This increase in ‘poor’ waters is mainly due to the increase in new bathing water designations.

It is not unexpected for a newly designated site to be ‘poor’, as up until that point they would not have been monitored or managed for bathing. In addition, rivers face a greater challenge to meet bathing standards than coastal locations. Rivers often have poorer bathing water quality compared to the sea, which benefits from the natural disinfection of salt-water as well as high levels of dispersion of any pollutants. 

Figure 1 shows the bathing water classifications from 2019 to 2025 for England. Since 2019, the percentage of water bodies with an ‘excellent’ classification have decreased from 72% to 66.1%, whilst water bodies with a ‘good’ classification remains at 21%. Water bodies with ‘sufficient’ or ‘poor’ status have increased from 5% to 5.6%, and 1.7% to 7.1% respectively. Table 1 shows that the total number of bathing water designations has increased from 421 in 2019 to 451 in 2025. This increase is likely the main cause of the increase in water bodies with ‘sufficient’ or ‘poor’ status.

There were no classifications produced in 2020 due to the COVID-19 pandemic.

Figure 1: Percentage of designated waters according to classification 2019 to 2025

Bathing water body numbers	‘Excellent’ classification	‘Good’ classification	‘Sufficient’ classification	‘Poor’ classification
2019	71.90%	21.40%	5.00%	1.70%
2021	70.70%	24.00%	4.30%	1.00%
2022	72.10%	20.80%	4.30%	2.90%
2023	66.40%	23.40%	5.90%	4.30%
2024	64.20%	21.10%	6.40%	8.20%
2025	66.10%	21.20%	5.60%	7.10%

Table 1: Bathing water body numbers from 2019 to 2025

	2019	2021	2022	2023	2024	2025
Number of unclassified sites	1	2	2	1	1	2
Number of designated bathing waters	421	419	421	424	451	451

In addition to the 32 bathing waters that were classified as ‘poor’ in 2025 there are a further 22 bathing waters that are ‘at risk’ of becoming ‘poor’.

The Environment Agency also monitors to work out whether any bathing waters have deteriorated in quality. There are 83 bathing waters that have shown deterioration. These waters are prioritised for investigation to determine the sources of pollution and the required measures to improve their quality.

2.1.2 Shellfish waters

There are 101 designated shellfish waters in England. Compliance with the shellfish water microbial standard in 2024 was 23%. This was similar to that recorded in 2023 (29%), 2022 (35%) and 2021 (25%). The lower compliance in shellfish waters is a reflection of:

• the fact that shellfish are filter feeders which accumulate and thrive on faecal bacteria
• the very tight microbial standard in the Shellfish Directions

Research has shown that to consistently achieve the microbial standard of less than 300 Escherichia coli (known as E. coli) per 100g of shellfish flesh, the water column must contain fewer than 5 E. coli per 100ml. In comparison, the ‘excellent’ classification of the Bathing Water Regulations requires the 95 percentile of water column samples to be less than 250 E. coli per 100ml.

As with bathing waters, the Environment Agency assesses where any shellfish water has deteriorated over recent years. Assessing deterioration in shellfish waters is more difficult due to:

• the relatively small number of samples taken each year
• monitoring points moving frequently to reflect where shellfish are currently being harvested – long term datasets (which are required to identify trends with confidence) are rare
• the lack of a clear and consistent relationship between shellfish flesh quality and water quality

A statistical method has been developed to identify the waters at greatest risk of deterioration. This is used with other information to understand where deterioration has occurred. This is called a weight of evidence approach. In 2024, analysis indicated that approximately half of shellfish waters needed further assessment to determine whether deterioration was likely.

2.1.3 Drinking Waters

Drinking Water Protected Areas (DrWPAs) are designated by the Environment Agency under Article 8 of the Water Environment Regulations 2017 (Water Framework Directive) (England and Wales). DrWPAs are water bodies such as rivers, lakes and groundwater that currently supply, or are expected to supply, more than 10 cubic metres of water per day for human consumption or serve over 50 individuals.

The objectives for DrWPAs are:

• to ensure the necessary protection of the supply by avoiding deterioration in water quality to reduce the level of purification treatment required in producing drinking water
• for groundwater, to meet good chemical status and reverse upward trends in pollution
• to identify measures to reduce the level of purification treatment required in the production of drinking water abstracted from it, with the aim of avoiding deterioration in the water quality in that area

Where a DrWPA is ‘at risk’, a non-statutory safeguard zone (SgZ) is established. This identifies the catchment area where land use practices are most likely to be causing, or have caused, water quality in the DrWPA to deteriorate. SgZs focus pollution prevention and regulatory actions where they are most needed.

Cryptosporidium is a protozoan parasite found in water contaminated by both human and animal wastes. Catchment sources include sewage works, farms, soil run-off, drainage and livestock using or crossing watercourses. The Drinking Water Regulations include standards for the safety of drinking water. The safe limit for cryptosporidium and faecal indicator organisms at the tap is zero. The Drinking Water Inspectorate is responsible for the ‘wholesomeness’ of water under these regulations.

DrWPA are no longer designated for faecal organisms or indicator organisms as this is managed by DWI under ‘wholesomeness’. However, they can be designated as ‘at risk’ for substances such as sediment, nutrients and algae. The work to reduce sediment, nutrients and improve drainage will contribute to compliance with the standards for faecal organisms.

For more information on DrWPAs, see DrWPAs: challenges for the water environment.

2.2 Sources of faecal bacteria and reasons for failure

Bathing and shellfish water quality is affected by a range of sources. The most important sources are:

• agricultural diffuse pollution
• sewage related pollution
• urban diffuse pollution (including contamination from dogs and birds)

The relative contribution from these sources will vary between sites depending on the nature of the catchment and its land use. Most sites are affected by more than one source.

2.2.1 Bathing waters

Following the 2025 bathing season, 54 bathing waters are currently ‘poor’ or are at risk of being ‘poor’. The source of the faecal bacteria at these bathing waters is from several sources, including:

• agricultural sources – contributing more than 10% of the total contamination at 32 waters
• sewage – contributing more than 10% of the total contamination at 47 waters
• other sources (including urban runoff, dogs and birds) – contributing more than 10% of the total contamination at 35 waters

2.2.2 Shellfish waters

Of the shellfish waters that do not consistently achieve the Shellfish Directions microbial standard, the 2 main sources of contamination are the water industry and agricultural sectors. Their contributions are as follows:

• sewage contributes more than 10% of the total contamination at 76 waters
• agricultural sources contribute more than 10% of the total contamination at 49 waters

2.2.3 Protected areas failing protected areas standards due to faecal contamination, by sector responsible

The numbers in Table 2 and Table 3 do not add up to the total number of non-compliant bathing or shellfish waters. This is because there is usually more than one reason for not achieving the relevant standard at any individual protected area.

Table 2: Number of shellfish waters protected areas failing protected areas standards due to faecal contamination (where source contributes greater than 10% of the faecal contamination) 

Source	Number of protected areas failing standards
Other (point source)	11
Urban (diffuse source)	25
Animals or birds (diffuse source)	36
Agriculture (diffuse source)	49
Water company (point source)	76

Table 3: Number of bathing water protected areas failing protected areas standards due to faecal contamination (where source contributes greater than 10% of the faecal contamination)

Source	Number of protected areas failing standards
Agricultural sources	32
Sewage	47
Other sources including urban, dogs and birds	35

2.3 Risk of deterioration

The water environment is already under considerable pressure from a range of human activities and a growing population. In the longer term, bathing and shellfish waters are at risk of deterioration due to these pressures. Climate change adds to this pressure.

Our climate is changing and this is set to continue. The UK Climate Projections 2018 (UKCP18) predict that hotter drier summers, milder wetter winters, rising sea levels and more extreme weather events are expected.

Climate change has a range of water quality impacts, including changes to river flow, groundwater recharge and water temperatures. Rainfall patterns will change and winter rainfall will occur in heavy events whilst summer rainfall will decrease. The trend of more intense rainfall events is expected to continue.

Increased periods of heavy rainfall:

• can significantly impact bathing and shellfish waters as they can result in more frequent operation of sewer overflows
• is more likely to wash pollutants from agricultural and urban land into rivers, groundwater and the sea
• increases the total amount of sewage (the rain means there is a greater volume of more dilute sewage) and puts further pressure on sewerage systems and the environment

However, drier and hotter summers may be beneficial for bathing and shellfish waters. This is because bacteria are killed off more quickly when there is increased sunlight and there could be fewer combined sewer overflow discharges.

Adaptation to climate change is key. For example, farmers and land managers have a responsibility to minimise agriculture and chemical runoff resulting from heavier rainfall events by adapting their land management practices.

2.4 Evidence gaps

Most of the bathing and shellfish waters with problems are affected by multiple diffuse sources of faecal contamination. The main evidence gap is confirming the source of the faecal bacteria, which is very challenging due to:

• the multitude of potential pathways and sources
• the varying decay rates of different pathogens under different weather conditions
• the intensity and cost of monitoring that is required

Another potential evidence gap may exist in the use of the generic faecal indicator organism (E. coli) when the actual health risk could differ between sources.

The Environment Agency does not routinely monitor DrWPAs (for surface water and groundwater) for bacterial contamination. Water companies must monitor their supplies and alert the Drinking Water Inspectorate if they detect an issue.

3. Current control measures

The Environment Agency take a catchment approach to identify actions to improve bathing and shellfish water quality. The most significant sources of bacterial pollution across the catchments of these protected areas are identified through modelling and investigations. The Environment Agency then focus actions to address these sources. We take an integrated approach to ensure that other measures to address other water quality problems in the catchment complement them.

3.1 Evidence for control measures

3.1.1 Water Industry

Water company measures were developed for 2020 to 2025 to tackle the contribution from water company assets. During this period, 26 event duration monitors were installed at bathing waters. Improvements were made to assets affecting 22 bathing waters and investigations were carried out at 104 bathing waters.

For shellfish waters:

• actions were taken at 20 water company assets
• investigations were conducted at 19 shellfish waters
• 214 event duration monitors were installed

From 2025 to 2030:

• more than 300 water company assets will be upgraded across 97 bathing water sites
• improvements will be made to over 100 assets at 33 shellfish waters
• 66 investigations at bathing waters and 39 investigations at shellfish waters will be conducted – the results of these shall improve our understanding of the impacts of water company operations

Ofwat has allowed for a £300 million increase in microbiological treatment costs due to new schemes added to reflect the designation of 27 additional bathing waters. Bathing waters actions represent an estimated £400 million in microbiological treatment costs due to new schemes and microbiological treatment improvements. This combines statutory compliance, no deterioration protection and voluntary enhancement schemes across both coastal and inland locations. This budget includes approximately:

• £70 to £80 million dedicated to microbiological treatment infrastructure (primarily ultra-violet disinfection and increased flow to full treatment capacity – FFT)
• £155.1 million for high frequency water quality monitoring and telemetry (for example sensor networks and real-time analysis)
• £30 to £40 million invested in investigations, modelling and support for inland bathing water designations

This continued investment builds on the approximately £2.5 billion and £140 million capital already invested by the water industry since privatisation to improve assets that discharge to bathing and shellfish waters respectively.

3.1.2 Agriculture

Incentives, advice and regulation are targeted where they will make the most difference and achieve real outcomes for the water environment. Protected areas such as bathing waters, shellfish waters and DrWPAs (including groundwater bodies) are prioritised.

The Environment Agency work with partners including:

• farming representatives
• catchment sensitive farming (CSF)
• forestry and wider agricultural supply chain sectors through the Catchment Based Approach (CaBA)
• local catchment partnerships

Their work aims to minimise local environmental impacts on the water environment. This includes minimising impacts on the services a healthy water environment provides such as drinking water, recreation, navigation and supporting wildlife.

The CSF programme (2006 to 2024) has delivered significant engagement in bathing water catchments. This resulted in 10,522 farms (5,903 since 2020) visited with mitigation measures advised which will reduce faecal indicator organism (FIO) concentrations. This equates to 61,871 (21,753 since 2020) specific measures to address FIO reductions.

The CSF programme (2006 to 2024) has also delivered significant engagement in shellfish water catchments. This has resulted in 6211 farms (3667 since 2020) visited with mitigation measures advised which will reduce FIO concentrations. This equates to 36,526 (13,355 since 2020) specific measures to address FIO reductions.

Mitigation measures advised through one-to-one CSF advice are estimated to have reduced agricultural loadings of nutrients, suspended sediment, pesticides and faecal contamination by between 4% and 12% on average.

Countryside Stewardship (CS) funding (2016 to 2024) has paid for 68,600 agreement options (56,541 since 2020). This will reduce FIO concentrations in bathing water catchments, equating to 18,385 farms with CS agreements (16,719 since 2020) across all bathing waters.

CS funding has also paid for 23,094 agreement options (17,221 since 2020) which will reduce FIO concentrations in shellfish catchments. This equates to 11,981 farms with CS agreements (10,876 since 2020) across all shellfish waters.

Sustainable Farming Initiative (SFI) funding (2023 to 2024) has paid for 9,387 agreement options which will reduce FIO concentrations in bathing water catchments. This equates to 6746 farms with SFI agreements across all bathing waters.

SFI funding has also paid for 6,289 agreement options which will reduce FIO concentrations in shellfish catchments. This equates to 4430 farms with SFI agreements across all shellfish waters.

This work has delivered improved infrastructure addressing both sources and their pathways. It is underpinned by advice from both CSF officers and specialist contractors on livestock management, soil husbandry, manure management and water management, all of which contribute to reduced faecal pollution.

3.1.3 Urban diffuse pollution

Bathing and shellfish waters are often affected by localised diffuse sources of faecal contamination from urban and highway drainage. In addition, uncontaminated surface water runoff can become contaminated by misconnected drains from households and businesses as well as background faecal contamination from birds, wildlife and pets.

Joint working between local authorities, water companies and the Environment Agency has been successful in many cases in identifying and remediating these misconnections. Where surface water drainage can reach bathing waters, the risk from faecal contamination will be present. Long-term partnerships are likely to be the only effective way to mitigate this risk.

3.2 Control measures acting in combination with other pressures

The control measures, outlined in Section 3.1, reinforce the fact that bathing and shellfish waters alongside other surface and groundwaters are affected by pollution from multiple diffuse sources.

Pollution arising from agricultural activities may require remedial measures to be applied to many farms. Agricultural measures may result in multiple benefits in addition to lowering levels of faecal contamination, such as lowering:

• sediment loading
• nutrient run off (nitrogen and phosphorus)
• contamination from other substances (such as pesticides, ammonia and increasing dissolved oxygen levels)

Bathing and shellfish water sites with significant urban contamination is mainly due to misconnections and highway drainage to urban streams. Urban control measures may also result in multiple benefits in these catchments, such as a decrease in domestic or industrial levels of phosphorus and a variety of other chemical pollutants.

3.3 Whether current control measures are sufficient to achieve our objectives

3.3.1 Faecal bacteria standards (targets) and their application

The Environment Agency continues to work with partners to tackle the sources of pollution at:

• bathing waters that are classified as ‘poor’, at risk of becoming ‘poor’ or have shown deterioration
• shellfish waters that do not consistently comply with the Shellfish Directions microbial standard or have shown deterioration

The greatest challenge the Environment Agency face in further raising compliance and ensuring we maintain the quality achieved is being able to meaningfully tackle sources of urban and agricultural diffuse pollution. While sewage from water company assets currently remains a risk to compliance, targeted water company investment will continue in future investment periods and this risk will continually decrease.

Increasing compliance is particularly challenging at shellfish waters, most of which are in estuaries, where sewage from dense coastal populations, urban runoff and agricultural runoff can create high levels of faecal pollution. The effect is particularly pronounced in the west of the country, where rainfall is heavier, resulting in more pollution from intermittent sewage overflows and runoff.

3.2.2 Evidence gaps

The main evidence gap regarding current control measures is identifying where the faecal bacteria are coming from. This is very difficult as there are many potential pathways and sources, and each protected area has a unique combination of inputs. More monitoring of faecal bacteria in the catchments of shellfish waters and ‘at risk’ bathing waters would help fill this gap. This monitoring would involve taking water samples from rivers in the catchment and analysing them for faecal bacteria.

There is currently no national, long term data set relating to the presence of faecal bacteria in catchments or rivers. Although, with the recent designation of more river bathing water sites, our understanding of water quality at these sites will begin to grow.

A national bathing water group is working to bring stakeholders together including water companies, local authorities and non-governmental organisations with an interest in bathing waters. The group works to provide a common understanding of the issues facing bathing waters and how these can be addressed.

4. Other considerations: opportunities and risks

The 25 Year Environment Plan recognises the importance of bathing water quality and commits to “minimising by 2030 the harmful bacteria in our designated bathing waters and continuing to improve the cleanliness of our waters. We will make sure that potential bathers are warned of any short-term pollution risks”.

In England, recreational bathing activity has traditionally occurred at coastal sites. However, anecdotal evidence suggests that bathing practice is changing, particularly in relation to the increasing popularity of “wild swimming” and sporting events including triathlons. The designation of river bathing water sites for the first time in recent years, reflects this.

Of the total 451 designated waters in England:

• 419 are coastal
• 18 are inland lake sites
• 14 are river sites

Rivers and other open water locations that are not designated as bathing waters are managed for the purpose of protecting fish and wildlife, not people. Health risks from using these locations may be higher than at designated bathing waters. Applications for sites which are attracting many bathers to be designated as bathing waters can be made to the Department for Environment, Food & Rural Affairs (Defra) under the Bathing Water Regulations 2013. For more information, see Bathing Waters: apply for designation or de-designation.

Shellfish waters are recognised in the commitment to achieve “good environmental status in our seas while allowing marine industries to thrive”.

However, there is a conflict between using energy to treat water to improve its quality and the resulting emissions of greenhouse gases. There is a perceived reliance on high energy treatment solutions such as UV treatment to support protected area targets. We need to balance the impacts associated with improving individual protected areas with the wider impacts on the environment.

5. References

Bathing Waters: working in partnership in England and Wales, Environment Agency, October 2010.