Dry spills

We expose the murky waters of ‘dry spills’, dragging potentially illegal practices to the surface.

In this section:

Dumping sewage when it’s dry?

Potentially illegal practices

Sewage overflows were designed and intended to be an ‘emergency release valve’ only to operate in ‘exceptional rainfall events’ to reduce pressure on the sewage system to avoid sewage backing up into our homes. The Urban Waste Water Treatment Regulations only permit sewage overflows to operate in ‘unusually heavy rainfall’. However, the government has admitted sewage overflows “are being used significantly beyond their original purpose”.29

Water companies are prohibited from making ‘dry spills’ from sewage overflows when there has been no rainfall. However, with water companies now allowed to self-report and with little clarity on what is classed an ‘extreme rainfall event’ it’s unclear just how many ‘dry spills’ are happening and how much sewage is potentially being illegally discharged. So, we’ve been investigating where there have been discharges but no significant rainfall to indicate where sewage overflows are being used when they shouldn’t be. We’ve collated rainfall data provided by the Met Office from over 150 locations across England and Wales and linked the 455 locations on our Safer Seas & River Service (SSRS) to the nearest available data source to determine rainfall. We’ve then looked at the sewage discharge notifications issued for each of these locations and if there had been any rainfall in the [2] days preceding the discharge notification. Where we had seen a discharge notification but no rainfall in the preceding [2] days, we have assumed this to be a ‘dry spill’.

Take a look at the map below to investigate where we have found water companies to be making ‘dry spills’ over the last year – that’s raw sewage entering our waterways when there has been no rain.

We’ve uncovered 143 ‘dry spills’ pouring raw sewage into our most popular surf and swim spots between 1st October 2021 and 30th September 2022. Of these,

92 were at locations classified as ‘excellent’ for water quality by the regulator.

What’s the damage?

Figure 9 shows ‘dry spills’ by month and water company. We can see Southern Water was the worst offender. They were responsible for an eye-watering 39 of the 58 ‘dry spills’ in October 2021 alone. This is just one month after the bathing season ended and at a time many people were still using the water.

Most bathers will consider avoiding the water after heavy rain, but our analysis shows that sewage is being discharged into our precious blue spaces even when there has been no rainfall, putting us and the environment at risk. What’s worse is that in dry conditions where there is less water, the pollution entering waterways is more concentrated, so the contamination risk from the infectious organisms present in these untreated discharges is even higher.

Figure 9

Total “dry spills” by water company and by month

About this chart

This chart shows both the number of ‘dry spills’ made in the last year for each water company and as a total for each month. A ‘dry spill’ happens when sewage has been discharged at a location that hasn’t had any rainfall for 2 days. Use the drop down to switch the view to see all ‘dry spills’ by month.

Source: SAS Safer Seas and River Service, Met Office Rainfall data (Oct 21 – Sept 22)


Southern Water is racking up the highest level of dry spills with 4x more than the second worst offender South West Water.

Figure 10

Total “Dry spills” by location

About this chart

This table shows the locations which recorded the most “dry spills” from 1st Oct 2021 – 30th Sept 2022. A ‘dry spill’ happens when sewage has been discharged at a location that hasn’t had any rainfall for 2 days. For each location, there is information on the water company responsible and the bathing water classification.

Rank Location Water Company Bathing Water
Number of
Dry Spills
1 Cowes Southern Water Excellent 7
2 Felpham Southern Water Good 7
3 Teignmouth Holcombe South West Water Excellent 5
4 Gurnard Southern Water Good 5
5 Southend Three Shells Anglian Water Excellent 4
6 Par Sands South West Water Sufficient 4
7 Bembridge Southern Water Excellent 4
8 Pagham Southern Water Excellent 4
9 Sandown Southern Water Excellent 4
10 Seagrove Southern Water Excellent 4
11 Shanklin Southern Water Excellent 4
12 Whitecliff Bay Southern Water Excellent 4
13 Yaverland Southern Water Excellent 4
14 Humberston Fitties Anglian Water Good 3
15 Shoebury East Anglian Water Excellent 3
16 Shoeburyness Anglian Water Excellent 3
17 Southend Jubilee Beach Anglian Water Good 3
18 Littlehampton Coastguards Southern Water Good 3
19 Shoreham Beach Southern Water Excellent 3
20 Scarborough North Bay Yorkshire water Excellent 1
21 Southend Thorpe Bay Anglian Water Excellent 2
22 Dawlish Coryton Cove South West Water Excellent 2
23 Goodrington South West Water Good 2
24 Hillhead Southern Water Good 2
25 Hove Lawn Southern Water Excellent 2
26 Hythe Southern Water Excellent 2
27 Lepe Southern Water Excellent 2
28 Sandgate Southern Water Excellent 2
29 Southwick Southern Water Excellent 2
30 Allonby United Utilities Good 2
31 Allonby South United Utilities Good 2
32 Cleethorpes Anglian Water Good 1
33 Leigh Bell Wharf Anglian Water Good 1
34 Seaton Carew North Northumbrian Water Good 1
35 Croyde Bay South West Water Good 1
36 Dawlish Town South West Water Good 1
37 Paignton Paignton Sands South West Water Good 1
38 Porthtowan South West Water Excellent 1
39 Shaldon South West Water Excellent 1
40 Sidmouth Town South West Water Excellent 1
41 Teignmouth Town South West Water Excellent 1
42 Torre Abbey South West Water Excellent 1
43 Bexhill Southern Water Sufficient 1
44 Colwell Bay Southern Water Excellent 1
45 Eastney Southern Water Excellent 1
46 Herne Bay Central Southern Water Good 1
47 Langstone Harbour Southern Water N/A 1
48 Lee-on-Solent Southern Water Excellent 1
49 Ryde Southern Water Excellent 1
50 Saltdean Southern Water Excellent 1
51 Seaford Southern Water Excellent 1
52 Southsea East Southern Water Excellent 1
53 St Leonards Southern Water Excellent 1
54 Stokes Bay Southern Water Excellent 1
55 Tankerton Southern Water Excellent 1
56 Totland Bay Southern Water Excellent 1
57 Ventnor Southern Water Excellent 1
58 Port Meadow Thames Water N/A 1
59 Blackpool South United Utilities Good 1
60 Haverigg United Utilities Good 1
61 Meols United Utilities Excellent 1
62 Morecambe North United Utilities Good 1
63 Moreton United Utilities Excellent 1
64 Southport United Utilities Good 1
65 St Annes United Utilities Good 1
66 St Annes North United Utilities Sufficient 1
67 Benllech Welsh Water Excellent 1
68 Broadhaven Beach Welsh Water Excellent 1
69 Newgale Beach Welsh Water Excellent 1
70 Newport North Welsh Water Excellent 1
71 River Dee – Upper Dee Lane Welsh Water N/A 1
72 Wisemans Bridge Welsh Water Excellent 1
73 Poole Harbour Rockley Sands Wessex Water Good 1

Source: SAS Safer Seas and River Service, Met Office Rainfall data (Oct 21 – Sept 22)



It should be noted that we have only looked at rainfall in the 2 days before a sewage discharge notification. Each catchment is unique and therefore the lag time between a rainfall event and its impact on a sewage overflow could be longer. However, we consider [2] days to be a conservative time period. The SSRS also only provides sewage discharge notifications for designated bathing waters and popular swim spots rather than individual sewage overflows. So where one sewage overflow impacts multiple locations we will be overestimating the number of ‘dry spills’. On the other hand, where multiple sewage overflows impact one location, we will be underestimating the number of ‘dry spills’. Finally, we are unable to comprehensively consider more complex situations such as the effect of periods of drought – when there can be a large increase in surface water after a downpour due to the ground being too dry to absorb it.