Chichester WwTW

Storm overflow run by Southern Water, discharging into Chichester Harbour.

Storm tank at sewage treatment works - with treatment Shellfish water Chichester constituency
Right now
Not discharging
Last discharge ended on (1 day ago).
Times are UK time. Company feed updated 2 min ago

"Not discharging" means the company's monitor reports no discharge right now — not that the water is clean. The feed publishes status only; no discharge volume is measured.

2026 so far
74spills
at least 2,475 h discharging on 74 days · counted by us, not yet official · 3 discharges whose end the feed did not report (counted, no hours)
2025 official
62spills
985 h · −24% on 2024
Rank in Southern Water
#37
of 970 overflows by 2025 spills (1 = most)
Monitor in 2025
98.3% working
Long-term average 55.7 spills a year

Year by year

The Environment Agency's official annual returns, counted the EA's way (12/24-hour spills). 2026 is our own running count, the same way, from Southern Water's monitor log and the live feed. The feed reports only each overflow's latest discharge, so a discharge it moved past before we saw it end is counted as one spill with no hours: the hours are a floor. The official figure is published next spring.

2024
82 spills · 1,576 hmonitor 99.1%
2025
62 spills · 985 hmonitor 98.3%
2026so far
74 spills · at least 2,475 h

A spill is the EA's 12/24-hour count: the first 12 hours of a discharge count as one, each further 24 hours with discharge as one more. "Monitor" is the share of that year the monitor was working, so a 0 beside a working monitor is a real zero; "no data" means the monitor produced no usable data that year — not zero. Years before 2024 are matched to this site by name and location, because the EA's site IDs changed that year; a monitor figure beside one of them means the outlet's permit confirms the match.

Twin outlet

Southern Water runs another overflow within 300 m that also discharges into Chichester Harbour. They share the sewer and the storm, so one outlet's figures are only part of what reaches the water.

0m Chichester WwTWSWS00173Chichester WTW 2 SSO - 115401 4spills in 2025

This overflow (Chichester WTW 1 SSO - 115402): 62 spills in 2025. Distances are between the published outlet points. The names in brackets are Southern Water's own, from its return.

What the 2025 return says

From Southern Water's annual return to the Environment Agency for this overflow.

High-spill review
Performance - GW inundation
Investigation
Env Act (SODRP) investigation ongoing, UWWTR investigation ongoing
Improvement work
No improvement action in reporting period
Monitored since
2016
Water body
CHICHESTER HARBOUR

This overflow spilled often enough to trigger the EA's high-spill review; the review line is the company's own stated reason.

Discharges we have recorded

72 discharge periods since 2 Jan 2025, 3 whose end the feed never gave. 68 of them come from Southern Water's own event-duration-monitoring records (from its Rivers and Seas Watch service, Jan 2025 – May 2026); the live feed adds anything after that. The official annual count is the figure to quote.

Show 30 earlier (of 72)
StartedEndedDischarge time
52 min
17 min
16 min
21 min
21 min
16 min
13 h 17 min
3 h 15 min
13 h 55 min
1 d 14 h
15 h 5 min
not captured, before not captured
16 h 35 min
14 h 23 min
36 min
15 h 50 min
15 min
1 d 0 h
15 h 45 min
26 min
18 h 2 min
22 h 55 min
90 d 23 h
5 h 24 min
7 h 19 min
13 h 48 min
23 h 31 min
1 h 57 min
4 h 7 min
1 d 9 h

The year figures above use the EA's 12/24-hour counting method, so they are comparable with the official figures; the monitor log's 103 raw blocks were merged into 72 continuous discharge periods (gaps under 15 min joined).

What the feed showed

FloodRadar's own record of every change of state Southern Water's live feed has shown for this overflow, kept since : 4 states. The feed publishes its status now and its latest discharge, nothing older; the discharges above are read from this. It is here so the figures can be checked.

Show the last 4 states
SeenStatusSinceLatest discharge
Not discharging →
Discharging → no end yet
Not discharging →
Not discharging →

Rain nearby last 30 days

Nearest live rain gauge: Rainfall gauge nr Apuldram, 0.4 km away. Brown shading = when this overflow was discharging; ▼ = a discharge start.

Overflow shading is a timing match, not proof of cause — heavy rain and spills share a trigger. Times come from the water company’s event-duration monitor (site status only; no discharge volume is published).

Where it is

Nearest river gauge
Chichester Tozer Way (River Lavant) · 3.2 km
Nearest rain gauge
Council area
Chichester District
Southern Water's own name for it
Chichester WTW 1 SSO - 115402
Site reference
SWS00172 · permit W00137
Coordinates
50.82716, -0.81056

Tell me when this overflow discharges

One message when the company's monitor reports a new discharge here. At most one every 6 hours.

Setting this alert needs JavaScript. The alerts you already have are on your alerts page.

The alert repeats the monitor's status: whether the overflow is discharging, not how much or why. It can only tell you about a discharge that starts after you turn it on.

Concerned about this overflow?

Report pollution you can see or smell to the regulator straight away; the company handles complaints about the overflow itself.

Write to the MP

The Environment Agency's return places this overflow in the Chichester constituency. An MP can ask the company and the regulator questions on a constituent's behalf. These words carry the official figures; change them as you like.

The link opens Parliament's own "Find your MP", which gives the MP's name and how to write to them. FloodRadar sends nothing and keeps nothing you write. Check the constituency against your own address: an MP acts only for people who live in it.

Live status: © Southern Water storm overflow activity data, licensed under CC BY 4.0. Annual spill figures: Environment Agency Event Duration Monitoring return, © Environment Agency copyright and/or database right, Open Government Licence (OGL) v3.0. Spill-event history: Southern Water's Rivers and Seas Watch release history (riversandseaswatch.southernwater.co.uk), © Southern Water. Shown by FloodRadar: only releases Southern Water marks Genuine and that have ended; those it marks Not Genuine or still has under review are left out. Discharges marked "via Top of the Poops", come from Top of the Poops' record of the same company feed, used under CC BY-SA 4.0: the feed's own start and end times as its pages print them, not their derived hours. Times are shown in UK local time. FloodRadar republishes the monitor's status and the EA's figures; it does not measure discharges itself. Constituency and council area from the EA's return: contains OS data © Crown copyright and database right 2026.