People have been told not to swim at Mundesley beach due to concerns over bathing water quality.
North Norfolk District Council (NNDC) said people should stay out of the water until the situation was cleared up.
NNDC said: "The council has received notification of water overflow from Anglian Water into the sea at Mundesley, affecting bathing water quality.
"NNDC and RNLI lifeguards are advising against any water bathing at this time until further information is received."
It follows a raw sewage spill at the same beach earlier this year.
A section of the beach stretching south-east from the Anglian Water pumping station was closed in March, after untreated water was released onto the beach.
Mundesley was one of three north Norfolk beaches which lost its Blue Flag status this year over concerns about the quality of the water there.
East Runton, Mundesley and Sea Palling were removed from the Blue Flag list following a drop in rating from 'excellent' to 'good' by the Environment Agency.
Anglian Water and NNDC have been contacted for further comment.
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