Dozens of residents turned up at a public meeting to have their say on the sewage spill which hit Whitby last month.
The firm said a catastrophic failure of one of the sewage pumps caused the problem.

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Untreated waste water was then discharged into the harbour for 52 hours.
But despite including a picture of the broken pump in their presentation, which was available for people to take away from the meeting, Yorkshire Water refused to send a copy to the Whitby Gazette.
A spokesman for the company said they were not allowed to circulate these images to the media for fear of terrorist attacks.
At the meeting, the company said 50 engineers worked flat out to reinstate the pumping station as quickly as possible.
Angry residents also raised concerns at the meeting about Mulgrave Road, which was hit by a sewage discharge probelm at around the same time.
YW say the problem there, which has happened before, is not linked to the Endeavour Wharf incident.
And it has warned that because it is external flooding rather than waste water discharging into homes, it was unable to fund investment there at the moment.

To read more about Yorkshire Water's planned response, click here

To read more about the residents' grilling of water bosses, click here