The water company was responding to comments from Network Rail, which blamed Thames Water for the disruption and said it should reimburse passengers.
A burst water mains and a number of other leaks from Thames Water’s network saw water enter Farringdon station at the end of last week, resulting in a section of the rail network being closed on Wednesday night and disrupting trains since the weekend.
After fixing the leak from their network, Thames Water engineers inspected the tunnel and found the drainage system was blocked, meaning the water built up and flooded tracks near the station.
Thames Water director Bob Collington said: “The pipe was full of silt and debris, and a grill which would have allowed the water to drain away was blocked solid. Basically, the water had nowhere to go.”
He added that the issue of the blocked drainage grill was “identified as far back as 2007” and that the problems of the water on the track “have been caused by a lack of maintenance on their part”.
A meeting between Thames Water and Network Rail is scheduled to take place on Tuesday (3 February).
Collington added: “Our teams have done a fantastic job resolving this issue, and we will be presenting our findings to Network Rail as part of a full investigation into what has caused this terrible disruption to passengers.”
The flooding at Farringdon station saw the link between St Pancras and Farringdon station closed, and it has caused a total of 133 hours of delays to commuters.
On Wednesday, Network Rail said Thames Water faces a “multi-million pound bill” for the burst 16 inch water mains and leaks that have caused the disruption to rail travellers.
Network Rail’s route managing director Phil Verster said: “Passengers have suffered a lot this week as a result of Thames Water’s burst and leaking pipes.”
He added: “We expect Thames Water to reimburse passengers, train operators and Network Rail for the significant consequences of these water leaks.”