The Legionella bacteria that resulted in Seven Kings High School being closed yesterday were found on Monday night, it has emerged.

Pupils and parents were unaware of the problem when the school, in Ley Street, opened as normal yesterday (Tuesday), before students were sent home around 11am.

Mum Nanditi Bhatia said she did not know about Legionella, which can cause the potentially fatal Legionnaire’s disease, until she receieved an email from the school yesterday evening.

She added: “The first letter said there was a problem with boilers and I was wondering why they would send children home just for that.

“My daughter is a special needs child so I was a bit worried about her but she’s fine.”

Sabrina Ben Salmi’s half-brother, Dami, is a pupil at the school.

She said she was “alarmed” at him going back to school so soon after the Legionella was discovered.

Sabrina, of Eton Road, Ilford, said: “Why did they allow the kids to go back to school?

“The should have sent letters out and stopped people going in on Tuesday. It doesn’t make any sense.”

A letter on the school’s website yesterday said a “problem with the water supply” had stopped hot water and toilet facilities working and there was “no alternative” but to send children home.

A Redbridge Council spokesman said Legionella was discovered during “routine tests”.

He added: “Council officers needed to check what parts of the water system within the school were affected before any decision about closing the school was taken.

“The checks were carried out immediately on Monday evening and the affected areas were isolated after school hours.

“The headteacher met with her leadership team and a range of council staff at the earliest opportunity, first thing on Tuesday morning, to establish what facilities were available.

“The outcome of the meeting indicated that the school could not guarantee sufficient hot water as well as toilet and cooking provision for the whole school.”

The school was open as normal today (Wednesday) after the water system was treated and boilers replaced.