Rio 2016: Green Olympic pool drained as organisers reveal hydrogen peroxide caused colour change

80 litres of hydrogen peroxide was dumped into the two pools in the Aquatics Centre without organisers' knowledge

The water polo pool at the Rio de Janeiro aquatics centre will be drained completely after it was revealed that an unauthorised dump of 80 litres of hydrogen peroxide was responsible for turning the two pools a murky green colour in what has been described by organisers as “embarrassing”.

The diving pool inside the Maria Lenk Aquatics Centre looked normal as Tom Daley and Dan Goodfellow secured bronze in the men’s 10m synchronised final on Monday, but come Tuesday the water had changed colour to a dark green.

Organisers confirmed that the water was still safe to enter, although a number of water polo players – competing in the pool alongside the diving one – reported to be suffering from itchy eyes. Various theories claimed that the colour change could be due to the green advertising board, inadequate levels of chlorine and possibly an illegal contamination, but it has been confirmed that the addition of hydrogen peroxide neutralised the chlorine in the pools and meant that algae was able to bloom.

"This is a way of cleaning swimming pools but you're not supposed to combine it with chlorine," Gustavo Nascimento, Rio 2016's director of venue management, told reporters in Brazil. "We were not consulted, our contractor's failure is our failure."

A spokesman for Rio 2016 labelled lamented the ordeal, although they refused to confirm who the independent contractor was that was responsible for the dump of hydrogen peroxide.

"Of course it's an embarrassment," said Mario Andrada. "This was probably the only issue that we were unable to solve quickly."

Organisers have decided to drain the water polo pool only, due to the fact that the synchronised swimming event is due to begin today and that a full 10 hours is needed to drain and refill the pool. The diving pool, which did not cause as many problems for divers this week, will remain as it is with organisers continuing to treat the water in the hope for it to return to normal later in the week.

Nascimento added that the participation of over 120 athletes in the diving pool had added to the “organics” in the water that were responsible for the colour change.