Divers were unable to train on Friday morning when the green Olympic diving pool was closed to competitors.
The water at the Maria Lenk Aquatics Centre began to cause concern on Tuesday when it turned from its previous blue to a murky green.
It has remained that way since, with world governing body FINA explaining the water tanks had run out of some of the chemicals used in the water treatment process.
It stressed that there was no health risk to the divers but Britain's Tom Daley tweeted his concern after being unable to train for the individual 10 metre platform event on Friday morning.
Daley, who won a bronze with Dan Goodfellow in the synchro, said: "Diving pool is closed this morning. Hopefully that means we haven't been diving in anything too bad the last couple of days!"
Diving pool is closed this morning. Hopefully that means we haven't been diving in anything too bad the last couple of days! 😷😷😷— Tom Daley (@TomDaley1994) August 12, 2016
As approved by @fina1908, diving training is cancelled b/c the water must be still for the pool to return to its blue color.— Rio 2016 (@Rio2016) August 12, 2016
Games organisers were expected to explain the decision at a briefing later on Friday morning.
The Rio 2016 organisers' official Twitter feed replied to Daley's post. Rio 2016 said: "@TomDaley1994 As approved by @fina89, diving training is cancelled b/c the water must be still for the pool to return to its blue color."
Rio 2016 main spokesman Mario Andrada told Friday's press briefing: "Training was cancelled this morning. We need the water to be still so we can clean it more easily and faster. The water quality does not offer any threat to athletes."