The green-water incident in the Rio 2016 Olympic pools, had a huge media impact, so much so that whoever reading these lines will already be visualising the image. However, any technician from this sector or any private pool owner knows that it isn’t a strange problem, as a simple chemical analysis of the water allows the origin of the problem to be detected.
edge
The water in a pool can turn green for a few reasons: a lack of free chlorine, an out-of-control pH, the presence of phosphates or nitrates in the water, or an excess of copper or iron. All of these can be detected quite simply, especially in an Olympic pool that has advanced treatment systems. Despite what the Olympic spokesman Mario Andrade said, chemistry is an exact science.

What was really scandalous was the secrecy maintained by the organisers, their refusal to disclose the water analysis and the different contradictory official versions of what took place. In my opinion, this shows that they knew perfectly well that the water had turned green through human error. As admitting this would have been even more ridiculous, they emptied the pools and started again from scratch.

Perhaps we will never know the chemical cause of that shade of emerald, nor is there any need to. Luckily, the Rio competitions continued free of notable incidents and they were deemed as a great success for Brazil. However, as aquatic professionals, it is important to us that this kind of incident doesn’t portray a mistaken image of our sector.