A Working Lunch viewer has alerted the BBC to a potentially harmful chemical contamination of Volvic mineral water.
Working Lunch commissioned a laboratory to test the water
The two suspect bottles were brought to our attention by Lauri Pastrone, and we sent one off for testing.
The company says it is taking the matter very seriously.
Volvic produces more than three million bottles a day, fuelled by demand from health and safety conscious consumers.
Volvic even says that you can give it to babies because it has a low mineral content and is "a natural product with no added chemicals".
Lauri Pastrone was therefore shocked to discover that when she opened two bottles they both tasted strongly of chemicals.
She told the programme: "I opened my daily bottle of water and took a large sip from it and immediately noticed that there was a very, very foul taste and smell.
"I ran to the sink, spat it out and as I looked down into the sink I noticed that the water separated into little pools.
"I felt some burning in my throat.
"My husband came and smelled the water and recognised there was something terribly off. He sat me down and encouraged me to drink as much water as I could from the tap.
"He then proceeded to check the remaining bottle that was packaged in that six pack of water and once he smelled that, he realised that too was terribly off."
Following the programme's broadcast, the Food Standards Agency said: "Danone reported this incident to their local authority this morning but did not inform the Agency as they considered this a localised incident not affecting any other water.
"The Agency will however investigate the full circumstances of the incident and issue advice if needed."
In a scientific report commissioned for Working Lunch, a laboratory tested the water.
Its tentative findings showed that the water contained a potentially harmful chemical called naphthalene.
We asked an independent environmental toxicologist, Dr Mark Viant, for his opinion on the findings.
"You would not expect to find Naphthalene in drinking water," he told us.
"It is a naturally occurring chemical that is found in different types of fuel and also in coal tar.
"It is also used in the manufacture of plastics, and is the sweet smelling chemical that you smell in mothballs.
"Now if it was found in drinking water, the critical question would be at what concentration is it found?
Volvic produces three million bottles of water a day
"So at very low levels Naphthalene would not be toxic and it would not be a health risk, but at higher concentrations it can induce or cause damage to the red blood cells in our bodies and this can result ultimately in liver damage."
Volvic is owned by the international food conglomerate Danone.
They told us: "Danone Waters is actively investigating the exact cause of this problem.
"However, the company can confirm that it is an isolated incident and no other complaints have been received from the same batch of product and remaining samples have been checked.
"However, initial research suggests that the naphthalene could have penetrated the plastic after it left the factory at some point in delivery or storage. This has happened in past cases the company has experienced.
"Naphthalene has a very strong smell at very low levels and any problem is immediately obvious on opening the bottle.
"Consumer safety and product quality are very important to Danone and the company is taking this incident very seriously."