Leana Hosea and Rachel Salvidge are journalists.
Scientists are concerned that the allowable levels of toxic PFAS are too high in the UK.
Almost half of the samples taken were found to exceed European safety levels. The current UK safety level was not exceeded.
Many products have chemicals in them, such as non-stick pans, food packaging, carpets, furniture, and firefighting foam.
They have been linked to a number of diseases.
According to the UK Drinking Water Inspectorate, drinking water must contain no more than 100 ng/l of PFAS chemicals. Action must be taken to reduce levels.
45 tap water samples were taken by the BBC. None exceeded the 100ng/l level.
Under the current guidelines, local healthcare professionals must be consulted, and levels monitored, if four samples have levels that exceed 10ng/l.
The European Food Standards Agency tolerable limit is 2.2ng/l.
The significance of your results, even though they are small, is that they show that this stuff is in drinking water.
The UK Drinking Water Inspectorate has a level of 100ng/l before action is taken.
Rita Lock-Caruso, Professor of Toxicology at the University of Michigan, said the results raised a potential health concern because they found health effects at lower and lower concentrations.
The most common PFAS chemicals, PFOA and PFOS, have been found to be linked to a number of diseases.
There is concern about the effect on children. A woman may build this up in her body and when she gets pregnant, she shares that with her unborn child. She takes part of her body burden into her milk. The next generation will get a huge dose, and the baby may end up having more PFAS in her blood than her mother has.
The US may reduce its regulatory level.
The former head of the National Institute of Environmental Sciences said that they want them to be as low as possible because water is not the only source of exposure.
There is no public data about its impact in the UK.
Some residents on the Channel Island of Jersey believe they are suffering adverse health impacts from their drinking water.
In the 1990s the government of Jersey discovered that the people of St Ouen had been drinking polluted water.
The government of Jersey has recently agreed to offer free blood tests for people with health issues in the area.
Sarah Simon, a lifelong Jersey resident turned citizen scientist, says that she has an autoimmune disease, her father has a kidneys disease, and her mother has a thyroid disease.
When I talked to our neighbours, I found that many of them had health problems. This cannot be a coincidence.
PFOS and PFOA are not manufactured in the UK anymore. There are still other PFASs that are not regulated.
There are 18 different types of PFAS chemicals in the tap water.
The Department for Environment, Farming and Rural Affairs said in a statement that they have robust systems in place to identify the impact of a range of chemicals on the environment and human health.