How safe is YOUR tap water? We reveal all the scary pathogens that could be in your inventory

Hundreds of people in Devon have been urged not to ‘drink tap water’ without boiling it after a microscopic parasite infiltrated their water supply.

South West Water revealed ‘tiny traces’ of cryptosporidium, commonly known as ‘crypto’, were found in the water in Brixham.

The chlorine-resistant parasite, which can cause vomiting, stomach pain and fever, can survive in water for up to a week.

It is spread through infected feces that enter the mouth.

How safe is your tap water? And what else is in your offer? Can it do any damage?

Our interactive chart below shows the top pathogens we unknowingly drink every day.

The specific level of substances detected varied from country to country and represents only minute traces per liter. Of the thousands of tests performed, only a small proportion yielded a positive result above the threshold values.

Figures from the government’s Drinking Water Inspectorate (DWI) show that bacteria that normally occur in our intestines can sometimes be found in tap water.

Both types, as measured by regulators (E.coli and Enterococcus), can theoretically make people sick, although this is usually mild for most people.

Instead, their presence is normally measured as an indicator that water supplies may have been contaminated by human feces.

Therefore, the DWI sets the limit at 0 bacteria per 100 ml, which means that such bacteria, at least in principle, should never be found in household items.

However, this is not the case: 27 breaches were discovered in 2022. ​​The vast majority (12) came from Severn Trent Water, which supplies water to 4.5 million homes and businesses in the Midlands.

And in 2022, at least 5,577 Britons with private facilities drank water contaminated with feces.

Professor Paul Hunter, a renowned infectious disease expert from the University of East Anglia who has advised the WHO on drinking water standards, said these pathogens are unlikely to make a Briton ill but are good indicators of infection .

“They are generally not dangerous in themselves, but are an indication that the water could be contaminated by feces,” he said.

‘There are some types of E. coli that can potentially cause severe diarrhea, but the most common form of this often does not turn out to be positive even when present.

‘The presence of an indicator E. coli or Enterococcus does not mean that disease-causing bacteria are present, only that we cannot say that they are absent.

‘You could probably drink water that contains quite a few indicator bacteria without getting sick. But the indicators are there, you can’t rule it out.’

He added that another aspect that can cloud the data is that people often contaminate their own tap water by accidentally touching a tap opening while washing their hands after going to the toilet.

This places the bacteria exactly at the opening of the tap and is therefore not an indication that the supply itself is contaminated.

Professor Hunter added that overall, British drinking water is very safe and that only 27 of the more than 150,000 tests carried out were positive, in fact a ‘good’ result.

However, yesterday, UK Health Security Agency (UKHSA) officials said 22 cases of cryptosporidium infection have been confirmed in Brixham.

For most people, cryptosporidiosis – the technical name for the infection – is mild.

It usually goes away on its own, without any treatment, within a few days or weeks.

However, it can be more serious for vulnerable people, such as those with weakened immune systems and the elderly or patients undergoing cancer treatment.

Due to its highly contagious nature, people with symptoms such as diarrhea and vomiting are told not to stay at work or school until they have been free of these symptoms for at least 48 hours.

DWI figures also suggest that pesticides, chemicals made to kill unwanted weeds and pests, can enter Britain’s water supplies through runoff from gardens and farms and from other sources.

The DWI sets a limit of 0.5 μg/l for the total amount of all pesticides in tap water, but for some specific species it is set at 0.1 μg/l.

The latter limit was exceeded three times in 2022, all by water supplied by Northumbrian, Essex and Suffolk Water Ltd.

Other chemicals include PFAS, also called “forever chemicals” because of their ability to persist in the environment for years, copper, iron and even nickel.