Tap water in developed countries used to be assumed to be 100% safe to drink, and most water authorities assert that this is still the case. However, there have been an increasing number of studies that throw some doubt into the picture. The problem seems to be that industrialisation (factories and agriculture) generates a range of pollutants that are increasingly finding their way into drinking water.
An example is this 2016 article in the British Medical Journal
“All drinking water should be filtered to remove toxins”
Toxins in tap water include arsenic, aluminium, fluoride, chlorine disinfection by-products.
Arsenic is carcinogenic, Aluminium has been linked to Alzheimer´s disease and several other problems, and Fluoride is a neurotoxin.
Chlorine and chlorine disinfection by-products are also present in tap water, both of which are toxic to mammalian physiology.
However, bottled water is not necessarily better, as much of it is actually bottled tap water. In addition, drinking any water from a plastic bottle is hazardous due to leaching of bisphenol A (BPA) which is a hormone disruptor (estrogen mimic) which has been associated with multiple health problems, including risk of obesity and various cancers
To preserve health and prevent disease, all drinking water should be filtered. The best type of filter is a granular-activated carbon block filter, which removes most harmful chemicals and metals.
A more recent article was in Environmental Health Perspectives (Jan 2020):
“Trihalomethanes in Drinking Water and Bladder Cancer Burden in the European Union”
A study across Europe showed that bladder cancer was linked to the presence of chemicals called Trihalomethanes (THMs), created as a by-product of chlorination. Of 14 thousand cases of bladder cancer in the UK, more than a thousand were attributable to these chemicals.
It concludes that “Our results suggest that current THM exposures in the European Union may lead to a considerable number of bladder cancer cases that could be avoided by optimizing water treatment, disinfection, and distribution.”
The US Environmental Protection Agency (EPA) sets these safe limits:
These are some of the limits for pollutants in tap water, and the potential health effects of long-term exposure for adults to high levels. (all units are in micrograms per litre: μg/L)
• Trihalomethanes 80 Liver, kidney or central nervous system problems; increased risk of cancer
• Arsenic 10 Skin damage or problems with circulatory systems, and may have increased risk of getting cancer
• Chromium 100 Allergic dermatitis
• Copper 1300 Liver or kidney damage
• Cyanide 200 Nerve damage or thyroid problems
• Lead 15 Kidney problems; high blood pressure
• Mercury 2 Kidney damage
• Fluoride 4000 Bone disease (pain and tenderness of the bones);
They set many individual limits for pesticides etc., including for example these herbicides:
• 2,4-D 70 Kidney, liver, or adrenal gland problems
• Simazine 4 Problems with blood
But are these limits really safe?
It’s worrying that there’s often a big divergence between what different countries view as a safe maximum.
For example, the US safe limit for Trihalomethanes (by-product of chlorination) is 80 μg/L. Most European countries set a maximum limit of 100, although some are lower, and in particular the Netherlands and Denmark impose a limit of 25.
So, who is right? And what’s to say that further research won’t cause the government agencies to lower these limits in the future?
Perhaps the safest route for us all right now is to take no chances, and to assume that the lowest recommended limits are the ones we should take account of.
In my own area, the water company publishes detailed analyses of tests performed, and I’ve listed some of these results below.
‘Amount’ is the maximum found in samples through 2018 in my area. All units are μg/l
|Amount||UK limit||US limit|
So, should I worry?
Maybe not, as most of the measured amounts are way below recommended limits, whether UK or US. Although Copper and Trihalomethanes are maybe getting a little too close for comfort, not least when you also compare that Trihalomethanes figure of 20.1 with the maximum set by Netherlands and Denmark of 25 …
Anyway, I’ve decided to play safe, and now use a water filter!!
BMJ: All drinking water should be filtered to remove toxins: https://www.bmj.com/content/352/bmj.i1214/rr-2
Environmental Health Perspectives: https://ehp.niehs.nih.gov/doi/10.1289/EHP4495
Link to my post “Water Filter”