Why shouldn't I drink water from the tap?
This or similar is what the water pipes look like in Germany. Even the Umweltbundesamt recommends: water that has stagnated in the pipes for more than four hours should not be used for preparing food and drinks. The biofilm in the pipes is a veritable breeding ground for germs.
Accordingly, Lund University in Sweden has found up to 10 million microbes in every glass of water from the tap. The reason for this is that a biofilm of insects, bacteria and other invertebrates develops inside the water pipes. There are up to 10,000 different microbes in the biofilm! There are no limit values for microbes in biofilm. In a nationwide study by the Institute for Medical Parasitology in Bonn, parasites could be identified in all drinking waters examined. The massive amount of parasites from the "incubator" supply pipe cannot be regulated by the body and infestation occurs.
An amazing fact was made by Georges Lakhovsky in the last century. In his book The Secret of Life, he describes his search for the cause of the spread of cancer. To do this, he and a commission of international cancer specialists visited localities where no cancer patients were registered. They found out that there were no water pipes of any kind in all these villages. The inhabitants drew their water exclusively from wells in the vicinity. When these wells were later replaced by piped water, cancer cases also occurred there.