They can become breeding grounds for bacteria. When I'm working in the yard, I'm tempted to take a drink from my garden hose. However, there is a type of hose on the market that is made with a food-grade plastic that is approved by the US Food and Drug Administration. This type of hose will not contaminate the water. A chemical called a disinfectant is added to the drinking water at the treatment plant.
Chlorine is the most common disinfectant used in the United States and Canada.
In the United States, chlorine is used in 75 percent of the large water systems and 95 percent of the small ones. Although private well water often may be germ free, and thus usually it not disinfected, it should always be tested to uncover any possible germ contamination. Use cold water. Hot water is more likely to contain rust, copper, and lead from your household plumbing and water heater. There is a blue-green stain where my water drips into my sink.