Water
Many visitors to a foreign city want to know if you can drink the water. Well in Vienna, mineral water comes out of the taps. And I’m only half joking.
You never realized how bad the tap water is back home until you experience the Viennese equivalent; over 95% of Vienna’s water comes through two pipelines direct from the alps. They don’t even need to pump it - gravity does the job for them.
These supply areas have no significant industry and few people all told (it’s basically mountains and not a lot else). As a result, the tap water is very high quality, low in nitrogen, has no measurable pesticide residues and, frankly, tastes as good as any mineral water you’re ever likely to drink.
In other words, you need have no worries at all about drinking or using the tap water.
Tip: As you wander the city you’ll sometimes come across water fountains put there for your refreshment. These are labelled “Trinkwasser” (drinking water). If you see a sign “Kein Trinkwasser” that means the water is not suitable for drinking, as is the case with some large fountains, for example.