Hard water leaves traces of minerals all over everything, especially faucets and kettles.
The minerals are basically harmless, and easily break down if you keep cleaning it up constantly and focus on making sure it doesn’t go too long without addressing the issue. It’s sort of a pain.
But if you let it build up, it can form rock-hard deposits that can damage your plumbing.
Addressing a breach of trust head-on, right away, can seem really uncomfortable. But it’s always going to be much better than ignoring the problem.