What are three cations and three anions that are commonly found in ground water. Suggest a source for each

Capuchin

Here's a good website:
How Minerals Affect the Water Supplies

It states lots of impurites and where they might come from. You'll have to do a little work (oh dear) to work out the anions and cations. But I don't believe it's anything very difficult, certainly wouldnt take me 2 seconds.