Although this is an old post, people are still viewing it and, presumably, looking for an answer. To make Piper diagrams displaying water geochemistry, there is a newer function available called PIED Piper. I've used it and recommend it because there is a lot of functionality. A paper explains much of what you can do with it and gives examples: https://ngwa.onlinelibrary.wiley.com/doi/abs/10.1111/gwat.12953?af=R
It is available at:
