You can use XLSTAT software to perform a complete statistical analysis of your water sampling. Please follow the link below to a YouTube channel where you can find a detailed tutorial about the application, good luck
In addition to the answers above, this link is to a more generic paper explaining the mathematical basis; i.e. the 'how and why' principal component analysis work
https://www.cs.cmu.edu/~elaw/papers/pca.pdf
and this is a good overview of how to interpret a Dendogram