If your roses are getting a good 6 hours of sunlight per day, you have fed them well and watered them well, it could indeed be the well water. Test the pH of your soils where the roses are planted. Also have the pH of your well water tested. It could be that the well water is on the alkaline side. Roses do best with a soils pH around 6.5. Having the pH out of wack can tie up the nutrients that are in the soils such that the roses cannot take them up properly. Here are a couple links to articles for you too:
https://www.gardeningknowhow.com/ornamental/flowers/roses/rose-soil-preparation.htm
https://www.gardeningknowhow.com/ornamental/flowers/roses/no-blooms-on-roses.htm