Not many growers i know take it that far but they should. Especially if its a small town municipal source and your the only grower around. With a true water quality test report you can really tailor a nutrient formula for exactly the solution you need to mix up. Here in my area its a consistent 0.2 EC or 110 ppm on the Hannah 500 conversion scale and 7.4 - 7.7 pH. That 110 ppm is largely cal amd mag carbonates with a smidge of iron. Probably chloromines and fluorides as well but i do not know if these and other chemicals/minerals are measured or register with a simple EC/TDS meter. I used to live in Flint (Clio now...different water thank God) and I remember when NO ONE knew or said anything about the water quality when the City first switched from the Detroit pipeline (for 60+ years) and got the bright idea to pull it from the Flint River to save some cash....people were just beginning to bitch in the news and Flint Journal about the brownish water and swampy taste. My grow operation was in town on this water at the time and I remember making up my tanks as usual one day and my
Bluelab meter went from the ususal 110 ppm to a whopping 300+ ppm. I was like wtf? Thought my trusty meter was acting wonky and then it dawned on me about the news headlines saying they changed to Flint River water. I moved to a small town (Clio) just outside Flint and away from its nasty water idea shortly afterwards. But yes....water quality report is a very smart move for any indoor grower wanting to start out in the right direction as to watering and feeding thier crops.