Flushing, Bayside and the rest of the 5 boroughs all get their tap water from upstate and it's some of the best, if not THE best, in the country. However, as someone said, quality can still differ due to plumbing in certain neighborhoods or even differences within houses on the same block.
Long Island on the other hand uses mostly aquafier (well) water depending on where you live and is not at the same level as NYC water. There have also been suggestions that the high cancer rates in LI (especially breast cancer, and even in men!) are due to the water. I for one do not drink it unless filtered. I do use it for my tank after RO/DI filter and never had cyano or major algae outbreaks unless I forgot to measure my TDS to check if my filters/resin are too old.
I agree with your thought process though... if your tap is low in phosphates, nitrates and silicates then no reason to us RO/DI since it strips out all the good elements as well. Great stuff
