In the spring and fall if the water treatment plants change their source water, which they often do, that could change water quality. And in the spring and fall, if wherever the water comes from also changes because the water in the lakes turn over. That would be my and DH's thoughts. He is a water engineer, and I grew up on the water and saw the changes seasonally. High tannins (tea colored) in the water mixed with chlorine (for disinfection) can created harmful byproducts (cancer causing). These byproducts also have to be monitored. All of this could be less of an issue depending upon what your municipality uses for disinfection of the water (chlorine gas, hypo-chlorite, ozone, etc) Also what type of pipes are in the hotel. Old rusted galvinized pipes. I am sure you know that , Well that is all I have for you.