If you live on the edge of the earth like Alaska and meet all those unlikely (1 in 10,000,000) requirements, your tap water may be alright. If you are the majority of Earth's population, this is not the case. In terms of chameleons, any assertion you make on water based on health guidelines are for humans and will be foolishly misguided. We know for certain that chemicals in water affect smaller animals much quicker and much more detrimentally than in us. There is a reason reptiles and amphibians are used in these studies...
http://www.sciencedirect.com/science/article/pii/S0147651315301093 60% - 100% of freshwater Bass developing eggs in their testicles from endocrine disrupting chemicals in water.
http://aerg.canberra.edu.au/library/sex_reptile/1996_Guillette_etal_EDCs_in_alligators.pdf Alligators with abnormal reproductive organs and testosterone levels.
http://www.pnas.org/content/99/8/5476.long Atrazine (most commonly used pesticide in USA) causing eggs to develop in testicles of male frogs.
http://web.kitsapsun.com/archive/1998/11-28/0018_environment__airborne_chemicals_f.html chemicals coming from Asia into Westcoast watersheds found to bio-accumulate in fish.
http://www.futurity.org/bpa-turtle-reproduction-899802/ Turtle eggs exposed to BPA turn 100% female, overriding natural process of temperature sex determination.
http://www.environmentalhealthnews.org/ehs/news/2013/toxic-turtles Waste accumulation in sea water is also accumulating in sea turtles, depressing immune function. (yes this is sea water, but these chemicals leach into the sea from fresh water where we draw our tap water from).
http://www.serc.si.edu/education/resources/watershed/stories/salamanders.aspx The
Natural History of Amphibians describes environmental contaminants as "closest to being a "single cause" behind widespread amphibian declines."
http://sydney.edu.au/news/84.html?newsstoryid=14491 Shingleback skinks developing anemia due to agricultural spray.
https://greenrage.wordpress.com/2008/04/20/earth-week-environment-posts-1-oil-spills-and-iguanas/ Galapagos iguanas suffered a severe population decline after a low-level oil spill which altered the digestive bacteria in their gut - this led to malabsorption and ultimately starvation.
In summary, most of the inadequate and
blasé advice that you do find on a hobby forum is in regards to human studies and government statistics, and personal opinions. This is exactly why I posted this thread.. I've been researching water quality for 12 years now and I can tell you that it is very difficult to connect the dots, get honest/thorough information, and in some cases there have been government documents deleted/censored such as the case of "Aluminum and Human Health" published by Health Canada in 2004 and deleted/censored from the archives in November of 2015. What we do know is that reptiles are affected by these interactions more than you are.
Having traveled around the world, and seeing places such as Borneo with a high degree of biodiversity devastated by palm plantations, I predict in the not so distant future that many species of reptiles and amphibians will exist only in private collections and collectors such as those present will require a paradigm shift to a higher standard of husbandry in order to preserve those species until they can be reintroduced to secondary growth or controlled ecosystems. Our understanding of water quality will play a crucial role in this process, particularly when endocrine disrupting chemicals are present. As China's demand for oldgrowth wood from Madagascar increases with an increasing middle class who desire and can afford it, chameleons will be one of the first groups, along with golden toads of Panama and Mexican Axolotls, to depend on captive populations.
It is not simply something to brush off as 'it depends where you live.' Of course, to the general hobbyist with one chameleon, maybe they have no reason to care and an 'it depends' attitude will be enough. But for those of us who have kept chameleons for our entire lives and have vested interest in the understanding of perfect husbandry, there is reason to care.
Another reference for the fact that this is a severely underesearched area:
Ecotoxicology of Amphibians and Reptiles, Second Edition. It's over $200, but luckily there is google books where half of it may be viewed for free:
https://books.google.ca/books?id=__7LBQAAQBAJ&pg=PA547&dq=Ecotoxicology+of+Amphibians+and+Reptiles,+Second+Edition&hl=en&sa=X&ved=0ahUKEwim0fe1iabOAhUL7mMKHUz1DscQ6AEIHTAA#v=onepage&q=Ecotoxicology of Amphibians and Reptiles, Second Edition&f=false