So I live in NYC, and paid for the best aquarium shop in the entire city to build and setup a custom tank for housing an octopus. I had done some reading saying that tap water was not OK to use, but he filled up my tank with tap water. The right amounts of salt, minerals and buffer and whatever else is necessary, but still...it was tap water. As the water evaporates and I refill it...with tap water....I am wondering how concerned I should be about this. Just how bad is city tap water on average? Will the ceph be fine, die straight away or something in between?