One of the problems with dogs in New York City is using the word dog in the same sentence as problem. I have done that twice in the first sentence, so I imagine that I am in trouble already with dog owners.
Lest I be characterized as a dog hater, which is in the same realm as child haters, I do like dogs. New York City has 1.4 million dogs, which, I think it's fair to say, poses numerous problems and difficulties, the issues of toiletry being one of the biggest to non-owners.
In 1978, New York City, under Mayor Koch's administration, passed Health Law 1310, the first enforced “poop scoop law” in the country. Prior to that time, the city streets were a virtual minefield of animal waste, and a walk on the sidewalks or in the streets necessitated constant vigilance and agility, or you had to be prepared for the unpleasant task of shoe cleanup.
The city is not particularly hospitable to living creatures, be they plants or animals, dogs included. Days alone at home in small apartments and leash laws do little for their psychological well being. Dogs need off-the-leash time, and now parks have hours and specific locations for this activity. Many parks have also provided dog runs which include toilets.
New York is a city of work-arounds, accommodation, innovation, adaptation and resourcefulness. Dogs need drinking water, and in this summer's heat wave, the need is often dire. Owners prepare and respond to this need in a variety of ways, often carrying water. Others, caught unprepared, often enter retail shops and ask for a cup. Recently, I have noticed the frequency of a preemptive solution - many shop owners providing a bowl on the street with a sign like that in the photo, Water 4 Dogs :)