This wires around the top and sides of the water tower are temporary safety lines often used during construction or maintenance work. Most likely this water tower will have some repairs done to it in the near future.
That is an Outdoor Rated, Continuous Duty, Mobile Cart Air Sampling System
https://viewing.nyc/youve-seen-them-around-the-nyc-subway-so-what-is-this-weird-box-actually-used-for/
This wires around the top and sides of the water tower are temporary safety lines often used during construction or maintenance work. Most likely this water tower will have some repairs done to it in the near future.