shall, directly or indirectly, by any special rate, rebate, drawback or other device or method, charge, demand, collect or receive from any person, firm or corporation, a greater or less compensation, for any service rendered or to be rendered, than it charges, demands, collects, or receives from any other person, firm or corporation for doing a like and contemporaneous service under the same or substantially similar circumstances and conditions.
It shall be unlawful for any public utility subject to the provisions of this chapter to make or give any undue or unreasonable preference or advantage to any particular person, company, firm, corporation or locality, or any particular character of traffic or service, in any respect whatsoever, or to subject any particular person, firm, corporation, company or locality, or any particular character of traffic or service, to any undue or unreasonable prejudice or disadvantage in any respect whatsoever.
Nothing in this section shall be construed to prevent the
(a) Authorizing or requiring any rate design consistent with the purposes and policies set forth in article two-a of this chapter; or
(b) Authorizing a private water utility to voluntarily implement a rate design featuring reduced rates and charges for service to qualifying low-income residential customers.