(b) No change shall be made in any rate or charge, or in any form of contract or agreement or any rule or regulation relating to any rate, charge or service, or in any general privilege or facility, which shall have been filed by such a corporation, in compliance with an order of the commission, except after thirty days' notice to the commission and to each county, city, town and village served by such water-works corporation which had filed with such corporation, within the prior twelve months, a request for such notice and which shall be affected by such change and publication of a notice to the public of such proposed change once in each week for four successive weeks in a newspaper having general circulation in the county or counties containing territory affected by the proposed change, which notice shall plainly state the changes proposed and when the change will go into effect. The commission for good cause shown may, except in the case of major changes, allow changes to take effect prior to the end of such thirty-day period and without publication of notice to the public under such conditions as it may prescribe. The commission may delegate to the secretary of the commission its authority to approve a change to a schedule postponing the effective date of such schedule previously filed with the commission and to allow for good cause shown the postponement to take effect prior to the end of such thirty-day period and without publication of notice to the public.

(c) For the purpose of this subdivision, "major changes" shall mean an increase in the rates and charges which would increase the aggregate revenues of the applicant more than the greater of three hundred thousand dollars or two and one-half percent, but shall not include changes in rates, charges or rentals allowed to go into effect by the commission or made by the utility pursuant to an order of the commission after hearings held upon notice to the public.

(d) No such corporation shall charge, demand, collect or receive a greater or less or different compensation for any service rendered or to be rendered than the rates and charges specified in its schedule filed and in effect; nor shall any such corporation refund or remit in any manner or by any device any portion of the rates or charges so specified, nor extend to any person any form of contract or agreement, or any rule or regulation, or any privilege or facility, except such as are regularly and uniformly extended to all persons under like circumstances.

(e) The commission shall have power to prescribe the form of every such schedule and from time to time prescribe by order such changes in the form thereof as may be deemed wise. The commission shall also have power to establish such rules and regulations to carry into effect this subdivision as it may deem necessary, and to modify or amend such rules or regulations from time to time.

(f) Whenever there shall be filed with the commission by any water-works corporation any schedule stating a new rate or charge, or any change in any form of contract or agreement or any rule or regulation relating to any rate, charge or service, or in any general privilege or facility, the commission may, at any time within sixty days from the date when such schedule would or has become effective, either upon complaint or upon its own initiative, and, if it so orders, without answer or other formal pleading by the interested corporation, but upon reasonable notice, hold a hearing concerning the propriety of a change proposed by the filing. If such change is a major change, the commission shall hold such a hearing. Pending such hearing and decision thereon, the commission, upon filing with such schedule and delivering to the corporation affected thereby a statement in writing of its reasons therefor, may suspend the operation of such schedule, but not for a longer period than one hundred and twenty days beyond the time when it would otherwise go into effect. After a full hearing, whether completed before or after the schedule goes into effect, the commission may make such order in reference thereto as would be proper in a proceeding begun after the rate, charge, form of contract or agreement, rule, regulation, service, general privilege or facility had become effective. If any such hearing cannot be concluded within the period of suspension as above stated, the commission may extend the suspension for a further period not exceeding six months.

(g) The commission may, as authorized by section eighty-nine-j of this article, establish temporary rates or charges for any period of suspension under this section.

(h) At any hearing involving a rate, the burden of proof to show that the change or proposed change if proposed by the corporation, or that the existing rate, if it is proposed to reduce the rate, is just and reasonable shall be upon the corporation; and the commission may give to the hearing and decision of such questions preference over all other questions pending before it.

(i) The schedule, rates, charges, form of contract or agreement, rule, regulation, service, general privilege or facility in force when the new schedule, rate, charge, form of contract, rule, regulation, service, general privilege or facility was filed shall continue in force during the period of the suspension unless the commission shall establish a temporary rate or charge as authorized by section eighty-nine-j of this article. 11. In case any water-works corporation is engaged in carrying on any business other than owning, operating or managing a water system, which other business is not otherwise subject to the jurisdiction of the commission, and is so conducted that its operations are to be substantially kept separate and apart from the owning, operating, managing or controlling of such water system, said corporation in respect of such other business shall not be subject to any of the provisions of this chapter and shall not be required to procure the assent or authorization of the commission to any act in such other business or to make any report in respect thereof. But this subdivision shall not restrict or limit the powers of the commission in respect to the owning, operating, managing or controlling by such corporation of such water system, and said powers shall include also the right to inquire as to, and prescribe the apportionment of, capitalization, earnings, debts and expenses fairly and justly to be awarded to or borne by the ownership, operation, management or control of such water system as distinguished from such other business. In any such case, if the owning, operating, managing or controlling of such water system by any such corporation is wholly subsidiary and incidental to the other business carried on by it and is inconsiderable in amount and not general in its character, the commission may by general rules exempt such corporation from making full reports and from keeping of accounts as to such subsidiary and incidental business. 12. The commission shall have power to require each water-works corporation to establish classifications of service based upon the quantity used, the time when used, the purpose for which used, the duration of use and upon any other reasonable consideration, and to establish in connection therewith just and reasonable graduated rates and charges; and it shall have power, either upon complaint or upon its own motion, to require such changes in such classifications, rates and charges as it shall determine to be just and reasonable. 13. The commission, of its own motion or upon complaint of any person or corporation aggrieved, may investigate and determine whether the property of any corporation or person actually used within the state in the business of the distribution, sale or furnishing of water for domestic, commercial or public uses, exclusive of property used solely for or in connection with the business of bottling, or selling, distributing or furnishing bottled water, is of a value exceeding ten thousand dollars. Where such value is ten thousand dollars or less, the commission may require such persons and corporations to file with the commission simplified annual reports, in a form and containing such matters as the commission shall prescribe, and may prescribe simplified forms of accounts to be kept by them. 14. (a) Notwithstanding any other provision of law to the contrary, whenever real property owned by a water-works corporation is exempted from taxation pursuant to the provisions of section four hundred eighty-five-d of the real property tax law the rate or charge imposed by such corporation within the taxing jurisdiction providing for such exemption shall be set by the commission so as to reflect fully the reduction in cost of service resulting therefrom.

(b) Notwithstanding any other provision of law to the contrary, whenever a water-works corporation is the recipient of operating assistance provided by a city pursuant to the provisions of section twenty-one-e of the general city law, the rate or charge imposed by such corporation within such city shall be set by the commission so as to reflect fully the revenues to such corporation resulting therefrom. 15. The commission shall provide for management and operations audits of water-works corporations having annual gross revenues in excess of ten million dollars. Such audits shall include, but not be limited to, an investigation of the corporation's construction program planning in relation to the needs of its customers for reliable service and an evaluation of the efficiency of the company's operations. The commission shall have discretion to have such audits performed by its staff, or by independent auditors. In every case in which the commission chooses to have the audit provided for in this subdivision performed by independent auditors, it shall have authority to select the auditors and to require the corporation being audited to enter into a contract with the auditors providing for their payment by such corporation. Such contract shall provide further that the auditors shall work for and under the direction of the commission according to such terms as the commission may determine are necessary and reasonable. The commission shall have authority to direct the corporation to implement any recommendations resulting from such audits that it finds to be necessary and reasonable. Upon the application of a water-works corporation for a major change in rates as defined in subdivision ten of this section, the commission shall review the corporation's compliance with the directions and recommendations made previously by the commission, as a result of the most recently completed management and operations audit undertaken pursuant to the provisions of this subdivision. The commission shall incorporate the findings of such review in its opinion or order. 16. Notwithstanding any general or special law, rule or regulation, the commission shall have the power to provide for the refund of any revenues received by any water-works corporation which cause the corporation to have revenues in the aggregate in excess of its authorized rate of return for a period of twelve months. The commission may initiate a proceeding with respect to such a refund after the conclusion of any such twelve month period.