In respect of any financial year, the sum of the requisition made on any contributing authority and the estimated income mentioned in subsection (1)(b) above shall bear the same relationship to the expenditure incurred by the requisitioning authority in the exercise of all its water supply functions as the estimated volume of water to be supplied to that contributing authority bears to the total volume of water to be supplied by the requisitioning authority, whether for consumption inside its own area or elsewhere.

For the purposes of this section “requisitioning authority” means a water authority such as is mentioned in section 60(1) above.

Where, in the case of any water authority, the Secretary of State considers, having regard to all the circumstances, that it would be unreasonable or inequitable that the methods of calculating the sums to be requisitioned, as required by F1subsections (1) and (2), should apply, he may by order modify the requirements of either or both of the said subsections or specify a different method of calculation and, in either event, may so specify the financial years during which the provisions of the said order are to operate, and in relation to that authority in respect of those years the provisions of those subsections as so modified, or, where the said order specifies a different method of calculation, the provisions of that order, shall have effect for the purposes of this section.

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