The price to be charged by the Council of the City of Wellington for the supply of water to the General Government of New Zealand from the waterworks of the Council, for whatever purpose used, other than for motive-power, the rate for which shall be the same as charged to ordinary consumers, shall, for the term of ten years, computed from the coming into force of this Act, be the uniform sum of six and two-third cents per one thousand gallons. The said General Government shall, during the said period of ten years, obtain from the said Council all water required by it for whatever purpose and which can be supplied from the said Council's waterworks; and the said Council shall not during that period refuse to supply the said General Government with water from such waterworks.