Regulation 9 Reference meters for water
A reference meter for water shall have been tested over the range of flowrates for which it is intended to be used within 12 months before use, and the results of the test shall be such that—
(a)
the range of five consecutive tests at the same flowrate does not exceed 0.5 per cent of the quantity delivered on each test;
(b)
notwithstanding the application of corrections when a reference meter for water is used to test metered supplies the relative error, determined from the mean of five consecutive tests at any flowrate within the flowrate range, shall not exceed 2 per cent of the quantity delivered on any test.