5. For regulation 4(7) there shall be substituted the following—
“(7) In these Regulations—
“background concentration” means any concentration of the relevant substance which would be present in the release irrespective of any effect the process may have had on the composition of the release and, without prejudice to the generality of the foregoing, includes such concentration of the substance as is referred to in paragraph (8) below; and
“background quantity” means such quantity of the relevant substance as is referred to in paragraph (8) below.
(8) The concentration or, as the case may be, quantity mentioned in paragraph (7) above is such concentration or quantity as is present in—
(a)water supplied to the premises where the process is carried on;
(b)water abstracted for use in the process; and
(c)precipitation onto the premises on which the process is carried on.”.