# Council Directive of 21 May 1991 concerning urban waste water treatment (91/271/EEC), Division 3

Extent: E+W+S+N.I.

The minimum annual number of samples shall be etermined according to the size of the treatment plant and be collected at regular intervals during the year:
— 2 000 to 9 999 p.e.:
12 samples during the first year.
four samples in subsequent years, if it can be shown that the water during the first year complies with the provisions of the Directive; if one sample of the four fails, 12 samples must be taken in the year that follows.
— 10 000 to 49 999 p. e.:
12 samples.
— 50 000 p.e. or over:
24 samples.

---
Source: https://www.legislation.gov.uk/eudr/1991/271/annex/I/division/D/division/3 (the official version)
Page: https://openlegislation.uk/eu-directive-1991-271/annex-I/division-D/division-3
Contains public sector information licensed under the Open Government Licence v3.0. Source: legislation.gov.uk, The National Archives.