The legal requirement:
As written in “The Water Resources Act” 1991 Part III, Chapter II
85.- (1) A person contravenes this section if he causes or knowingly permits any poisonous, noxious or polluting matter or any solid waste matter to enter any controlled waters.
(3) A person contravenes this section if he causes or knowingly permits any trade effluent or sewage effluent to be discharged –
(a) Into any controlled water, or
(b) From land in England and Wales, through a pipe, into the sea outside the seaward limits of controlled waters.
(4) A person contravenes this section if he causes or knowingly permits any trade effluent or sewage effluent to be discharged, in contravention of any prohibition imposed by section 86 below from a building or any fixed plant –
(a) Onto or into any land; or
(b) Into any waters of a lake or pond which are not inland fresh waters.
(5) A person contravenes this section if he causes or knowingly permits any matter whatever to enter any inland fresh waters so as to tend (either directly or in combination with other matter which he or another person causes or permits to enter those waters) to impede the proper flow of the waters in a manner leading, or likely to lead, to a substantial aggravation of – (a) pollution due to other causes; or (b) the consequences of such pollution.
(6) Subject to the following provisions of this chapter, a person who contravenes this section or the conditions of any consent given under this chapter for the purposes of this section shall be guilty of an offence and liable – (a) on summary conviction to imprisonment for a term not exceeding three months or to a fine not exceeding £20,000 or to both; (B) on conviction on indictment, to imprisonment for a term not exceeding two years or to a fine, or to both.