# The Water Supply (Water Fittings) Regulations 1999, Paragraph 7


(1) No water fitting shall be embedded in any wall or solid floor.
(2) No fitting which is designed to be operated or maintained, whether manually or electronically, or which consists of a joint, shall be a concealed water fitting.
(3) Any concealed water fitting or mechanical backflow prevention device, not being a terminal fitting, shall be made of gunmetal, or another material resistant to dezincification.
(4) Any water fitting laid below ground level shall have a depth of cover sufficient to prevent water freezing in the fitting.
(5) In this paragraph “concealed water fitting" means a water fitting which–
(a) is installed below ground;
(b) passes through or under any wall, footing or foundation;
(c) is enclosed in any chase or duct; or
(d) is in any other position which is inaccessible or renders access difficult.

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Source: https://www.legislation.gov.uk/uksi/1999/1148/schedule/2/paragraph/7 (the official version)
Page: https://openlegislation.uk/water-supply-water-fittings-regulations-1999/schedule-2/paragraph-7
Contains public sector information licensed under the Open Government Licence v3.0. Source: legislation.gov.uk, The National Archives.