# The Water Supply (Water Fittings) Regulations 1999, Paragraph 21


Every expansion cistern or expansion vessel, and every cold water combined feed and expansion cistern connected to a primary circuit, shall be such as to accommodate any expansion water from that circuit during normal operation.

---
Source: https://www.legislation.gov.uk/uksi/1999/1148/schedule/2/paragraph/21 (the official version)
Page: https://openlegislation.uk/water-supply-water-fittings-regulations-1999/schedule-2/paragraph-21
Contains public sector information licensed under the Open Government Licence v3.0. Source: legislation.gov.uk, The National Archives.