【正文】 luid from an appliance when it has reached a specified level point of use point where water is drawn by the user either directly or by connecting an apparatus pollution of potable water any degradation of the quality of potable water protection point location in a hydraulic circuit where a protection unit is installed protection unit device, or device in bination with other hydraulic ponents, which constitutes the protection against backflow type of protection identified operating principle applied to a protection device belonging to a given family upstream side from which fluid flows under normal conditions 4 Pollution of potable water: general observations Water installations, described in prEN 806, due to their design or construction, shall not be liable to generate pollution of public or private potable water supply system by residual matters, harmful water or any undesirable substance. Backflow of used water The quality of the water distributed can be impaired when used water flows back into the potable water system. Connection When there is a mixing of public potable water and any other water supply, the public water supply shall be protected by an unrestricted air gap. The nonpotable or suspicious water distribution work shall be separated and the whole installation marked (for example different coloured pipes). The nonpotable or suspicious water taps shall have markings with clearly visible warning signs. Page 7 EN 1717:2020 169。 ? special uses relating to similar consumers where products are used with low concentrations and presenting no danger for human health (for example authorized water conditioning, air conditioning)。 BSI 012020 Licensed Copy: Institute Of Technology Tallaght, Institute of Technology, Tue May 08 10:39:47 GMT+00:00 2007, Uncontrolled Copy, (c) BSI 1 Scope This standard deals with the means to be used to prevent the pollution of potable water inside premises and the general requirements of protection devices to avoid pollution by backflow. The hygiene protection specifications of this standard are applicable to all the standards for systems or appliances connected to the private supply system for water intended for human consumption. This standard specifies the minimum requirements for product standards of protection units. The product standards are used to detail product specifications. In the absence of a product standard, this standard is used as a reference in order to draw up a specification for the products out of new development. 2 Normative references This European Standard incorporates, by dated or undated reference, provisions from other publications. These normative references are cited at the appropriate places in the text and the publications are listed hereafter. For dated references, subsequent amendments to or revisions of any of these publications apply to this European standard only when incorporated in it by amendment or revision. For undated references the latest edition of the publication referred to applies (including amendments). prEN 806, Specification for installations inside buildings conveying water for human consumption. 3 Terms and definitions For the purposes of this standard, the following terms and definitions apply. air break to drain unobstructed distance between the low point of overflow, discharge or drain of a device or installation, leading from a water apparatus, and the top point of the device which collects this water air gap physical break between the lowest level of the water inlet and the maximum fault level or critical level of an appliance or installation, a feed pipe, or an air inlet orifice incorporated into a hydraulic circuit air inlet orifice designed to admit air from the atmosphere into a hydraulic circuit appliance, equipment device in which the potable water is used and/or is modified . water heater, chemical dosing unit, coffee machine, WCpan backflow movement of the fluid from downstream to upstream within an installation backflow protection device device which is intended to prevent contamination of potable water by backflow contamination result of rendering impure by contact or mixture, to corrupt, defile, pollute, sully, taint or infect Page 5 EN 1717:2020 169。 BSI 012020 Licensed Copy: Institute Of Technology Tallaght, Institute of Technology, Tue May 08 10:39:47 GMT+00:00 2007, Uncontrolled Copy, (c) BSI Foreword This European Standard has been prepared by Technical Committee CEN/TC 164, Water supply, the Secretariat of which is held by AFNOR. This European Standard shall be given the status of a national standard, either by publication of an identical text or by endorsement, at the latest by month of May 2020, and conflicting national standards shall be withdrawn at the latest by May 2020. According to the CEN/CENELEC Internal Regulations, the national standards anizations of the following countries are bound to implement this European Standard: Austria, Belgium, Czech Republic, Denmark, Finland, France, Germany, Greece, Iceland, Ireland, Italy, Luxembourg, Netherlands, Norway, Portugal, Spain, Sweden, Switzerland and the United Kingdom. Annex A of this European Standard is normative, the Annexes B and C are informative. Introduction In respect of potential adverse effects on the quality of water intended for human consumption, caused by the products covered by this standard: 1) this standard provides no information as to whether the products