DIN 1988-4 E : 1988

1 Scope and field of application<br>2 General<br>3 Causes of water contamination<br>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;3.1 Backflow<br>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;3.2 Cross-connection<br>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;3.3 Other influencing factors<br>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;3.4 Materials<br>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;3.5 Stagnation<br>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;3.6 Damage to the system due to lack, or lack of <br>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;proper, maintenance<br>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;3.7 Improper operation<br>4 Backflow prevention<br>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;4.1 Single-unit and multiple-unit backflow <br>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;prevention devices<br>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;4.2 Types of safety devices to be used<br>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;4.3 Typical applications of safety devices<br>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;4.4 Backflow protection of water heaters<br>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;4.5 Criteria for the selection of safety devices<br>5 Protection of drinking water in water heaters<br>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;5.1 Types of water heaters<br>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;5.2 Use of chlorinated fluorocarbons as heating <br>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;medium

This standard, in conjunction with DIN 1998 Parts 1 to 3 and Parts 5 to 8, applies to the design, installation, modification, maintenance and operation of drinking water supply systems ('systems', for short) inside buildings and their curtilages. It deals with the possible causes of drinking water contamination and describes measures to preserve the water quality in these systems.