Stainless steel is being increasingly used in hot and cold water service systems

Water Pipe Material in Hospitals - NHS Scotland
An interesting extract


"Scottish Health Technical Memorandum 04-01:"
The control of Legionella, hygiene, ‘safe’ hot water, cold water and drinking water systems

11.8 The materials generally used for the conveyance of water in healthcare premises are stainless steel or plastics. Copper is only used in exceptional circumstances such as, an extension to existing premises with short life expectancy, or very small stand alone premises. Where this is specified, only lead-free solders should be used.


11.9 Substances leached from materials of construction of pipes, cisterns or other water fittings in contact with water must not adversely affect the quality of water stored or drawn for domestic or food production purposes (Water Byelaws (Scotland) 2000).


11.10 Direct gas-fired water heaters are particularly prone to corrosion and scale formation, and the inside of these heaters should be provided with suitable linings to limit these effects. Steel pipes and fittings


11.12 The character of water in Scotland is such that steel, whether galvanised or not, should not be used at all for domestic hot and cold water installations. Any existing premises with such pipework shall have this scheduled for early replacement.


Stainless steel
11.13 Stainless steel is being increasingly used in hot and cold water service systems. Reference should be made to SHTN 2: ‘Domestic hot and cold water systems for Scottish health care premises’.


Copper pipes and copper/copper alloy fittings
11.14 As described previously, careful consideration will be required if copper pipework and fittings are to be specified for healthcare premises in Scotland. Where this is considered to be acceptable either due to the size of the project or the anticipated lifespan of the facility, the following will apply.
11.15 Copper in general is resistant to corrosion. Unless resistant to dezincification, brass fittings must not be used where water conveyed is capable of dissolving undue amounts of zinc from the fitting. External protection from corrosion for buried pipework may be obtained by using copper tube with a factory-applied polythene sheath.


http://www.hfs.scot.nhs.uk/publications/1265986939-v24%2520SHTM%252004-01%2520Part%2520A.pdf