On Fri, 8 Feb 2019 13:00:55 +0000, (Roger Hayter)
wrote:

Just a note for the procurement department. I have a 'Zilmet' Italian
made *potable water* 25 litre expansion tank that has been in use for
four years, and is full of rust, including fair-sized rust flakes. Our
water is from the mains and somewhat soft but nothing out of the
ordinary.

So I know what not to buy. Anyone any recommendations?

Check the pH of the water. Is the tank being fed from a local
authourity supply or are you pumping from a well?

If you want to keep using the tank bung some phosphoric acid into it.
Your local waterworks should be doing it anyway if they are feeding
any older properties.

AB