Thanks to all who have responded...(including the moonshine method
)
I have it sorted (almost) now.
I did a Google and have found 2 or 3 companies who will post 5 litres distilled water for a 'reasonablish' cost of £10.
I have further researched the 'water' issue. I have had telephone discussions with the Quality Assurance & Certification Manager of a major company pharmaceutical supply company who supply 'Pure Water B.P.' to chemists (pharmacies). Pure water BP is de-ionised.
He assures me that the 'Pure Water BP' cannot cause corrosion. He has sent me the tech sheets and certification papers and has asked me to forward them on to Zalman - which I will do.
That said and noted, I still feel that I want to use what is recommended by the manufacturer; distilled water and the Zalman ZM-G200 Anti-Corrosion Coolant.
As a point of interest, the ZM-G200 Is the same liquid as the ZM-G300 except the 200 is twice the quantity!