Also I believe you watercool with Distilled Water. Leaks are bad yes but Distilled water inst a conductor until it becomes dirty?
Absolutely 100% PURE water with ZERO contaminants and NO gasses is actually an insulator.(good luck on getting it outside of a specially constructed laboratory)
But no... that does not include distilled water... (actually you would be frightened at the amount of shite in "distilled water" non-laboratory grade)
You use distilled water to reduce galvanic corrosion & oxides forming in the tubes, but good luck on it staying 'distilled'.
A minute layer of oxide reduces heat transfer efficiency. (see furry kettle)
You should stick to a similar metal across all blocks in the system or you run a risk of severe corrosion as aluminum and copper react badly
It is called galvanic corrosion and occurs frequently in shitty kits that mix metals (or cheap china made 'copper'), a single dissimilar metal is enough to kick it off...