I can see the headlines now
"Student and Teacher found fried"
wash your components in the pure water before you submerge it in whatever container will have the rest of the liquid...that should help in getting rid of the impurities.
Hard drive dies in water. Try to use distilled water as it should work.
I don't understand why you said this when he says he's going to get PURE water...meaing distilled, deionized and de-everything like he said...pure H20 no other crap in it.
Chances are it probably won't work really great...I only say that because that water won't stay 'pure' for very long.
You'd still need a heatsink for the CPU though as that water would be around room temperature and the CPU would still die pretty quick.
Good luck on that