I have red coolant at the moment but would prefer green coolant (yes, I'm that superficial).
I have enough distilled water for two or three flushes (and if I end up not using it, I'll just drink it

Oh, and it's a BP 1.8L engine, 180,000kms (if it makes a difference).
Any tips/tricks - like how long you leave the flush in the engine for (5 mins? 5 days?), and whether tap water is enough to flush it out?