https://wiki.project1999.com/Quench_Lasen%27s_Thirst
IIRC (and I've only used this once, so could be off by a bit), this was about 5% of a level at level 3, or 1000 XP per water, 100,000 XP per plat. You need a ton of clicking to do it though, and will go KOS with the Corrupt Qeynos guards.
Theoretically, 600,000 waters would then be 600 million XP for 6000 plat, or about the amount needed to hit 60. You would just need like 800 hours of clicking to get there....