Potions last a whopping 31 seconds when you use them. The cooldown on potions is 45 seconds. That leaves a long time where things can go bad.
Maxxed alchemy will allow you to spend 3 points into Medicinal Use. This skill increases the duration of your potions from 31 seconds to 42.5 seconds. This allows you to have a potion active almost all of the time!!
Here's what you need:
250 Blessed Thistle
20 Clear Water (level 10 water)
40 Pristine Water (level 20 water)
45 Cleansed Water (level 30 water)
60 Filtered Water (level 40 water)
80 Purified Water (level 50 water)
For much faster results you will need the Multicraft Addon.
How to do this (if your alchemy is level 1):
1. Make 20 potions using the level 10 water
2. Put a skill point into Solvent Proficiency
3. Make 40 potions using the level 20 water
4. Put a skill point into Solvent Proficiency
5. Make 45 potions using the level 30 water
6. Put a skill point into Solvent Proficiency
7. Make 60 potions using the level 40 water
8. Put a skill point into Solvent Proficiency
9. Make 80 potions using the level 50 water
Congratulations on becoming an ALCHEMIST MASTER!!