Unlife is strange

In chapter 4, you'll go to the West End district. In a building opposite Kimura Tadao's house you'll find the pure water. The building is kindof between West end and Whitechapel on the map, just under where the line curves back up to vertical. Once you've got the water, the plant is in your office at Pembroke Hospital - water it. Then sleep for 3 or 4 nights. It should then have grown leaves - interact with it to get the achievement. It is not yet known whether this achievement is missable - so aim for it when you get to chapter 4.