Take on the Justin sidequest of finding the microwave or marks server quest and you should find a pool.
Only do the sidequest you are asked to do don't do two together if you get the opportunity.

you can place blocks in the area of the pond / pool but you have to carry a the full storage container out so best if you have a stair keycard 1 or 2 accessible through piping rooms in order to carry it.

thank you!

or farm alot of potato and plant potato using potato instead of using potato seed so you can turn potato seed into chemical in chemical table.

Originally posted by Brokutt:

or farm alot of potato and plant potato using potato instead of using potato seed so you can turn potato seed into chemical in chemical table.

Agreed -- the chemical pool is just designed to waste your time. Better off planting with your spud gun, and using either/both chemical recipes. You get more chemical in less time for less effort unless your main base happens to be sitting immediately adjacent to the Headquarters.