I've cobbled this example together using an old paint pot and a drinking straw. If I was going to build a permanent one I'd try and find a slightly smaller pot to go on the top.
Useful for scenarios...
Destroy the water tower! Deprive your enemies of water by destroying the tower - fight your way to it and attach explosive charges to the tower legs - or perhaps you can destroy it from a distance using missiles?
Poison the water tower! Fight your way to the tower and climb it to pour poison/mutagens into the supply.
Steal the water! Your troops are running low on water and a raid on this water tower might save their lives. Spend a number of turns in contact with the base of the tower while you fill water containers, earn more water counters (victory points) for every turn, but make sure you escape before enemy reinforcements arrive. Make some water markers before the game - paint some spare jerry cans or something similar. If you have appropriate models, the mission could be to use escort vehicles to protect a water tanker.
