The quest chain The Lost Seekers is reached here, and all four chapters of that chain are within the Waterworks zone.
The first two chapters are accessed via the entrance near Guard Tember in the northwest corner of the zone. The second two chapters are accessed via a different entrance at the end of the northeast tunnel.
Beside the named items below, the final reward list may also include weapons made of unusual metals, mithral shields, some great low-level clickies, and Bound to Account random equipment with lower minimum level than usual (e.g. no-minimum-level Feather Falling Boots, which is usually ML 5).
These are the named reward items from the quest chain The Lost Seekers:
Lesser Human BaneLesser Human Bane: A bane weapon excels at attacking one type or subtype of creature. Against Humans, this weapon's effective enhancement bonus is +1 better than its normal enhancement bonus. It deals an extra 1 to 6 points of damage against the foe.
Axeblock IIAxeblock II: Passive: Reduces physical damage taken by 4, except from Bludgeoning or Piercing weapons. (Damage Reduction: 4/Pierce, Bludgeon)
Armor Bonus +3Armor Bonus +3: This item surrounds the wearer with an invisible but tangible field of force, granting +3 armor bonus to AC, just as though he were wearing armor.
Armor Bonus +4Armor Bonus +4: This item surrounds the wearer with an invisible but tangible field of force, granting +4 armor bonus to AC, just as though he were wearing armor.