A World War II grenade sucked up by contractors cleaning out a Mosgiel sewage drain on Tuesday morning was missing its detonator, say police.
The Mills-type grenade contained explosives but did not have the arm and pin which would have set it off.
"The chances of it exploding were pretty slim," said Senior Sergeant Bruce Ross of Dunedin police.
A section of Mosgiel, west of Dunedin, was cordoned off about 10.30am when contractors sucked up something which blocked their vacuum tube.
"We were sucking out the sewerage and the hose blocked up, which happens all the time," Delta drainage technician Marc Layne told the Southland Times.
"So we gave it a bang on the ground and a bloody hand grenade rolled out."
Layne estimated the grenade weighed around half a pound (0.22kg), and described it as having a "blacky corroded look, like it'd been there for a while," with visible fragment lines, "kind of like a pineapple".
Ross said an army bomb disposal unit from Christchurch, called down to dispose of the bomb, determined it wasn't live about 4pm.
Police did not know how the grenade got into the drain or how long it had been there, he said.
No properties were evacuated but nearby residents had been warned to stay at the rear of their properties.
