Two 121.5 megahertz locators were discarded, one in Queenstown and one in Wellington, without being disabled and sparked extensive rescue operations, including helicopter searches, costing the taxpayer more than $5000 each, Rescue Co-ordination Centre New Zealand (RCCNZ) search and rescue officer John Ashby said.
The first beacon was found under rubbish at the Wainuiomata landfill and the second traced to the Queenstown landfill at Gibbston and disabled.
Rescue helicopters were dispatched to both incidents.
From February 1, emergency beacons on the 121.5MHz and 243MHz channels were no longer able to be detected by satellite.
However, signals could still be picked up by aircraft which use the frequency for emergency communications.
Rescue agencies still had a responsibility to follow each reported distress signal, Mr Ashby said.
With an estimated 15,000 to 20,000 of the 121.5MHz beacons still in circulation, the RCCNZ is urging owners to deactivate beacons before disposing of them, or to take them to a local police station or a beacon retailer.
"If the beacon is not properly disposed of, this can lead to a costly and time-consuming search, tying up resources that may be needed to respond to a genuine emergency."
The identities of the discarded beacons' owners were not known, so the cost of the search would be at taxpayer expense, Mr Ashby said.
All old beacons should be replaced with the 406MHz system.
To date, more than 14,000 have been registered in New Zealand.
A Queenstown police spokesman said rather than discarding the old beacons at the dump, people could bring them in to their local police station.
Navcom Electronics director Alan Wilden, of Dunedin, said lithium batteries in the beacons could last for 10 years and should be removed.
Beacons discarded with the batteries in place could trigger a signal if crushed by heavy machinery.
Mr Wilden places the beacons in a vice to remove the batteries before disposing of the unit.
"I am more than happy to destroy each unit if people bring them in," he said.
