The three family members who tragically died inside a water tank on Thursday night can be named as Andrew, Anne and Richard Basnett.
Husband and wife Andrew and Anne, and Andrew's brother Richard, were described as "pillars of the community" and "good country people" by devastated friends and neighbours.
The three were found dead inside a concrete water tank at their property near Oolong, between Yass and Gunning.
Andrew, 69, collapsed while cleaning the empty cement water tank with a motorised water pump. Wife Anne, 63, and brother Richard, 68, went to his assistance but also collapsed.
They are believed to have been poisoned by carbon monoxide gas that built up in the tank as the water pump was used.
His wife is believed to have called neighbours before entering the tank, who then contacted emergency services.
The bodies of the three were found inside the tank.
Acting Superintendent Andrew Koutsoufis of Hume Local Area Command said the cause of death was being investigated.
"There was a petrol pump being used to clean the tank and that may have been the cause of the build-up of fumes at the bottom of the water tank," he said.
"It appears that it was lowered into the tank and that's caused the gases to be at the bottom of the tank."
He said the teams called to the scene had to wait for gas levels to recede before retrieving the bodies.
Superintendent Koutsoufis said the "close-knit town" was "hurting at the moment" and the family who lost three relatives were devastated.
Neighbours said the couple had farmed the property since the early 1980s at least and their contribution to the town of Gunning would be sorely missed.
They leave behind three adult children, living in Sydney, as well as a number of grandchildren.
Deputy mayor and close family friend Kim Turner paid tribute to the couple.
"It's a massive loss for the community. They were great community people, and the loss is insurmountable, not only in Gunning, but throughout the region.
"I personally will miss both of them enormously."
"We are devastated. It is safe to say we are all in shock. They were lovely people," said one neighbour who did not wish to be named.
Police and other emergency services were called to the rural property, just off the Hume Highway, on February 16 about 6.20pm.
Emergency services personnel retrieved the bodies from the tank near the front of the property just after 9pm.
The deaths are not being treated as suspicious. A brief will be prepared for the information of the coroner, as officers from the Hume Local Area Command have established a crime scene to be examined by forensic officers.