A major rescue operation was launched for the 46-year-old stuck up to his waist in sand in the three-metre deep hole.
Emergency services were called to the home on Orbell Road in Hillarys about 3pm (5pm AEST) today.
The man was about three metres down the hole, which he and his landlord had apparently been digging over the past four days in search of a sewer line.
"They just want to find the main sewer, so they can connect the existing pipe to the main sewer, splitting these two houses, that's all it was," the man's housemate said.
The sand gave way this afternoon, trapping one of his legs, and the remaining ground was thought to be unstable.
An exclusion zone was set up around the hole in the backyard as the teams tried to relieve pressure on the hole to stop it from caving in.
As urban search and rescue crews worked to shore up and stabilise the hole, the man remained in good spirits, although somewhat embarrassed, and was given a towel and water.
A specialist vacuum truck was eventually brought in to assist with the rescue and remove the sand and the man about 6.30pm.
The man was taken to hospital in a stable condition for assessment.
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