Two young boys are now in the care of relatives after they were found by police living at a massive hydroponic cannabis set up in southwest Sydney.

Police raided the drug house in Liverpool at 7am (AEST) on Wednesday, uncovering 186 cannabis plants worth about $810,000 in what they called an "elaborate hydroponics set-up".

Police discovered two boys aged just 10 months and four-years old at the home.

They have since been placed in the care of relatives, while the matter has been referred to the Department of Community Services (DoCS).

During the raid police also arrested two adults at the Liverpool house, a 37-year-old man and 28-year-old woman.

Police could not confirm if they were the boy's parents.

Both have since been charged with a cultivating a commercial quantity of cannabis and with "expose child".

The pair have been refused bail to appear at Liverpool Local Court on Thursday.