When police forced open the door of the family’s city centre apartment, they found the father in the process of flushing a quantity of amphetamines down the toilet, TV4 reports.
Police found a quarter of a kilo of amphetamines on the premises but suspect the family of handling and selling up to a kilo of the drugs.
“We’re trying to investigate whether the man managed to flush anything by checking the water seals,” said police spokesman Magnus Andersson.
The man’s wife and their two sons, 32 and 25, are also being held as suspects. Both sons have previous convictions for drug offences.
Police said the family had been under observation for quite some time. A female dealer was previously taken into custody on suspicion of purchasing narcotics during her regular visits to the family.
Police have also arrested around ten more people suspected of buying drugs from the woman.