I've had problems with our main drain blocking for about 10 years now. Every 9-12 months it blocks and I had to rod it. I had it down to a fine art with a 20 meter length of class 10 HDPE pipe and it usually took me about 15 minutes. I tried clearing it last week and for some reason it just wouldn't clear so I got in a company with one of those water pump and snake machines. 2 hours later they gave up and suggested I start digging. So I did.