Toilet problem

[pgl]

Hi
Just wondering if anyone might have any ideas on this. In the last week or so, the downstairs toilet appears to be blocked on and off, i.e, you would flush the toilet, with nothing in it, and it would fill up maybe 3/4 of the way, a few hrs later it might be completely empty, then in the last few days, if you turn on the sink taps in the same room, bubbles come up through the toilet bowl, followed by water leaking onto the ground from the tap pipes, opposite side of the room? The house is only 1 1/2 yrs old. If the problem is further down the line, would this still be the responsibility of the builders?
Any help appreciated.
P

 

[Cashstrapped]

Have the same problem with my own house every so many months downstairs toilet would block/ overflow, tried the brushes (a few times). Finally called the builders, they got 'drain doctor' to clear it and fingers crossed it hasn't re-occured since. They said the cause was some pebble dash and small cement lumps that hadn't been flushed out of the drains from the time the house was built. Didn't have a leak anywhere though so would def. follow that up with the builders.

 

[extopia]

Sounds like your sewer system is not properly vented. Is there a soil vent pipe (a tall 100mm pipe going to above the roof level) anywhere on your system?