Dear Person

I have recently experienced some issues in our two and a half year old septic tank / leach drain system.
The Water Closet was blocking and a plumber came, inserted a CCTV camera from the outside inspection hole - this revealed root intrusion at the 90 degree elbow to the pan. He cleared the blockage with his cleaning machine and all was OK. As this is a new system we asked the builders plumber why we were getting root intrusion after 2.5 years. He has not responded as yet.
Two weeks ago we then observed a puddle of wastewater on the ground which is situated between the septic tank and the leach drain. This has been getting worse each day and is becoming a health hazard. We have recently experienced heavy rains which is not helping the ground absorbing the wastewater.
The builders plumber has also not responded to this question either. Is this a serious issue, should I continue waiting whilst the wastewater continues to rise or should the matter be investigated immediately. What would be the cause of the leak after all this time of working OK. We live on a treed block in the hills area of perth.

Arthur