I had our home built 5 years ago. Recently, the joint in the drain line detached and water poored from the walls into out basement. What is the expected life of these joint. I thought the plastic piping was so post last at lease 10 - 15 years if silicone or plumber putty was used to seal the joint. Is this true?

By plastic piping I assume you mean PVC. PVC will be here when they dig up our bones in the future centuries. PVC is joined together using glue which is really not a glue but a solvent. The glue or solvent softens the surfaces of the PVC and the two pieces fuse together. Sort of like welding.

So why did the joint come apart? Improperly made joint. Most likely someone forgot to glue it. Assuming that the two pieces will go back together, get some PVC glue and primer if the pipe is white. Get some ABS glue if the pipe is black. Apply some primer to the pipe and the fitting. Then apply some glue to the pipe and the fitting, shove together and hold for 10 seconds.