There is no set time period to replace kitchen sink plumbing. A properly installed plumping system that is well-maintained will last a lot longer without needing to be replaced. Generally, there are a few indicators that you need to replace your kitchen sink plumbing. If it is costing you a fortune in repairs, for example, it may work out cheaper in the long run to replace it all with new plumbing. Secondly, if you are getting a new kitchen fitted, then you might as well replace the kitchen sink plumbing in the process as the pipes will be easy to access with the kitchen ripped out.