If a DIY solution does not work, you could call a plumber for a professional inspection. A plumber will be able to diagnose the issue correctly and will not add unnecessary repairs or replacements copper kitchen mixer tap. Once a professional inspection has been completed, the plumber will provide you with a solution. If you're not confident in your abilities, call a plumber to give you a free estimate. If the slow draining sink still does not resolve the problem, call a plumber.