Hi I have a problem here. I have installed a belfast sink in a new utility room and I thought everything was fine until I switched on the taps and it just keeps leaking from the waste. The waste is a chrome threaded type whick fits through the hole in the sink and has a nut which is tightened below. With the waste I received 2 washers, 1 small black one which I put at the top between the basin and the plug and one larger whitish plastic one which i put at the bottom between the tightening nut and under side of basin. Whatever I do it leaks, it actually seems to leak more the more I tighten it as the washer at the bottom distorts, however I did not want to tighten too much as I thought I might crack the sink. Any ideas what i am doing wrong, any help would be much appreciated thanks Dan