Drain For Flat Bottom Sink . Offset drains make your sink more accessible from top to bottom. To unclog a drain, bring a pot or kettle of water to a vigorous boil. 14" Girard Hammered Copper Drum Sink with Flat Bottom Bathroom from www.signaturehardware.com Drain placement provides more usable space on the bottom of the sink and in the cabinet below. A sloped curve makes draining the sink easy. Andreky_popov / shutterstock.com to plunge a toilet.