Double Bathroom Sink is very heavy, especially if you use some of the exotic stone varieties. A double sink can be connected to a single sink drain.
Install Double Sink
Put new vanity in place. Make sure the vanity is the level, and then tighten vanity to the wall controls with new screws. Place a line of sealing along the top of the vanity and place new Double Bathroom Sink in place on top of vanity. Place two new faucets in the two sets of faucet holes on the new sink. Place and tighten the crane nuts under the sink to secure the faucets.
Connect hot and cold water lines to each faucet. Connect both hot water lines from each crane to a T-pipe connection. Connect a third pipe between the hot water T-pipe coupling and the hot water tap. Connect both cold water pipes from each faucet to a second T pipe fitting. Connect a third pipe between the cold water T-pipe, fittings and cold water shut-off valve. Turn the water shut-off valves back and look for leaks. Leave existing J-shaped drainage pipes in place. Connect a T-pipe to the end of the J-tube. Tighten the T-pipe and connect the left side of the T-pipe to the left-hand sink. Connect the right side of the T-pipe to the right Double Bathroom Sink area. Tighten all connections. Test the pipes tight by running water through both sewers simultaneously. This can be done by tapping both cranes.