I have a basement laundry sink that is currently connected to a very old (probably galvanized) drain pipe that is buried beneath the basement floor. This pipe will not stay unclogged. There is another much newer (PVC) drain line that currently services the house's bathroom (both the tub/shower and the bathroom vanity drain through this line). This drain pipe runs vertically about 3 feet from the basement laundry sink. I'd like to cap-off the old drain line and connect the laundry sink to this newer PVC drain line. Is there any reason why I shouldn't connect the basement laundry sink to this 1.5" PVC drain line? Will a 1.5" PVC drain adequately service a tub/shower, bathroom vanity, and a laundry sink? The washing machine also empties into this laundry sink.