What did people use as a sink in the 1700's?
A bucket of their own urine.
They used wash basins. Basically a large shallow bowl. They even had special tables to hold them.
A wash-basin. The wash basin be made of porcelain or clay pottery, depending on the wealth of the owner, and it would reside on a wash-stand that would hold the basin in a recess, and would hold a pitcher of water below, and a small spindle to hold a towel.