We had our house remodeled 18 months ago. The drywallers may have used the utility sink for more than just water. The sink drain was clogged after words so I successfully snaked it out. Now after some grouting it is clogged again. When I used it to clean up after thinset and grout I would only wash off the tools after washing the heavy stuff outdoors. I ran the water much.
Anyway, is there a known way of removing the blockage ? It is a 3" cast iron pipe.