Can the owner of a building, who served as his own general contractor, be sued for a construction defect by a subsequent owner.

In theory, yes you could be sued. You would have to bring claims against all of yoru subcontractors. I suggest that you speak to an attorney near you asap.

They are more likely to claim that you did not disclose the water damage when the property was sold. However, if you are sued for the construction, you will want to tender the defense to your insurance company to insure you do not waive policy notice requirements. Do not assume that you do not have coverage for a construction defect. The standard CGL policy has a subcontractor exception to the "Your Work" exclusion. In other words, if one of your subcontractors messed up and caused the defect you likely have coverage and your insurer has a duty to defend. This is a very nuanced area of the law, however, so you will want to consult an attorney that has construction and insurance expertise.