The glass is very unlikely to break. The house is available from the same company that designed and built an underwater resort. The glass is specifically engineered for it's purpose, and is surely incredibly thick. Short of a bullet hole from a very large caliber weapon, I wouldn't worry about it. About an hour from here there is the Oregon Coast Aquarium, and a place called undersea gardens. Same thing, submerged levels completely surrounded by the ocean around them. Not once has there been a leaking/breaking issue, and they've been around for decades.
