Description:Hundreds of thousands of mobile phones get dropped down the toilet every year - but this handset from Sony could be the answer. The Xperia Z can reportedly be submerged in water for up to 30 minutes. It's one of many designs unveiled at the Mobile World Congress in Barcelona. The phone has been well received by the industry and Sony hopes by offering a little extra it may even challenge the iphone. Engineer Fred Gunther.(2:09)