[2] In compliance with IP5/7 and IP5X, Xperia Z is protected against the ingress of dust and is water resistant. Provided that all ports and covers are firmly closed, the phone is (i) protected against low pressure jets of water from all practicable directions in compliance with IP 55; and/or (ii) can be kept under 1 metre of freshwater for up to 30 minutes in compliance with IP 57. The phone is not designed to float or work submerged underwater outside the IP55 or IP57 classification range and should not be exposed to any liquid chemicals. If liquid detection is triggered on the handset or battery, your warranty will be void.
Sony Mobile 官網上自己寫的。上面說可以1米以內淡水30分鐘可以防水(IP57),超過這個標準,就失去保固。