Pocketnow reports that, like the rest of the Galaxy S5 line, the Mini will have waterproofing. It is assumed that the dust and waterproofing rating will be IP67, the same as the rest of the S5 line thus far.
IP67 rating means that the phone should not be submerged in water for more than 30 minutes, nor should it be submerged at a depth greater than one meter.
2. Samsung Galaxy S5 Mini May Lack Heart Rate Monitor, Fingerprint Scanner