My baby has bitten through a cooled teether. Will this do harm? 21 November 2019 11:11 Updated No. Difrax uses distilled water in the teether, which is harmless to your baby. However, it is wise to replace the teether. View our range of teethers and teething toys here. Related articles Do I need to boil pacifiers? How long will it take before my package will be delivered? How long does it take for the bottle contents to heat up? How do I clean the Difrax microwave steriliser?