The negative thermo-optic coefficient of water has been used to fabricate an athermal Bragg grating device. Glucose was used to modify the refractive index of water, allowing this response to be tuned to the desired operating temperature range. Over a 10??C temperature range the Bragg response was found to vary by 3.7 pm, an improvement of nearly two orders of magnitude over the unetched Bragg grating. The low cost of fabrication compared to traditional athermal Bragg devices makes them ideal for incorporation within integrated photonic networks.