Abstract: A system, apparatus and method for saliva-conductance based hydration sensors and for a wireless network comprising hydration sensors and base stations. The hydration sensors include electrodes, a means of measuring saliva conductance, a processor, memory and wireless controllers. The hydration sensors output user hydration status based on the conductance of the user's saliva. Saliva conductance is correlated with ion concentration of saliva, which is a biomarker for dehydration. Thus, saliva conductance can be a proxy for dehydration. The hydration sensors may be used in active or hostile conditions, e.g., military use. Symptoms of dehydration are delayed: fatigue and impaired judgment can occur before a user realizes he/she is dehydrated. The hydration sensors indicate dehydration to a user, thus encouraging a user to hydrate and prevent dehydration-related injuries. Data from hydration sensors may be used in determining supply delivery logistics in hostile or inaccessible terrain.