The treatment well tiltmeter system comprises one or more tiltmeter assemblies which are located within an active treatment well. The treatment well tiltmeter system provides data from the downhole tiltmeters, and can be used to map hydraulic fracture growth or other subsurface processes from the collected downhole tilt data versus time. The system provides tilt data inversion of data from each of the treatment well tiltmeter assemblies, and provides isolation of data signals from noise associated with the treatment well environment. As well, the treatment well tiltmeter system provides geomechanical modeling for treatment well processes.