This dataset contains 1-second and hourly resolution water flow rate, pressure, temperature, and electrical conductivity data collected during Test 1 of the DEMO Fracture Thermal Energy Storage (FTES) project at the Sanford Underground Research Facility (SURF) between December 10, 2024, and March 24, 2025. Measurements were taken at multiple depths and points along several boreholes, including the collar, interval, and bottom sections. Two main testing phases are included: hot water injection from December 13, 2024, to February 23, 2025, and ambient temperature water circulation from March 12 to March 24, 2025. Data is labeled with clear units, and the included documentation further details the measurement points and column labels.