A method for inhibiting freezing of low salinity water (H2O) in a subsea low salinity water injection flowline comprises providing the flowline with a pressure control system, which may include a high pressure pump and a pair of pressure shut in valves, which maintains an elevated fluid pressure within the flowline throughout low salinity water injection operations and shut in periods, during which periods the flowline remains filled with pressurized non frozen low salinity water (H2O) that may have a temperature of about −2 degrees Celsius.