Leakages from pipelines are low-probability but high impact events for distributors of crude/refined oil as well as drinking water. Several techniques including geological surveys, fiber optics, acoustics, pressure drop analysis and mass imbalance are in use to detect the leakages. However, all the techniques have their own drawbacks such as low sensitivity, high false alarm rate and process parameter dependencies. Pipe joints, being the most prone to leakages, have been targeted in this paper for real-time leakage monitoring. Instead of relying on indirect indicators such as vibration and pressure drop, we are proposing a new kind of microwave leak detector which can easily be clamped on a joint. The sensor utilizes a uniquely designed stripline ring resonator to detect the change in dielectric properties (caused by leakage) of a 3D printed porous substrate which is sandwiched between the two ground planes of the stripline. Main sensing element has been realized by a combination of 3D and inkjet printing. While protective clamp-style cover has been fabricated using lathe machining, 3-axis milling and wire EDM which not only protects the sensor from environmental effects such as rain but also helps avoiding false alarms. The proposed system has been validated in EM simulations as well as in measurements, which confirm that the system can not only detect the leak event but also can estimate its intensity. The measured sensitivity is better than 0.3mL which is much higher than the existing methods.