After printing a reed-holder for our gas meter (Kromschröder G4) and intensively looking on my other meters, I found a rubber insert in my Zenner MNK water meter as placeholder for a reed contact. Since the manufacturer offers the required part with loose wires for ~35€ I was looking for a cheaper version - finally had to create one on my own.
To fix the reed tube inside I would recommend to place it on a piece of masking tape, insert some hot glue and push the reed tube to the bottom. After soldering fill up with hot glue as cable relief.
Be careful when screwing! I shortend my 2,5x12mm to approximately 6mm. If you crack the acrylic cover the meter will start leaking!