Most embedded antennas will not function well on PCB length less than 95mm. That being said some carriers allow for reduced TRP and TIS requirements on small devices so some reduction in radiated performance can be tolerated. It would be hard to recommend a particular antenna not knowing how much available board space you have available for the antenna. An antenna in a water meter would more than likely be placed either at or below the ground surface so we would need to know how far away the ground surface is away from the antenna (10cm to 20cm is preferred). Would the housing be placed on a metal or plastic cover? If placed on a metal cover, there would need to be at least 15mm to 20mm of metal clearance between the antenna and the meter cover. We have success using our Lucida antenna PN: SR4L002 but have recently released an antenna that will work on a shorter ground plane called the Pharaoh antenna PN: SR4L073. The Pharaoh antenna has not been integrated into a water meter design but functions very well on short ground planes such as yours. If you are interested in our help with integrating one of our antennas into your design please contact our tech support email at email@example.com and we will put you in touch with our Antenna Application Specialists.