It is definitely possible to use our water meters for this purpose. The possibility of detecting a leak is dependent on the minimum flow rate of the water meter vs. the rate of flow of the leak. As our 3/4" Water Meters have the lowest minimum flow rate (1.77 ft³/hour), they have the highest probability of detecting small leaks. So provided that you are leaking at least 1.77 ft³ of water per hour, then you can detect the leak. In reality you would be able to detect a smaller leak than this but you wouldn't know how much, as the accuracy of the water meter decreases with flow rates less than 1.77 ft³ per hour.

If you want to detect leak on a 3/4" water line, the best meters to use are our NSF or High Definition (HD) models. These meters are designed to generate pulses at a high rate to provide high granularity data, when set up to read with a computer. This high granularity can provide better insights into usage patterns. In particular, it can tell you if you have a leak in your water system, because it only takes ~0.6 pints of water leakage to generate a pulse. In other words, if you see a pattern of pulses when you shouldn't (when you aren't intentionally using water) then you probably have a leak somewhere. The number of pulses over a given period of time will tell you how severe the leak is.

In addition to the water meter, the best way to detect leaks is to pair the water meter with an 
Omnimeter Pulse v.4 and EKM Push3. The Omnimeter Pulse v.4 counts pulses coming from the water meter, which equate to a specific amount of water usage. Basically what this does is digitizes the water meter's otherwise analog  data output. That digital data is then sent to the cloud by the Push3 gateway. Once the data is in the cloud you can monitor it from anywhere in the world. This allows you to detect leaks without being on site to physically monitor the water meter. The EKM Widget, shown below,
 offers one way to visualize water usage using Push3 data. It will also work on mobile devices so you can monitor your meter(s) while on the go.