The under sink filter we purchased with our newly constructed home works well when it is not leaking. The problem is that the threads on the case that houses the carbon block filter do not provide a watertight seal, the watertight seal is provided by the o-ring that is installed on top of the carbon block filter. The o-ring provides a seal as long as the water pressure is maintained. As soon as the pressure is reduced, the housing leaks.
This is especially problematic when installed with a whole house leak detection system that shuts off the water in the house whenever a leak is detected. The leak, e.g., a toilet valve that occasionally sticks open, combined with the water being shut off results in reduced pressure, which results in a leak at the filter housing. When the leak is found and corrected and the whole house leak detection system is reset, the filter housing will again leak until water pressure is back to normal.
I would not recommend this under-sink filter system when used in a house with a whole house leak detection system. read more