RFID is transfer by magnetic and electronic coupling, possessed its own nature and limitation.
Under Certain Environment, could be defect. Some resolution can take special processing to make up. Some of them can not.
LF and HF wave get few effect of Liquid environment.
But UHF will be totally blocked by it.
Human body is with liquid, when get involved, have to take consider this effect.
For personal management, could take consider our HYL20.
When baring the badge (HF RFID card) passing through, could read sensitively, no need to take consider the liquid body.
If using UHF , then have to take consider the blind zone blocked by human body.
The Principle is, leaving water the far away the better.