During the H-mode experiments with ICRF heating on JET it was observed that the influxes of deuterium and impurities can substantially modify the quality of both the energy and particle confinement. In particular a Low Particle Confinement(LPC) H-mode was triggered either by deuterium input into the X-point region or as a result of a moderate impurity influx into the plasma boundary. In the LPCH-mode the particle confinement is at least 3 times less than in a normal Hmode. The energy, on the other hand, decreased by only 20%. The electron density, the deuterium density and the radiated power are also less than in a normal H-mode. However thdeuterium dilution reaches a steady-state. The H-mode duration is extended by the LPC-phase to 2.8s and is limited only by the length of the heating pulse. The LPCH-mode particle confinement is linked to Lmode like particle diffusion within the radius 0.5<r/a<<0.8 and the H-mode like barrier due to large V/D in the plasma boundary. This mode has the potential for substantially extending the H-mode phase to make it more reactor relevant.