Tyre well water ingress

As per a previous problem reported by another member I have an ongoing problem with my Range Rover in that I keep getting a small accumulation of water in the tyre well.It appears to ooze out of the seams of the metalwork of the floor pan in the area around the tyre well.I have sprayed inside the wheel arches and all around tail gate with a hose and not a drip gets in.The area under the tyre well on outside seems perfectly sealed also.None of the carpets around the well show any signs of dampness so the water is gaining access at low level.However the rear washer is nor spraying and I have atheory that it may be water laeking from the rear washer pipework that is finding it's way into the tyre well.This is apparently not a unique example of this problem and I would welcome anyone's experience or remedial suggestions for this problem before I pull my hair out!