First Person Controller goes past through elements

I've got such situation.

There's water: BoxCollider (isTrigger = true).
There's podium: BoxCollider (isTrigger = false), Rigidbody (useGravity = false; isKinematic = true; constraints = ALL).
There's First Person Controller: BoxCollider (isTrigger = false), Rigidbody (useGravity = true).
There's sphere: SphereCollider (isTrigger = false), Rigidbody (useGravity = true).

Water is there. Podium is half under water layer, the other half is above it. Both FPC and sphere are ON podium.

Sphere is just there, staying on podium. But FPC, flickers between two localisations about 1.5 meter from one another. If I click on in-game editor, FPC just slowly goes through the podium, when I go into podium with my editor camera (by going through it's walls), as soon as FPC touches water, it doesn't go through podium anymore, but moving it still makes FPC flicker of it's position.

Instead I hoped that I would be able to push sphere to water and let it go through. Any help ?

@Edit - Found out that if you press Space all the time, player becomes Superman.