If it cannot be moved
The south-west is the heaviest corner and the tradition reserves it for what should not move. A pooja room here is held to be misplaced rather than harmful; the usual remedy is to shift the altar itself to the room’s north-east corner.
What the ನೈಋತ್ಯ governs
The south-west — Nairutya — is the earth corner: the heaviest, most grounded part of the plan. It is where the tradition puts what should not move, which is why the master bedroom and the structural mass belong here and water does not.
Where the ಪೂಜಾ ಕಕ್ಷ belongs
The pooja room belongs to the light half of the plan. The tradition puts it where the first sun falls and keeps it away from anything heavy, wet or waste-carrying — including sharing a wall with a bathroom, which matters more than the compass point.