If it cannot be moved
A bathroom in the south-west puts drainage under the corner that should be heaviest and most settled, which the tradition reads as leakage from the household’s foundation. The usual remedies are keeping the room dry and closed, and restoring weight to the south-west elsewhere in the plan.
What the নৈঋত্য 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 স্নানঘর belongs
Bathrooms and toilets are the rooms the tradition most wants kept away from the protected corners — not because of the compass alone but because of water, waste and the drainage that follows them. Where they cannot be moved, the remedies are about containment.