During winter, wall and floor tiles in bathrooms and showers take longer to dry out. In cold weather just leaving the tile surfaces to dry out on their own is very likely to result in mould growth. Left unchecked, the mould will not only look unsightly but may even damage the grout joints and cause water penetration. Leave windows open until the room is dry. Clean the tile surfaces regularly to kill the mould spores, but don't use a strong bleach solution as this is likely to damage the grout.
Tenants are responsible for looking after the home and keeping it in reasonable condition.
This means that tenants must take reasonable steps to ensure condensation and mould growth are kept to a minimum. Under the circumstances, it's up to the tenant to make certain the home is kept properly ventilated and dry. Of course, in some cases it's unreasonable for landlords to expect tenants to cope with severe condensation problems without some help. Property owners should therefore take reasonable precautions before offering a home for rent, not only to prevent disputes but also to protect their investment. Fit locks to all windows so they can be left slightly open, to permit cross ventilation.