It is the tenant’s responsibility to keep your windows clean.
Periodically clean the inside and outside of the glass and hose off the screens.
Please make sure to check both the inside weep-hole and outside weep-hole in your windows. They might be clogged with dust (inside) and leaves and spider-webs (outside) and might be preventing water from passing through.
How can a homeowner help prevent mould growth on window frames or liners?
When you close your blinds, do not close them tightly and do not drop the blinds all the way to the bottom of the window liner; leave the blinds up slightly to allow for air-flow.
For those of you that have curtains or drapes, leave the curtains or drapes up slightly to allow for air-flow.
In the winter particularly, when it’s cold outside and warm inside, windows will naturally condensate – take the time to dry each and every window frame; and on a bi-weekly basis, clean the window frames and corners with white vinegar (1 part vinegar to 2 parts water). Leave windows open slightly to allow for additional air-flow.