Important note: Problems caused by grade changes on neighbouring properties are generally considered to be a private civil matter.
If the neighbour has failed to provide adequate ground cover (i.e., sod, interlocking brick, etc.) in order to prevent recurrent ponding of water, unstable soil conditions or erosion, a service request can be submitted for investigation online at: http://www.toronto.ca/311, or by calling 311.
Toronto Municipal Code Chapter 629-11
Toronto Municipal Code Chapter 629-20
Under Toronto Municipal Code 629 - Property Standards, downpipes are to be properly installed for proper drainage so that no damage will be caused to any adjoining properties.
Any above-ground discharge from a downspout should be directed to discharge and be contained on the property so as to avoid damage or hazardous conditions to any adjoining property.
Important note: If water is directed to a neighbour's property, on purpose, it is a bylaw violation. Contact 311 to submit a service request for Municipal Licensing & Standards to investigate.
If there is no lengthy extension on the downpipes and the water flows there naturally, there is no violation. This may be a civil matter if damage is being caused to your property by natural flow.