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1. I have installed a backwater valve, have a sump pump, and good lot grading, but I still get flooded. Why did this happen?

The specific reasons for a home to experience flooding have to be investigated on a case-by-case basis. Possible causes could be foundation wall seepage, failure of a backwater valve or sump pump, excessive flows the sump pump cannot handle, and/or excessive street flooding.

2. The downspout from my eavestrough is connected to the sewer pipe. Should it be disconnected?

Yes, The town's sanitary sewer system is not designed to handle the additional burden of stormwater. 

3. What is the importance of good lot grading?

Good lot grading keeps surface water away from your home and your weeping tile system. Ideally a lot should be sloped steeply away from the home in a way that allows surface water to flow onto town property (e. g. , streets and lanes), rather than onto a neighbouring property. A disconnected downspout and sump pump should discharge at least 15 feet away from the home to ensure water does not seep down the side of the house and into the home's weeping tile. 

4. How does stormwater flooding cause my sanitary sewer to back up? Are there not two separate drainage systems?

Because sanitary sewers are not watertight, stormwater can get into the sanitary sewer in a number of ways:

• at manholes, through manhole covers, and through cracks and voids around the manhole
• from the surrounding ground, through cracks or separations in the sewers and from private service connections
• from weeping tile (foundation drainage) systems at private homes and buildings, since poor lot grading contributes to weeping tile flows
• from downspouts that have been incorrectly connected to the sanitary sewer system rather than the storm sewer system.

Also, during larger storm events, much more water pools on the surface than normal. This can cause an increased amount of water to enter the sanitary sewer.

5. How can I stop flooding on my property (yard or basement) caused by discharge from my neighbour's downspout or sump pump?

Check your own lot grading. Most homes over five years have settlement around the foundation walls. Remember, downspouts only pick up roof drainage. If both houses have proper slope away and proper drainage swales then the discharge of the downspout and/or sump pump would be directed off the lot. Have you ever considered where your surface runoff would go if your neighbour's house was not there?

6. I live in an older neighbourhood. My neighbour has built a new house with a higher surface elevation than surrounding properties. Are there set standards for drainage elevation, and what should I do?

A new house built in an older area is called in-fill housing. In these cases, the builders must conform to the provisions of the Property Drainage Bylaw and the Development Standards and Procedures, which prohibits drainage onto adjacent properties. Matching the existing grade at the common property line is normal practice for these developments. Adjacent homeowners must consider their own grading. 

They should be aware that under the Property Drainage Bylaw and the Development Standards and Procedures, new homes are required to have a 5% slope away from the foundation walls.

7. My neighbour's re-graded lot is higher than mine. What should I do to prevent flooding on my property?

Check your own lot grading and foundation drainage. Then speak with your neighbour. Remember, surface water will follow the grade of least resistance. If you have a poor or negative grade, the surface water will flow towards your foundation wall increasing the risk of basement flooding.

8. My neighbour's new sidewalk is at a higher elevation and water runs into my yard. What should I do?

Effective side-lot drainage requires the co-operation of both property owners. Check your own lot grading and foundation drainage, then speak with your neighbour. Ask them if they can construct a retaining wall to catch the surface drainage, or re-direct the downspout discharge or sump pump discharge to force the surface drainage to flow toward the front street or back lane.