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Improving Drainage


Improving Your Property's Drainage

What is drainage?

Drainage removes water from an area. Proper drainage makes sure that water flows away from the walls of your home or building. It can help reduce the risk of flooding, damage, erosion or wet areas.

Improving Drainage

The ground around your building should slope away from your foundation. Roof downspouts should extend two metres away from the sides of a building and be angled to direct stormwater away from your foundation and your neighbour's property.

Always ensure that leaves and other debris do not block eavestroughs, downspouts, ditches or storm drain inlets on your property or the street. Blockages lead to water ponding and can be a cause of flooding.

The best time to learn how your property drains is when it's raining. Watch where the water goes and where it collects. You may be able to see where drainage can be improved.

The city's stormwater drainage system is designed to collect stormwater from private and public properties across the city.

In the right amounts and places, stormwater on your property can be good for lawns and gardens. Stormwater drainage that uses water to keep plants healthy is called green infrastructure. Green infrastructure (trees, raingardens and wetlands) can be beautiful and fun.

Use the tabs above to find out ways to improve your property.

Green Infrastructure for Residential Property

Before you can use the infrastructure options listed below, you'll need to look at the drainage from your roof. You'll need to ensure that this drainage has a safe place to go if you disconnect your downspouts from the City storm drainage system. In the case of raingardens or soakaway pits, a safe place to release that rainwater would be at least 6-10 feet from your foundation and away from neighbouring properties. A rainbarrel can be located next to your foundation but the overflow hose should also be directed at least 6 feet away from your basement walls and other properties.

Rain barrels

Rain barrels can be placed at the end of the downspout from your roof to collect rainwater and reduce the amount of stormwater draining from your property. Water collected in the rain barrels can be used to water your garden or lawn, helping you conserve water and save money.

Soakaway pits

A soakaway pit, also called a dry well, is an underground pit filled with stones and lined with landscaping fabric to let stormwater soak into the ground faster.

Rain gardens

Rain gardens are attractive, planted low areas for collecting stormwater. To make one, the soil is dug out and replaced with a layered mix of gravel, sand and compost. The gardens are made with a variety of plants that can be flooded after rainfalls but don't need to be watered when it's dry.

Because rain gardens require digging, it is important to know what's in your soil and where utility lines are buried before you start any work. Contact before you dig and keep any digging at least three metres (ten feet) away from any foundations. Also ensure that any overflow has a safe place to go and doesn't cross sidewalks or into neighbouring properties.

Permeable pavement surfaces

Porous concrete and asphalt that water can drain through is available for driveway and parking surfaces. These are made with a different mix of materials than regular concrete and asphalt. Precast paving stones designed to allow water to drain into the ground are also available.

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Green Infrastructure for Commercial Property

Green development standards

The City's Green Development Strategy focuses on sustainability and promoting environmental responsibility in new development in Mississauga. To learn more on the City’s Green Development Standards, click here.

Rainwater harvesting

Rainwater can be collected or harvested. Large scale rainwater harvesting works, like rain barrel water collection on a residential property, only on a larger scale. Rather than using barrels to harvest rainwater that runs off of catchment areas (like your roof or parking areas), Storage Tanks or Cisterns are more suitable for large properties. Some of these systems can hold tens of thousands litres of water.

Cisterns can be installed both indoors and outdoors and the water can be used for irrigation on your property or even for flushing your toilets. Contact licensed professional services and get all approvals to install large cisterns.

Bioretention facilities

These structures collect, store and filter stormwater runoff, like a rain garden. Like rain gardens, bioretention areas are shallow dips in the ground that are filled with permeable soil, flood tolerant plants, stone and wood chips. Bioretention is the process where contaminants and sedimentation are removed from stormwater runoff. Stormwater is collected into the treatment area which can be a grass area, sand bed, ponding area or mulch layer, planting soil, and plants. The main differences are that bioretention areas are usually larger than rain gardens on a residential property and a bioretention area may also have drains beneath it for drainage. If there is no drain beneath a bioretention area, and soil conditions allow it, collected stormwater is filtered into the ground.

They can be built into a lawn area or around parking lots, raised landscaping planters, extended tree beds and in islands surrounded by paved or concrete surfaces.

Soakaway pits (dry wells), infiltration chambers and trenches

Large underground soakaway pits on commercial properties work the same way that they do on residential properties. Infiltration chambers and trenches are like soakaway pits in that they create space underground to collect rainwater for it to soak slowly into the ground. Infiltration chambers are large plastic, open-bottomed devices with perforated sides that are generally found beneath parking lots or other impervious areas. Their purpose is to temporarily store stormwater runoff from the site and filter into the ground beneath a sizeable hard surface area.

Infiltration trenches are similar to infiltration chambers, with the main difference being that they are long and narrow. These are often installed alongside or beneath walkways, sidewalks and narrow patches of land between buildings where there is enough distance from the building foundation.

IMPORTANT: Stay within your property's limit

When making improvements or changes to your property, it is important to stay within your property's limit and not extend onto public property, ravines or your neighbor's yard. Encroaching on City property can interfere with drainage, City maintenance or limit the use and enjoyment of public property. You could be fined by the City. Learn more here.

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