Drainage By-Law

Recognizing that a changing climate is likely to bring more incidents of intense rainfall in the future, The City of Edmonton took the initiative to ensure that newly-developed lots are designed with grading to reduce the impact of rainfall-induced flooding. By legislating that a positive slope (the degree of which is dependent on the surface material) exist in all newly-developed lots, rainfall will be drained away from housing foundations and reduce the likelihood of basement flooding. This has been on ongoing process that, at its onset, met substantial political resistance but has persisted for decades and is evidence that climate adaptation is an iterative process that needs constant improvement and adjustment over the years.

Understanding and Assessing Impacts

Lot grading is the simple concept of creating a slight slope at the base of a home. This prevents rainfall from pooling at the edges of a house, which would then run the risk of seeping into the basement through cracks in the foundation, basement walls, or below-grade windows. Additionally, this kind of water pooling can contribute to stress on the municipal sewer system and lead to sewer backup flooding as well; which can be particularly damaging in a combined sewer system as household sewage from the entire neighbourhood can backup into a house’s basement. As climate change is expected to increase both the frequency and magnitude of high-intensity precipitation events, small but widespread changes such as effective lot grading can save many people from the hassle and expense of basement flooding. Edmonton has had in place a forward-looking and progressive flood reduction strategy since at least the 1980’s. The city has also enjoyed a strong and positive working relationship with surveyors, builders, and developers. This allowed for the City to work with those groups to create a lot grading enforcement strategy that is acceptable to all parties while still increasing the protection and resilience of Edmonton homes.

Identifying Actions

Edmonton is recognized for having a history of proactive and forward-looking bylaws regarding protecting homes from basement flooding. For example, the city first mandated the installation of backwater protection valves in 1989. The lot grading by-law came about as a request by surveyors, developers, and builders for a standardized and predictable approach to managing lot grading. This process began sometime in the mid-1980’s, and by 1988 the city had assembled a team with the planning office to look into creating a standardized lot-grading bylaw. This effort was initially met with substantial skepticism by homeowners, who felt that this process would result in an increase in home ownership costs. While that may have been true originally, these costs are now an expected part of home development and can therefore be predicted and budgeted for.


The lot grading requirements were first introduced as part of the Minimum Property Standards bylaw in 1989. A rewrite of the Buildings bylaw in 1993 passed the costs of lot grading approval on to prospective homeowners (which saw some resistance, but it was ultimately passed). The 1997, the official Surface Drainage By-Law came into effect. This was later updated and consolidated into the Drainage Bylaw in 2013. This process highlights the fact that resilience is a process that needs constant upkeep and innovation as new technologies develop and a greater understanding of the hazards a city faces is gained.

Outcomes and Monitoring Progress

In recent discussions with city employees, it would appear that the original homeowner resistance to the extra development fees has dried up and people have normalized the process and accepted it as the standard state of affairs. One of the important lessons learned here is that a municipality can benefit from having strong relations with the development and buildings industry as that allows new legislation to be developed in a way that is palatable to all concerned parties while still achieving the desired results. The political necessity of having strong partnerships should not be discounted.