Hot water scalds can be quite debilitating for a prolonged period of time. It has been previously determined that the severity of hot water scalds increases in a logarithmic trend with water temperature, which has led to legislations requiring changes to the physical environment to reduce the temperature of hot water. In September 2004, Ontario changed its Building Code, requiring all new or renovated residential buildings to lower the maximum setting of their hot water heaters to 49°C (120°F). The aim of the present study was to evaluate the effectiveness of the legislation at reducing both the overall incidence and hospitalizations caused by hot tap water scalds. Hot tap water scald cases were identified from the National Ambulatory Care Reporting System and Discharge Abstract Database databases provided by Canadian Institute for Health Information for April 2002 to March 2010. Annual incidences, hospitalizations, and outcomes were recorded. There were a total of 6952 hot tap water scald cases in Ontario, including 408 hospitalizations in the 8-year period. The average annual incidence rate for hot tap water scalds for the study period was 6.93 cases per 100,000 population and the average hospitalization rate was 0.4 cases per 100,000 population. The high-risk population group of children and elderly comprised the majority of hospitalization cases (60%); however, adults are responsible for the majority of the ambulatory cases (67%). There was a significant decrease in the age-standardized monthly ambulatory scald cases per 100,000 population after the intervention of 0.01055 (95% confidence interval [CI] [0.004, 0.017]; P = .0018) with a rate of change of 0.9455 (95% CI [0.90, 0.98]; P < .0001) and a long-term decrease of 0.19 per 100,000. There was no significant difference in length of stay of hospitalized cases after the intervention (rate ratio = 0.91; 95% CI (0.70, 1.18); P = .4624). Overall, the regulation of limiting the maximum hot water temperature in residential homes has had a positive impact on reducing the overall number of hot tap water scalds; however, they still cause a considerable amount of morbidity because the number of hospitalized cases did not change significantly. In addition to implementing regulations, active prevention and educational campaigns are still necessary to eliminate this preventable injury.