Municipal wastewater is a complex mixture of human waste, suspended solids, debris, nutrients, pathogens, toxics, and a variety of chemicals that are washed down the drains and toilets of residences, businesses and industry. Municipal wastewater is also a source of endocrine disrupting substances, pharmaceutical, personal care products, and other contaminants. 

Through the hydrologic cycle, natural landscapes, such as forest, fields, and wetlands, allow rainwater and snowmelt to slowly percolate into the ground, which then recharges the groundwater table. In contrast, urban surfaces such as paving, buildings, and stoned walkways prevent water from filtering into the ground. As a result, water remains on the surface, accumulates, and runs over the surface creating the potential for flooding and erosion.

Landfill Site. Source: D'Arcy NormanCompared to garbage dumps of the past, landfill sites today are highly engineered.  Landfill bottoms are lined to prevent contaminants from seeping or leaching out and leachate is collected and then discharged to a sewage treatment plant or treated on-site before being discharged to a waterway. However, it was only recently that regulations have required fully enclosed landfill liners, leachate collection and treatment, landfill buffer areas and surface water control.

Road SaltCanadian road authorities and citizens use huge amounts of road salts to melt snow and ice in the winter. During the winter of 1997/98, an unusually mild winter with lower than average snowfall, five million tonnes of road salts were spread on roads in Canada. The salt melts the snow, which then runs off roads and other surfaces, carrying some of the salt with it. Together with the melted snow, the chemicals that make up the salt can seep into the ground or be carried into nearby streams, ponds and rivers.

In Canada, we are very fortunate to have modern water treatment and distribution systems. Many good things have resulted from these systems, including the virtual eliminationof serious waterborne diseases such as cholera and typhoid in Canada. Our methods of water treatment and distribution have been described as among the major health-related advances of the past century.

Some municipal wastewater effluents and sources of water have even been found to contain very small amounts of pharmaceutical drugs such as aspirin, ibuprofen, antacids, birth control, anti-inflammatory, and anti-psychotic drugs. The problem arises with the natural functions of the body, which only absorb a small portion of the drug, while the rest of it will pass through the body to be flushed away into wastewater systems. Municipal wastewater treatment facilities are not designed to remove these substances.