Our Great Lakes

Can We Drink the Water

Every day, 24 million people drink water that is drawn from the Great Lakes, treated, and delivered to their taps. Nine million more people rely on rivers, wells, and small inland lakes in the surrounding watershed. Drinking water from public systems is tested thousands of times a year to ensure that it is safe.

What is happening?

The greatest threat to drinking water safety comes from tiny microbes, including bacteria, viruses, and parasites, found in human and animal wastes. Human waste from our towns and cities is sent to sewage plants designed to destroy microbes. However, accidents and overflows caused by rainstorms can cause the release of untreated sewage into rivers and lakes. Chemical discharges from industry have been greatly reduced, but sometimes spills or leaks occur during manufacture, shipment, use, or disposal of chemicals. In some cases, people dispose of unwanted paints, chemicals, motor oil, and medicines by pouring them down household or street drains rather than taking them to hazardous waste disposal sites.

Pollution from many diffuse sources is washed into the Great Lakes by rainwater and snowmelt. In urban areas, such pollution includes spilled automotive oils and chemicals, road salt, lawn and garden chemicals, and pet waste. In rural areas, runoff from farm fields can carry manure, fertilizers, and pesticides into surrounding waters.

Modern drinking water treatment systems excel at killing microscopic organisms before the water is sent to our taps. These systems rarely fail, but when they do the consequences can be serious. In 1993, a parasite known as cryptosporidium was in the waters of Lake Michigan off the shores of Milwaukee, Wisconsin. Human error allowed the parasite to get through the city’s drinking water treatment system and into tap water. The events that took place in Walkerton, Ontario, in 2000 are worth noting here, although the community’s water was not sampled as part of the work done to prepare this report because Walkerton’s population is less than 10,000 people. Failure to chlorinate water from Walkerton wells properly allowed E. coli bacteria to contaminate the local drinking water. The incidents at both Milwaukee and Walkerton led to widespread sickness and a number of deaths.

Treated drinking water is also monitored regularly for chemical contaminants. They are rarely found in treated drinking water and, if present, are usually at levels below those that could pose a risk to human health.

What is being done?

Governments have built a broad network of protection systems to ensure that treated drinking water is safe. This safety net includes drinking water laws, regulations, and standards, source water protection plans, water quality monitoring systems, and treatment systems for both sewage and drinking water. Various information programs, including the State of the Great Lakes reports and reports from water suppliers, inform the public about the quality of their drinking water. Protecting water sources reduces the risk of exposing us to harmful contaminants, lowers the costs of treating our drinking water, and results in a healthier ecosystem in which to live. Sewage treatment systems are used to kill harmful microbes before wastewater is discharged into the Great Lakes. In the final line of defense, drinking water treatment plants use a variety of technologies to remove contaminants, for example, adding chlorine to kill bacteria and viruses before sending the water out to our faucets.

The levels of a number of toxic chemicals in the Great Lakes basin have been dropping for years due to cleanups, the imposition and enforcement of regulations, and the pollution reduction approach that many business leaders have taken. Governments, businesses, and associations have developed a range of pollution prevention programs to help companies reduce the entry of chemicals into the environment, and to help farmers keep agricultural wastes out of the water. Many local governments have developed household hazardous waste disposal programs, and many pharmacies accept unwanted medicines and dispose of them safely. Both governments and non-governmental organizations have developed public education programs on waste reduction.

Figure 1:
The water tested came from untreated drinking water sources in the Great Lakes basin or from public treatment plants supplying communities of over 10,000 people. Two exceedances occurred for total coliform, which by itself is not necessarily harmful but which may indicate the presence of harmful bacteria. No exceedances occurred for harmful bacteria, viruses, or parasites. Nitrate, a substance that can signal pollution from such sources as manure and fertilizers, exceeded limits in four instances. None of the exceedances was high enough to pose a risk to human health.

St. Lawrence River	River Water	Lake Water	Groundwater

Figure 2:
Locations of public water systems in the Great Lakes and the source from which the water is drawn.