MPH 530 Module 3 Water Quality and Waterborne Disease Example

Safe From the Tap: Lessons From Milwaukee on Drinking Water and Waterborne Disease

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Master of Public Health Program, Aspen University

MPH 530: Environmental Issues in Public Health

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Month Day, Year

Safe From the Tap: Lessons From Milwaukee on Drinking Water and Waterborne Disease

Safe drinking water is one of public health's greatest achievements, yet it is easy to take for granted. When treatment fails, the consequences can reach hundreds of thousands of people within days. This paper examines drinking water quality and waterborne disease through the 1993 Milwaukee Cryptosporidium outbreak, places it in the context of the current national burden and outlines improvements for a composite utility.

The National Burden

Waterborne disease remains common, and lead from pipes, as Flint showed, is only one of the threats water can carry (Hanna-Attisha et al., 2016). A national estimate for 17 waterborne infectious diseases found about 7.15 million illnesses each year, leading to 601,000 emergency department visits, 118,000 hospitalizations and 6,630 deaths, with direct health care costs of $3.33 billion. Most hospitalizations and deaths were caused by pathogens that grow in biofilms inside pipes, such as Legionella and nontuberculous mycobacteria (Collier et al., 2021).

The Milwaukee Outbreak

In the spring of 1993, the turbidity, or cloudiness, of treated water at one of Milwaukee's two treatment plants rose sharply from March 23 until the plant was shut down on April 9. Cryptosporidium oocysts were found in ice made in the affected area during those weeks, and laboratories recorded a more than 100-fold increase in cryptosporidium isolations. Illness typically lasted a median of nine days, with watery diarrhea in 93% of confirmed cases (Mac Kenzie et al., 1994). An estimated 403,000 people became ill, the largest waterborne outbreak in US history.

Why Treatment Failed

Cryptosporidium is a parasite whose oocysts resist chlorine, so removal depends on coagulation, settling and filtration. Heavy runoff from spring rains carried contamination into Lake Michigan near the plant's intake, and changes in the coagulant and plant operations reduced filtration effectiveness. Turbidity readings rose, but the water still met the standards of the time, and no one tested patients for the parasite routinely.

The Multiple Barrier Approach

Modern water safety relies on several barriers, so that if one fails others still protect the public. The table summarizes them.

Surveillance Signals

In Milwaukee, the first signals came from outside the water system: pharmacies reported surging sales of antidiarrheal medicines, and schools and nursing homes reported absences and illness. Today, syndromic surveillance of emergency visits and pharmacy sales, combined with rapid communication between utilities and health departments, aims to catch such signals within days.

Regulatory Changes

After Milwaukee, federal rules were strengthened to require tighter turbidity limits, better filtration performance and, for systems at higher risk, additional treatment such as ultraviolet light or ozone that inactivates Cryptosporidium. Utilities also increased monitoring of source water for the parasite.

Pathogens in Pipes

The shift in the national burden toward biofilm pathogens reflects aging pipes and plumbing in large buildings, where warm water and low disinfectant allow Legionella to grow. Legionnaires' disease outbreaks linked to hospitals, hotels and cooling towers have led to water management programs that monitor temperature and disinfectant levels in building plumbing.

Private Wells

About one in eight Americans relies on a private well that is not regulated under federal drinking water law. Well owners are responsible for testing, and many never test. Contamination with bacteria, nitrates from agriculture or naturally occurring arsenic is common in some regions. Health departments can offer free or low-cost testing and education, particularly after floods. Testing once a year for bacteria and every few years for nitrates and arsenic is a common recommendation, with extra tests after flooding or changes in taste or smell.

A Composite Utility Improvement Plan

A composite utility drawing from a river downstream of farms and a city plans several steps: continuous turbidity monitoring at each filter with automatic alerts; ultraviolet treatment as an additional barrier against Cryptosporidium; a source water protection partnership with farmers to reduce runoff; a written agreement to notify the health department within one hour of any treatment failure; and a joint surveillance plan tracking emergency visits for diarrheal illness.

Communicating With the Public

When treatment fails, utilities issue boil-water advisories or do-not-drink orders. Messages must reach everyone, including people with weakened immune systems, who face the greatest risk from Cryptosporidium. In Milwaukee, deaths occurred mainly among people with AIDS. Plans should include targeted outreach to clinics serving immunocompromised patients.

Nitrates and Agriculture

Chemical contaminants also matter. Nitrate from fertilizer and manure can enter groundwater, and high levels in drinking water can cause methemoglobinemia in infants. Agricultural regions with shallow wells face the greatest risk, and source water protection programs work with farmers to reduce runoff.

Equity in Water Safety

Small water systems, often in rural or low-income communities, have fewer resources for treatment upgrades and trained operators, and they account for many health-based violations. Tribal communities and colonias along the southern border may lack piped water altogether. Funding and technical assistance for small systems are equity measures.

Climate and Water

Heavy rainfall events, becoming more frequent with climate change, increase runoff and the risk that treatment plants will be overwhelmed, as happened in Milwaukee. Drought concentrates contaminants and can force utilities to switch sources. Water safety planning now includes climate projections.

Role of the Health Department

Health departments investigate suspected waterborne outbreaks, advise utilities on public notification, test private wells and track diarrheal illness. Formal agreements with utilities specify who notifies whom, how quickly and what data are shared, so that both agencies act within hours rather than days.

Conclusion

The Milwaukee outbreak showed how a failure in one barrier, combined with weak monitoring and surveillance, could sicken hundreds of thousands. Today's burden of waterborne disease, much of it from pathogens in pipes, shows that water safety demands constant attention. Multiple barriers, real-time monitoring, strong links between utilities and health departments and attention to private wells and building plumbing protect the public.

References

Collier, S. A., Deng, L., Adam, E. A., Benedict, K. M., Beshearse, E. M., Blackstock, A. J., Bruce, B. B., Derado, G., Edens, C., Fullerton, K. E., Gargano, J. W., Geissler, A. L., Hall, A. J., Havelaar, A. H., Hill, V. R., Hoekstra, R. M., Reddy, S. C., Scallan, E., Stokes, E. K., ... Beach, M. J. (2021). Estimate of burden and direct healthcare cost of infectious waterborne disease in the United States. Emerging Infectious Diseases, 27(1), 140-149. https://doi.org/10.3201/eid2701.190676

Hanna-Attisha, M., LaChance, J., Sadler, R. C., & Champney Schnepp, A. (2016). Elevated blood lead levels in children associated with the Flint drinking water crisis: A spatial analysis of risk and public health response. American Journal of Public Health, 106(2), 283-290. https://doi.org/10.2105/AJPH.2015.303003

Mac Kenzie, W. R., Hoxie, N. J., Proctor, M. E., Gradus, M. S., Blair, K. A., Peterson, D. E., Kazmierczak, J. J., Addiss, D. G., Fox, K. R., Rose, J. B., & Davis, J. P. (1994). A massive outbreak in Milwaukee of Cryptosporidium infection transmitted through the public water supply. New England Journal of Medicine, 331(3), 161-167. https://doi.org/10.1056/NEJM199407213310304