Dr. Sharon Roy reviewed the waterborne outbreaks in Carrollton, Ga., in 1987 and in Milwaukee in 1993, noting that they made clear the need for improved disease surveillance and coordination between public health agencies and water utilities, as well as the need to regulate Cryptosporidium in drinking water. The outbreak investigations uncovered a series of circumstances leading to thousands suffering gastrointestinal illness:
- heavy precipitation
- contamination from raw or treated sewage
- disruptions in normal monitoring and plant operations
- recycled filter backwash water
During the H2Open forum, Roy noted five trends in disease outbreaks:
- The number of outbreaks has decreased because of the Safe Drinking Water Act and the additional drinking water regulations;
- Pubic systems account for a decreasing proportion of outbreaks;
- There is a decline in outbreaks from systems using surface water;
- For the first time, Legionella, rather than gastrointestinal disease, is the cause of a majority of outbreaks; and
- Public health officials are discovering an increasing number of deficiencies in premise plumbing and point-of-use devices.
Although premise plumbing is not under the control of water utilities, it may behoove them to be involved, said panel moderator Mark LeChevallier (American Water). Utilities could support changes in plumbing codes that would do more to address premise plumbing deficiencies.