The potential for health risks from intrusion of contaminants into the distribution system from pressure transients.
The potential for public health risks associated with intrusion of contaminants into water supply distribution systems resulting from transient low or negative pressures is assessed. It is shown that transient pressure events occur in distribution systems; that during these negative pressure events pipeline leaks provide a potential portal for entry of groundwater into treated drinking water; and that faecal indicators and culturable human viruses are present in the soil and water exterior to the distribution system. To date, all observed negative pressure events have been related to power outages or other pump shutdowns. Although there are insufficient data to indicate whether pressure transients are a substantial source of risk to water quality in the distribution system, mitigation techniques can be implemented, principally the maintenance of an effective disinfectant residual throughout the distribution system, leak control, redesign of air relief venting, and more rigorous application of existing engineering standards. Use of high-speed pressure data loggers and surge modelling may have some merit, but more research is needed.
LeChevallier
Mark W
MW
American Water, 1025 Laurel Oak Rd, PO Box 1770, Voorhees, NJ 08043, USA. mlecheva@amwater.com
Gullick
Richard W
RW
Karim
Mohammad R
MR
Friedman
Melinda
M
Funk
James E
JE
D003343:Corrosion; D004784:Environmental Monitoring / Q000379:methods; D005618:Fresh Water / Q000737:chemistry; D006801:Humans; D018570:Risk Assessment; D012307:Risk Factors; D014481:United States; D014874:Water Pollutants, Chemical / Q000009:adverse effects*; D014881:Water Supply / Q000592:standards*
D014874:Water Pollutants, Chemical