Baltimore Warns Residents of Microbial Contamination in City Drinking Water

The parasite, cryptosporidium, is considered a health risk for those who are immunocompromised, such as the elderly, transplant patients and those with HIV.

The City of Baltimore is warning residents about a potentially dangerous parasite, which has been detected in drinking water supplied to some residents.

The microbial contamination warning was issued by the Baltimore City Department of Public Works (DPW) on Thursday, indicating that cryptosporidium has been detected at low levels in its Druid Hill reservoir. The reservoir supplies a significant portion of the city’s drinking water to parts of Baltimore and the cities of Towson, Timonium and Parkville.

Cryptosporidium is a parasite often found in lakes and rivers. It can cause gastrointestinal problems such as diarrhea, nausea and stomach pain. It can be particularly dangerous for those who are immunocompromised, such as individuals with HIV, cancer, or those with a depressed immune system, such as individuals who recently underwent organ transplant surgery.

The city’s warning indicates that the levels of cryptosporidium detected in the reservoir were low and said the general public has little to fear.

“The levels of Cryptosporidium detected in our water supply indicate a low risk for the general population,” the warning states. “This means that for most people, the water is still safe to drink. However, vulnerable populations should consider taking precautions.”

Druid Lake, the affected reservoir, is uncovered, and thus the U.S. Environmental Protection Agency (EPA) requires Baltimore to sample for cryptosporidium and giardia on a regular basis at its uncovered reservoirs. Testing on Druid Lake is expected to be finished by December 30, and testing of the city’s other uncovered reservoir, Ashburton, will be completed by November 30.

The latest warning came after an analysis of testing samples collected from Druid Lake on September 19. The city will continue testing the water more frequently until “it can reliably show that Cryptosporidium is not detected” the warning indicates.

Baltimore Drinking Water Recommendations

Baltimore DPW indicates most residents do not need to take any additional precautions unless they are immunocompromised. Those who are more vulnerable to the parasite are advised to:

• Drink bottled water
• Boil water for one minute before consuming
• Filter tap water using filters labeled to ANSI/NSF 53 or 58 standards, or a filter designed to remove objects 1 micron or larger.

A full map of the affected areas is included in the city’s drinking water warning.