Update: No traces of the parasite cryptosporidium were found in a water sample taken from the Druid Lake Reservoir, the Baltimore City Department of Public Works said Tuesday Oct. 3. The clean bill of health came five days after the department said it had discovered low levels of cryptosporidium, or crypto, in the open-air reservoir that supplies drinking water for parts of Baltimore City and Baltimore County, as well as Howard County.

The Baltimore City Department of Public Works late last week announced low levels of the parasite cryptosporidium had been detected in Druid Lake Reservoir, an open-air reservoir that feeds into the water supply for parts of Baltimore City and Baltimore County, as well as Howard County.

The parasite is known to cause gastrointestinal issues, especially in older people, children and those with weakened immune systems. The department on Saturday said the detection advisory “remains in effect until further notice.” For most people, though, the water is safe. Here are some answers to commonly asked questions.

What is cryptosporidium?

Cryptosporidium, or “crypto” for short, is a parasite found in water that can cause an infection called cryptosporidiosis. Cryptosporidiosis can cause diarrhea and other gastrointestinal issues but “is normally not a serious disease in healthy people,” according to Johns Hopkins Medicine.

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How did city officials detect the parasite? And where is it?

The cryptosporidium was detected in the Druid Lake reservoir in a routine testing sample that was collected on Sept. 19, according to city officials, and laboratory results were reported on Sept. 26.

Druid Lake Reservoir, like the Lake Ashburton Reservoir, holds water that has already been treated for consumption. City officials said that because such a low level was detected, it is not possible to determine a source of the parasite. This past weekend, DPW said that recent monitoring indicates that source water — obtained from the Liberty, Loch Raven and Prettyboy reservoirs — is not affected by crypto. As part of its regular filtration process, DPW treats source water for crypto before the water is delivered to its finished reservoirs.

The water was tested again on Sept. 27, but officials said it could be another week before those results came back.

On Sept. 28, DPW publicly reported the presence of the parasite in the drinking water based on the Sept. 26 test result. In the update shared this past weekend, DPW did not explicitly say why it did not share the test results when the agency received them on Sept. 26.

Instead, DPW said there are no existing guidelines for testing or reporting crypto in “finished” or treated water, and said the department is working with state and federal partners “to develop public notification guidelines based on this event and to ensure that the message of water safety is clearly communicated to the public.”

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Why was this testing required? What else is Baltimore doing?

Baltimore is required to test its open-air water reservoirs each month for parasites including crypto and giardia because the city is under a federal consent decree from the Environmental Protection Agency. In mid-May, the federal agency ordered Baltimore to finish work on two projects to protect drinking water by the end of the year.

The order detailed a list of project delays and requests for extensions from the city. At the time, city officials stressed their commitment to completing the projects by the end of the year, while objecting to the federal government’s decision to impose mandatory deadlines.

Under the federal order, Baltimore has a Nov. 30 deadline to get storage tanks at Ashburton operational, and a Dec. 30 deadline for tanks at Druid Lake. On its website, DPW says functional use is “scheduled” for the locations on their respective deadlines.

The federal consent degree, which the city has been under since 2010, states that Baltimore must bring its five uncovered drinking water reservoirs into compliance with the federal Safe Drinking Water Act; Druid Lake and Ashburton are the only two that are not yet in compliance.

The delayed projects “have been subject to unavoidable and extensive delays due to unforgiving site conditions, weather delays, supply and worker shortages caused by the COVID 19 pandemic, supply chain delays etc.,” DPW spokeswoman Jennifer Combs wrote in an email to The Banner.

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Why does testing take so long?

That’s a little complicated. A one-week turnaround time for crypto testing is standard in most cases. Testing is complicated, and it requires technical expertise to pull off.

But when there is confirmed, or even suspected, cryptosporidium in a water supply, many labs can offer expedited testing. DPW officials said Monday night that the lab it contracts with, Analytical Services, Inc., could not offer a quicker turnaround time.

“Please note that Cryptosporidium detection in finished water is uncommon and; therefore, there are no established state or federal guidelines. DPW continues to coordinate with our federal and state regulatory partners to establish notification guidelines as we collect more information,” Combs wrote in an email.

How dangerous is it?

The disease can lead to life-threatening complications (largely from dehydration) in those with weakened immune systems. If symptoms develop, they can last two weeks or longer. And, according to Johns Hopkins Medicine, the parasite can be passed in the stool of infected people, even those without symptoms, for up to two months.

The Centers for Disease Control and Prevention says most healthy people experiencing symptoms will recover from crypto without treatment, and recommends staying hydrated and eating a balanced diet to speed recovery. There is an approved prescription called nitazoxanide for diarrhea from cryptosporidiosis.

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Those at risk, according to the CDC, include patients with HIV/AIDS, some cancer patients and others who may have a suppressed immune system. Young children and pregnant people may be more likely to become dehydrated from diarrhea, according to the agency, so they should take precautions to remain hydrated.

What about pets?

Cryptosporidiosis is rare in healthy pets, much like it is rare in healthy people. Dogs affected by the parasite will often have diarrhea. Dogs and cats can carry the parasite in their stool without showing symptoms of infection, so it is always important to clean up after your pets and to wash your hands after handling pet waste.

If your pet is experiencing symptoms, you should contact your veterinarian as soon as possible.

Which areas are affected?

Because of how water infrastructure is handled in Baltimore and around the region, only parts of the city and surrounding areas are affected. Baltimore City officials published a map of the affected area, which stretches as far north as Sparks and Cockeysville in Baltimore County, through parts of Baltimore City, and into southwest Baltimore County and part of of Howard County.

When Baltimore officials published a map of the affected area, they initially included just a sliver of Howard. However, county officials published their own version of a map that shows an affected area there that’s significantly larger than the area designated by Baltimore officials.

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Why the discrepancy?

Howard officials said it’s because of how the county stores and distributes water once it’s received from the city and so, out of an abundance of caution, they’ve designated a larger impact area. On its website, the Howard County Bureau of Utilities said it is continuing to test the water.

What precautions are necessary?

Infection for most healthy people is a very small risk, and the affected area is not under a general boil-water advisory, unlike the E. coli outbreak last year. So, for most people, no action is necessary.

However, for those who are at risk, Baltimore officials suggest drinking bottled water, instead of tap water, and boiling tap water for one minute before consuming.

Over the weekend, DPW started delivering bottled water to senior centers, nursing homes, senior buildings and assisted living facilities with 20 or more residents within the affected area in Baltimore City.

Some, but not all, home water filters are able to remove cryptosporidium, according to the CDC. Filters that say “reverse osmosis” on the label protect from the parasite. Those that say “carbon filter” or “water purifier” may not protect from crypto.

Is it safe to consume restaurant ice?

“It’s really about where you’re eating,” said Rachel Rosenberg Goldstein, assistant professor with University of Maryland Institute for Applied Environmental Health. Goldstein said people eating at a restaurant in the impacted area should ask restaurant staff to make sure that the ice being used was made with uncontaminated (i.e., not locally sourced) water. Ice made with water from the impacted area still needs to be boiled or filtered, she said.

Is the water safe for washing dishes and rinsing veggies?

People should use the same precautions for water they use to prepare food as they do for water they drink, Goldstein said. She added this applies only to raw fruits or vegetables, as the process of cooking food would kill any lurking crypto.

But that means those who are at high risk for severe illness from a crypto infection should boil the water they use to wash dishes.

Should pregnant people take precautions?

Yes. Getting cryptosporidiosis while pregnant is more likely to cause dehydration, which can lead to more severe illness, Goldstein said. Diarrhea — the primary symptom of a crypto infection — is particularly dehydrating, she said, so pregnant women should aggressively hydrate with uncontaminated fluids if they’re experiencing gastrointestinal symptoms.

“It’s really about your own comfort with risk level,” Goldstein said, and for vulnerable groups it’s always better to err on the side of caution to reduce risk.

Is it safe to drink the water while breastfeeding? Should you boil water before using it in baby formula?

Cryptosporidium cannot pass through breast milk, Goldstein said. Infants and children who contract cryptosporidiosis are also at greater risk of becoming dehydrated, she said, so breastfeeding “can be really beneficial” for infants who are infected because it helps with hydration.

Kids and infants with GI symptoms should also up their fluid intake, she said.

Since infants and children are at greater risk for severe disease with a crypto infection, one way that parents can reduce risk is to take the same precautions recommended for other vulnerable populations, Goldstein said — giving them bottled water to drink, boiling water for a full minute and letting it cool, or using an approved filter.

Water should be boiled before adding to formula, Goldstein said.

‘Can I at least use the water in my bong?’

This one was a question from a reader. Maybe it was a joke, but we asked Goldstein anyway.

“This question in particular is outside of my area of expertise,” Goldstein said. “But I think the important thing to emphasize is that the greatest risk for crypto infection comes from ingesting contaminated water.”

This story may be updated.