Should Immunocompromised Patients With Cancer Worry About Drinking Water?

Nothing is more refreshing than a tall, cold glass of water. As we are regularly reminded to stay hydrated, most people don’t think twice before reaching for the faucet or a bottle of water.

But just how clean is that water? Is it safe for people to consume, especially those who are immunocompromised from cancer or its treatments?

While tap water from public systems is required to meet both federal and state standards, private systems such as wells, which are used by more than 15 million U.S. households, are not.

Ultimately, water from either source could contain contaminants, and, as a result, experts suggest that people with cancer test their water and, if problems are found, filter it.

Public Versus Private Water

The U.S. Environmental Protection Agency (EPA) regulates more than 90 contaminants in public water systems. Of these, possible carcinogens include byproducts that form when disinfectants like chlorine are added to drinking water and react with naturally occurring organic matter; organic and inorganic compounds including copper, lead, arsenic and cyanide; radionuclides that result from the erosion of natural deposits of radioactive minerals; and bacterial or parasitic threats such as fecal coliform and Giardia.

The maximum contamination level allowed by the EPA is based on the lowest concentrations of these substances that can be measured using current technology, the capabilities of water treatment facilities and the costs of cleaning water. However, when it comes to chemicals that are known to be carcinogenic and for which there is no safe dose, the standards are even stricter, with allowable levels of zero.

American household drinking water can have one of two origins: It can come from the surface of the land or under the ground. Either type can be treated to become safe drinking water, but the EPA notes that surface water may start out more polluted. Regardless of which is used in households, tap water quality can vary across the country. A recent example of this occurred in Flint, Michigan, where river water was corroding old pipes, which leached lead into the public water system; ultimately, lead was detected at high levels in the blood of people who lived in the area. This resulted in a state of emergency last December.

There is no guarantee that private well water is better than tap water, says Janet Stout, president and director of the Special Pathogens Laboratory and research associate professor at the University of Pittsburgh Swanson School of Engineering. A big concern with private wells is that they can become contaminated from runoff that contains pesticides or nitrates.

A recent study on private wells in northern New England shed some light on this. Researchers explained that residents of Maine, New Hampshire and Vermont have seen an elevated prevalence of bladder cancer over the past 50 years. The scientists found low to moderate levels of arsenic in the private well water there during their research. The study’s authors state that those who drank the most water from private wells had almost twice the risk of bladder cancer than those who drank the least.

The most recent numbers from the Centers for Disease Control and Prevention (CDC) on drinking water-related disease outbreaks found 32 such occurrences in 2011-2012 that caused 431 cases of illness, 102 hospitalizations and 14 deaths. Legionella was tied to 66 percent of the outbreaks yet caused only 26 percent of the illnesses, while viruses and non-Legionella bacteria were blamed for 16 percent of the outbreaks and caused 53 percent of the illnesses. Legionella in plumbing systems and untreated groundwater were the most common reasons for water-related outbreaks in those years, the CDC reports.

Turning to the Bottle

Last year, Americans used 50 billion plastic water bottles. But is this water better than what comes out of a tap? Nagi Kumar, director of cancer chemoprevention at Moffitt Cancer Center in Tampa, Florida, feels it is, and recommends that her patients drink bottled water from a reputable source. Her advice is to look for the words “reverse osmosis” on the label, which indicate that the water was cleaned in a specific way.

Confirming that the water was filtered, and how, could be especially important, since, according to Aaron Barchowsky — professor of environmental and occupational health at the University of Pittsburgh Graduate School of Public Health — approximately 50 percent of bottled water comes from municipal water sources. In a 2011 survey of more than 170 bottled waters, the Environmental Working Group (EWG) found that only three brands listed facts on their labels about where the water came from, how it was purified and what chemical pollutants remained after the water had been treated.

Furthermore, there has been concern about the health risks associated with bisphenol A (BPA) and phthalates, which are in some plastics. BPA tends to be used in hard-plastic, reusable drink bottles, but not the soft, prefilled, one-time-use water bottles typically purchased at drug, grocery or convenience stores. Those softer bottles, however, may contain phthalates. Both chemicals are thought to be linked to hormonal disruption, especially in young people, but neither substance has been definitively linked to cancer risk in humans.

Taking Action

If you feel concerned about your tap water, there are precautions you can take. The first step is to have your water tested. Local water authorities will often test tap water free of charge. If that is not an option, you can find a state-certified lab through the EPA at http://tinyurl.com/hon55e5 or by calling the agency at 1-800-426-4791.

If you’ve had your water tested and found that it contains contaminants beyond the levels the EPA allows, it’s a good idea to filter your water, Barchowsky says. But if testing has not detected an inappropriate level of contaminants, he suggests, filtering would be an unnecessary expense, even for patients with cancer.

If you plan to get a water filter for your household, make sure it fits your needs regarding budget and what contaminants it will remove.

Stout recommends a point-of-use filter with .2 microns or smaller pores, or holes, to filter out bacteria, saying “it provides an extra layer of protection.”

Meanwhile, a filter using activated charcoal can remove contaminants like chlorine, lead and trihalomethanes. For those on a tight budget who want a charcoal-based device, the EWG suggests a carafe filter or faucet-mounted filter. A more comprehensive option, particularly for the removal of chemicals, is a reverse osmosis filtration system combined with activated charcoal. This technology filters out everything caught by the charcoal and reduces other contaminants including arsenic, nitrates, hexavalent chromium and perchlorate. Barchowsky suggests using a compound water cleaner that employs a variety of technologies, such as carbon or charcoal filters in addition to purification systems that use ozone or ultraviolet light, to destroy both bacteria and carcinogens.

Consumer Reports notes that prices range from $20 for a carafe water filter to $1,800 for a reverse osmosis filter. And having a filter also requires extra work. The EWG says that some systems require maintenance, such as replacing the filter periodically to avoid bacteria from forming a biofilm, which could defeat the purpose of a person using a water filter to begin with.

“If you are talking about a (carbon faucet or pitcher) filter, then, yes, any bacteria in the water (assuming there are appreciable bacteria) may start to accumulate in the filter and form a biofilm,” says Barchowsky. “Brita says up front that their filters are not designed to filter out bacteria. But they have recommendations for replacement frequency so that there is little risk of the bacterial growth being a problem.”

Some makers of water filters ask third-party organizations to test their products and certify that they do what they are designed to, and are safe to use. In fact, through these organizations, some filters may receive certification under NSF/ANSI Standard 42 stating that they are “bacteriostatic,” meaning they will not add bacteria to water. Buyers can check their filters for safety certifications from NSF, CSA, UL or WQA, but the best way to avoid concern about bacteria buildup, experts say, is simply to change your filter on time.

Overall, experts advise that immunocompromised individuals talk with their physicians about whether they should drink their water the way it comes out of the tap, or apply a filtration or purification system first.