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The presence of contaminants in water can cause a variety of health issues, ranging from gastrointestinal distress to cancer. A good quality water filtration system can prevent it. The quality of the water depends on various factors: the filtration process, the location of the water source and its quality, and the state of our pipes. Some populations are more sensitive to these contaminants: infants, older adults, pregnant women, and people with immunity problems, and should be more cautious with the quality of the water they ingest/bathe or shower in.

Here, we’ll explore different types of contaminants to watch out for, how to learn about the water quality in our location, the importance of having a regular inspection of the pipes in your house, how to choose a water filtration system, and some ways to decrease our exposure to THMs.

Common contaminants that can be found in our tap water

Some contaminants present in water have been shown to be endocrine disruptors, meaning that they can interfere with the body’s hormones, causing adverse health and reproductive outcomes. Here are some of those contaminants we should watch out for (1, 2):

• Disinfection byproducts

  • Disinfection byproducts (DBPs) are formed when disinfection agents such as chlorine come into contact with inorganic or inorganic matter such as leaves or vegetation in the source water.
  • The most common types of DBPs are trihalomethanes (THMs or TTHMs) and haloacetic acids (HAAs).
  • These DBPs can be absorbed through the skin and inhalation. Indeed, THMs (not HAAs) can be absorbed when we take a shower or a bath, or when going to the swimming pool.
  • Several factors can increase the formation rate of DBPs. In particular, increasing temperatures elevate the formation rates, such as when we boil water for cooking. In addition, water with low pH has been associated with high levels of DBPs. Generally speaking, demineralized water has a lower pH and contains low levels of magnesium and calcium. It is deemed as ‘soft water’. That’s because the minerals in hard water (mineralized) reduce the amount of acid in the water, resulting in a lower pH.
  • DBP concentrations are higher in pools and spas, probably due to the constant availability of disinfectants and organic matter from swimmers, and the trapping of the DBPs in the pool.
  • Epidemiological studies have shown an association between DBP exposure and an increased risk of cancer development and adverse reproductive outcomes.

• Fluorinated substances

  • Fluorinated substances: perfluoroalkyl and polyfluoroalkyl substances (PFAS) are present in a variety of consumer products: some food packages, waxes, paints, cleaning products etc., and are frequently found in the environment as well. In consequence, PFAS can be found in drinking water.
  • They have been associated with increased tumors, endocrine disruption, impaired neurodevelopment, and adverse reproductive outcomes.

• Bisphenol A (BPA)

  • BPA is a chemical used in polycarbonates plastics (which can be found in food and drink packaging) and in epoxy resins (which are used to coat metal products such as food cans and bottle tops).
  • Studies have shown that BPA can cause adverse health effects at low and environmentally relevant doses.

• Phthalates

  • Phthalates are a group of chemicals used in plastic to make it more flexible and durable. They are also used in solvents in personal care products such as shampoos, lotions, and cosmetics.

• Pesticides

  • Pesticides are added to water to combat disease-causing organisms. They can also enter the water through the overflow from agricultural fields.
  • The Netherlands National Institute of Public Health and Environmental Protection concluded that ‘groundwater is threatened by pesticides in all European states’. In addition, in the US, the United States Geological Survey (USGS) estimates that 1 billion pounds of pesticides are applied annually to agricultural land, non-crop land, and urban areas in the United States (3).
  • Atrazine is the most common surface and groundwater herbicide contaminant worldwide. Simazine is the second most commonly detected triazene herbicide in surface and groundwater and is commonly used in urban areas.

• Estrogens

  • Natural and synthetic estrogens are contaminants in the environment. The most frequent estrogens found in the environment are estrone, 17β-estradiol, 17α-estradiol, and estriol.
  • Estrogens are naturally produced by animals such as cattle, humans, and plants present in sewage.

• Volatile organic compounds (VOC)

  • Volatile Organic Compounds (VOCs) are chemicals that have a high vapor pressure at room temperature and can easily evaporate into the air.
  • Trichloromethane and MTBE (methyl tert-butyl ether) were the most commonly detected VOCs.

• Fluorides

  • While being considered contaminants, fluorides can be beneficial in preventing tooth decay when present in small quantities. Some water treatment devices that remove chemicals, such as reverse osmosis, ion exchange, or distillation systems, might also remove fluoride. Children who drink water with levels of fluoride <0.6 ppm might need a fluoride supplement.

Pipes

Pipes can also be a source of contaminants in water. It’s generally recommended to have your pipes inspected by a licensed plumber at least once every few years, depending on the age of your home and the condition of the pipes.

During a plumbing inspection, a plumber will examine your pipes for signs of wear and tear, corrosion, leaks, and other issues that can affect water quality.

Choosing a water filtration system

Step 1. Find out about the water quality in your area

When looking at the water quality in your area, keep in mind that assessing exposure and the health consequences of chemicals in drinking water can be challenging. Exposures are typically at low concentrations, in some locations measurements in water are sometimes not frequent enough, exposure periods are usually long, and multiple exposure routes may be involved (inhalation, ingestion, dermal absorption). Also, not all contaminants are tracked: for instance, pharmaceuticals, and little is known about their potential long-term effects at environmental concentrations on humans (4). Finally, it should be noted to note that while the country’s recommendations provide a benchmark for safe contaminant levels in drinking water, exposure to any level of a contaminant over a long period of time may increase the risk of certain health effects.

However, looking at the water quality in your location can be a good indication of quality levels. You can find this out by doing an online search with your location. You’ll know which contaminants are present above the maximum tolerable limits and which should be filtered out. Even if all contaminants are well below the maximum limits, you might still want to filter your water, for instance, if the samples taken are scarce, to improve the taste of the water, or simply if you want to minimize your exposure to contaminants.

If you get your water from a private well, you should have your water tested by a certified lab at least once a year.

Step 2. Do you need a whole-house filter system?

Water filtration tanks or whole-house filter systems: To protect yourself from VOCs, it is best to use a point-of-entry filter system (where your water pipe enters your house), because you can be exposed to VOCs during bathing and cleaning, as well as while cooking. Indeed, exposure from a 10-minute shower or 30-minute bath is about the same as drinking two and a half liters of tap water. Thus, if you notice that the VOC levels in your tap water are elevated, it could be worth purchasing a whole-house filtration system. However, you also have to take into account that whole-house filter systems are more expensive and quite clunky.

Step 3. Choose the type of filtration system.

• The function and type of the filtration system: Determining which type is most appropriate for you—or whether you need a filter at all—depends on what functions you want a filter to provide.  For instance, the sole function of some filters is simply to improve the taste of the water, and do not provide any protection from contaminants. Others reduce the ‘hardness’ of the water, by reducing the magnesium and calcium content of the water.
• There are different types of water filtration systems:

  • Filtration through pores

    • Microfiltration
    • Ultrafiltration
    • Nanofiltration

  • Reverse osmosis
  • Distillation systems
  • Ultraviolet treatment systems
  • Water softeners (for aesthetic purposes)

• Here’s a summary of the characteristics by the CDC of these different filtration systems worth looking at: https://www.cdc.gov/healthywater/pdf/drinking/Household_Water_Treatment.pdf
• Reverse osmosis systems are generally considered the most effective at removing a wide range of contaminants, followed by distillation systems. However, remember that no filter eliminates all contaminants, so understanding what filters do and do not do is important.

Step 3. Optional – Pick a filtration system that leaves the minerals in the filtered water.

Minerals, when present in water, can provide various health benefits, such as maintaining electrolyte balance, and supporting bone health. Some commonly found minerals in drinking water include calcium, magnesium, and potassium (5). While calcium and magnesium can be obtained through diet, drinking mineralized water can be helpful in reaching desired levels of minerals. When choosing a filtration system, you can verify whether the filtration system keeps the minerals in the filtered water. Some filtration systems remove minerals, in particular: reverse osmosis systems use a semi-permeable membrane to remove minerals, salts, and other contaminants from water. Also, distillation systems boil water to create steam, which is then condensed to produce purified water. The distillation process separates water from dissolved minerals and other impurities, resulting in mineral-free water. If the minerals are removed, another option would be to add mineral supplements to their drinking water or use a remineralization system to restore the minerals back into the water.

Step 4. Check for the NSF certification.

NSF certification: NSF International is an independent organization that develops public health standards for products.  One way to figure out what a water filter does is to look for an NSF certification on the label. You can look up specific products in the NSF database online to see what they are certified to protect against. Some of the NSF standards applicable to water treatments are standard 41 (taste and odor), 53 (cyst reduction), 58 (reverse osmosis), and 62 (distillation).

If you choose not to pick a filter with the NSF certification, it’s suggested to read the labels carefully and verify the manufacturer’s claims with an independent source.

What are other ways to reduce your exposure to THMs?

Since THMs are volatile, you can store drinking water overnight in an open container in the fridge and the THMs will evaporate. This is the 0-cost method of filtration, but it can leave many contaminants in the water.

You can also reduce your THM exposure by taking shorter showers/baths and by using a fan to make sure it is well-ventilated.

Conclusion

When choosing a filtration system, you need to take into account multiple factors: the quality of your water, the type of filtration system, the size of the filtration system, and whether the filtration system leaves out minerals in the filtered water. Also, to make sure that it does its job, make sure the filter is NSF certified.

References

1. Gonsioroski A, Mourikes VE, Flaws JA. Endocrine Disruptors in Water and Their Effects on the Reproductive System. International Journal of Molecular Sciences. 2020; 21(6):1929. https://doi.org/10.3390/ijms21061929
2. Centers for Disease Control and Prevention. (2022, July 18). Disinfection by-products (dbps) factsheet. Centers for Disease Control and Prevention. Retrieved March 30, 2023, from https://www.cdc.gov/biomonitoring/THM-DBP_FactSheet.html
3. Bexfield, L. M., Belitz, K., Fram, M. S., & Lindsey, B. D. (2022). Volatile organic compounds in groundwater used for public supply across the United States: Occurrence, explanatory factors, and human-health context. Science of The Total Environment, 827, 154313. https://doi.org/10.1016/j.scitotenv.2022.154313
4. Patel, M., Kumar, R., Kishor, K., Mlsna, T., Pittman, C. U., & Mohan, D. (2019). Pharmaceuticals of emerging concern in aquatic systems: Chemistry, occurrence, effects, and removal methods. Chemical Reviews, 119(6), 3510–3673. https://doi.org/10.1021/acs.chemrev.8b00299
5. Albertini, M. C., Dacha, M., Teodori, L., & Conti, M. E. (2007). Drinking mineral waters: Biochemical effects and health implications the state-of-the-art. International Journal of Environment and Health, 1(1), 153. https://doi.org/10.1504/ijenvh.2007.012230