Where Does Tap Water Come From And Is It Safe to Drink?

what is tap water

Let’s talk about tap water. Many of us in the United States have easy access to tap water at home and in restaurants. But what exactly is in our tap water? Where does it come from and is it safe to drink? In this article, we explore everything you need to know about tap water, one of the most overlooked staples in your diet.

Where does tap water come from?

Tap water in the United States comes primarily from three sources — lakes, rivers, and groundwater. The source of your tap water depends entirely on where you are located. With over 100,000 lakes and 250,000 rivers across the US, plus hundreds of reservoirs, there’s a lot of variance in water sources for Americans. Some cities, like Boston and San Francisco, get 100% of their drinking water from reservoirs, while other cities rely on rivers and lakes, or a combination of both. For example:

  • Washington DC collects 100% of its drinking water from the Potomac River
  • New Orleans collects from the Mississippi River
  • Chicago relies on Lake Michigan
  • Half of Los Angeles’ water comes from the Owens River
  • 90% of New York City’s water comes from the Catskill/Delaware Aqueduct

Though it is rare, some water is supplied from newer sources like seawater in San Diego County. While the majority of the world’s water exists in the oceans, very few cities are converting saltwater into drinking water. Desalination (the process of converting seawater to drinking water) is cost prohibitive and the lack of technology makes it a challenging investment for most cities. The cost per gallon from a desalination plant can cost consumers up to 2.5x more per month.

How is tap water treated?

From the source, your water is sent to a treatment facility to be processed and sanitized before it is directed to your faucet. There are four steps in the treatment process: coagulation and flocculation, sedimentation, filtration, and disinfection.

The first step, coagulation and flocculation is a process in which chemicals are added to the water to clump small particles together. This process helps form larger particles that can be easily filtered out. The common reagents added during this process include aluminum salts, polymers, iron, activated carbons, talcum, and activated silica. When they bind together, this is called “floc.” The sedimentation process occurs next when the floc settles at the bottom of the tank. Once the floc has settled, water is then filtered to remove any fine particles of dust, parasites, microorganisms, bacteria, and chemicals.  Finally, the water is disinfected to ensure any remaining microbial contaminants are destroyed. To do so, chemicals such as chlorine, chlorinates, or chlorine dioxides are added to the water. Disinfecting the water with these chemicals is a quick way to prevent outbreaks of waterborne infections and parasitic diseases, according to the World Health Organization (WHO). This is also the stage where some cities add fluoride to prevent tooth decay — don’t worry, we’ll dive into that further.

What's In Tap Water and is it safe?

Tap water is relatively safe. However, some of the most common contaminants that remain in our tap water after treatment include aluminum, arsenic, copper, iron, lead, pesticides, herbicides, uranium, and more (Neilsen Research Corporation). Each of these contaminants poses dangerous side effects. For example, consumption of too much copper can lead to liver damage and kidney disease. Lead, on the other hand, generally comes from the pipes that the water travels through, and it can have life-altering effects on developing children (slowed growth, anemia, lower IQ, and more), pregnant woman (causing premature birth and reduced growth of the fetus), and adults (reproductive problems, decreased kidney function, and cardiovascular effects). Several cities are plagued with lead-infested water, including the now widely-known case of Flint, Michigan where city officials outright neglected the health crisis. Other cities have also had challenges with lead in their water supply infrastructure, including Pittsburg, Pennsylvania, and Milwaukee, Wisconsin. Some of the most contaminated water can be found in low-income rural areas, according to the New York Times, including areas of Oklahoma and Texas.

Pharmaceuticals have also been found in water supplies that enter through the sewage system — through either human excrement (in the toilet) or when people flush their medication down the toilet. The WHO warns that we do not know the long-term effects of drinking trace amounts of pharmaceuticals – it is certainly not something we should consume daily. The chlorination treatment process that most tap water undergoes removes only about 50% of the pharmaceuticals from public water systems, according to WHO, but it depends on the type of drug, according to a study by Harvard.

It’s not just foreign contaminants that prove to be an issue in our tap water — it’s also byproducts of the treatment process itself. Introducing chlorine into our water system produces halogenated disinfection byproducts (DPS), which has shown a link to bladder cancer as well as reproductive and developmental effects. Every city has a water supply with a unique combination of contaminants, and you can check your local report using the EWC’s Tap Water Database by entering your zip code. You may also refer to the EPA’s comprehensive list of regulations for known contaminants and their acceptable levels.

Ultimately, tap water is regulated by the EPA who sets limits on 90+ contaminants in our water supply through the federal Safe Drinking Water Act (SDWA), though the policy only applies to public water systems that serve more than 10,000 people. Communities smaller than 10,000 are not regulated under the SDWA — instead, they are monitored every five years for only 30 contaminants through the UCMR (Unregulated Contaminant Monitoring Rule) by the EPA.

is tap water safe

Why is fluoride in tap water? Is it good for my teeth?

Fluoride has been added to the majority of the US public water system since the 1960s, but not without controversy. Historically, fluoride has been added to our water to aid in the prevention of cavities, and there has been much debate about the health risks associated with ingesting this gas (yep - fluoride is a gas). As of 2014, about 74% of people with community water systems (public water) received fluoridation, varying by state (Hawaii has the lowest rate at 11.7% while Washington DC has 100% fluoridation rates), according to the Center for Disease Control (CDC). Ironically, the overall rate of cavities across the globe is decreasing for all populations regardless of fluoride treatment, Harvard reports. We can probably attribute toothpaste, electronic toothbrushes, as well as increased education on dental hygiene for this overall decrease in cavities.

Unfortunately, fluoride doesn’t simply levitate on your teeth, research shows a number of various concerns about the ingestion of fluoride and how it affects cognition. A 2014 research study found that fluoride poses “significant costs in relation to cognitive impairment, hypothyroidism, dental and skeletal fluorosis, enzyme and electrolyte derangement, and uterine cancer.” It has not been proven that ingesting fluoride via your tap water is the best way to prevent cavities — most dental hygiene products that contain Fluoride are equally, if not more effective.

Is there anything beneficial in my tap water?

Despite the fact that you can buy “mineral water” in bottled form, there are usually trace amounts of naturally occurring minerals in your tap water as well. These include calcium, magnesium, and sodium which were all found in levels that are high enough to support healthy intake. Those minerals are sometimes stripped, however, according to a research study out of Washington University in St. Louis and vary from city to city.

What are the alternatives to tap water?

Despite common misconception, bottled water doesn’t prove to be a safer or cleaner alternative to tap water. In addition to the energy usage and the abundance of plastic waste it creates on our planet, bottled water hasn't been shown to be safer for human consumption or lower in contaminants. And while tap water is regulated by the EPA, bottled water is regulated by the FDA which has an entirely different set of guidelines that are more focused on labeling (they do have some regulations, but not as substantial as the EPA). A 2014 study also showed that BPA and PET will leach into plastic water bottles if they are left in warm conditions (borosilicate glass bottles are a much safer alternative to store water and will not leach contaminants). And as you’ve probably heard, plastic bottled water is often just tap water that has been repackaged from your local municipal line and resold to you. In many cases, they are selling you something (bottled tap water) that you can generally access yourself, for free.

Another option to consider is spring water. Spring water (sometimes called raw water or live water) comes directly from natural springs without excessive treatment or filtering. Natural springs are large aquifers (deep underground lakes), that are far removed from human waste and surface contamination. Compared to tap water, spring water avoids fluoridation and chlorination. Another benefit of spring water is that it does not travel through hundreds of miles of age-old pipes since it is bottled at the source. Natural spring water hosts a number of potential health benefits including a higher mineral count than tap water; It’s’s alkaline and helps balance the acidity in your body, and provides live probiotics derived from the (good) bacteria found in spring water. If you would like to try spring water, it’s suggested to do so through a professional delivery service which conducts third-party testing on its water supply. Spring water is a naturally occurring mineral-rich source of water and it is how humans have been consuming water for millennia – but as with all forms of untreated water, the source must be verified to ensure the water has not been running above ground, risking the intrusion of pesticides or contamination.

It’s clear that we have several variables to consider before committing to a specific water source for our daily hydration needs. Clean, mineral-rich water is integral to mind and body wellness, as well as households with developing children. Without a doubt, drinking tap water exposes you to chemicals and contaminants. It is only regulated for relative safety markers, and for some families, it is simply the most affordable option. Some households may choose to purchase a water filtration system to remove the remaining contaminants in tap water. For example, reverse osmosis is a very strong filtration process that many people use, however, it is so powerful that it removes virtually all of the minerals (both good and bad). If you’re traveling abroad to a location that does not have safe drinking water, bottled water may be the safest option, or you can bring a water bottle that filters local tap. Spring water is the most “true to the source” option, maintaining natural minerals from the spring, but also comes with some risk if the water is not sourced properly – there are trusted spring water delivery services that can be easily found with a quick Google Search.

Clean water remains a fundamental requirement for proper cellular and vital organ function. In the end, only you can decide which option is best for you and your family, and which risks and benefits are aligned with your health goals.


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