Analies Dyjak, M.A. & Christina Liu, B.S. | Science Team   

Whenever we pour something down the drain or flush the toilet, it’s easy to think “out of sight out of mind.” However, the things we put down the drain can impact water quality in a big way. This article highlights exactly what not to pour or flush down the drain.

Where Does The “Stuff” That Goes Down The Drain Go?

All of the water flushed or washed down the drain goes through your city’s sewer system and into the wastewater treatment facility. The water that’s used to flush your toilet, take a shower, or wash your dishes all end up in the exact same spot. The wastewater treatment facility will treat the used water for a variety of pollutants. Once the water goes through the various processes, it’s released into local waterways to be recycled for a number of different purposes (including drinking water!).

Do Wastewater Treatment Plants Remove “Everything”?

It’s easy to assume that a wastewater treatment plant might remove absolutely everything from incoming wastewater. That isn’t entirely the case. Wastewater treatment plants do a really good job at removing larger solids, biological/bacterial contaminants, and sediment. They do not remove many chemicals, pharmaceuticals, hazardous materials, industrial waste, or pesticides. This puts a lot of pressure on drinking water treatment plants to carry a majority of the tap water purification. Some wastewater treatment plants are outdated and aren’t able to remove these types of pollutants, while others are not even required to do so. Click here for an in-depth video on how wastewater treatment plants actually work.

To help ease the burden on wastewater and drinking water treatment plants, here’s a list of things you should never pour or flush down the drain:

Pharmaceuticals: Old or unwanted prescription/over-the-counter medications should never be flushed down the toilet or sink. Water treatment plants are unable to remove most pharmaceuticals, which means that trace amounts end up in our tap water. Small amounts or levels below therapeutic doses are currently not a cause for concern but if people continue to dispose of medications down the drain, these levels of pharmaceuticals may accumulate. For guidance on how to properly dispose of pharmaceuticals, check out the FDA’s best practices for disposal of unused medicines.

Grease: Aside from the obvious reasons why you should never pour grease, oils, or fats down the drain, doing so can actually cause issues at a much larger scale. Whatever grease you pour down the drain congeals with everyone else's, and can form a mass in the sewer system. The mass can block other wastes from passing through, creating a major sewage blockage (like we saw in Detroit, MI). Check your city’s municipal utility company to see if they have a cooking oil collection program. If not, the best recommendation is to collect the used oil in a leakproof jar, seal it up, and throw it away in the trash.

Motor Oil: Never pour used motor oil or other automotive fluids (including antifreeze, solvents and gasoline) down a drain in your house or garage, into a storm drain, onto the soil, into a waterway, or in a manhole on a sidewalk. Used motor oil can contain toxic heavy metals such as zinc, lead, and cadmium that can contaminate drinking water. In fact, one quart of oil poured down a storm drain can contaminate one million gallons of water. One pint of oil can produce a slick of approximately one acre of water. When oil enters a body of water, a film develops on the surface that blocks out sunlight that plants and other organisms need to live. Please note that unlike cooking oil, you also cannot dispose of motor oil in the trash, and many cities will issue stiff fines for dumping toxic waste into landfills. Always bring used motor oil to local used oil collection centers. 

Paint: Whether it’s latex, acrylic, or oil, paints can clog your pipes and potentially leach toxic compounds into the water. If you can, first try to see if the leftover paint can be reused. School drama clubs or community theaters will often be happy to take unused paint! If the paint can’t be reused and must be disposed of, avoid throwing it away. Bring paint to local household hazardous waste collection locations/events. Don’t clean brushes in the sink, but use rinse buckets, and let the paint residue settle overnight from the old rinse water before pouring the water down the sink, leaving the congealed and dried paint at the bottom of the bucket, where it can be peeled or scraped off and thrown away.

Important Takeaways:

Wastewater treatment plants are primarily designed to treat the biological materials in the water, but are NOT equipped to treat the water for chemicals such as pharmaceuticals, cooking oil, household grease, motor oil and other automotive fluids, paint, photographic chemicals and others. A good rule of thumb is, when in doubt, don’t pour it down the sink or into sewer or storm drains. Check with your local authorities for toxic waste disposal locations.

Editor's Note: We've been writing more articles about organic chemicals like endocrine disruptors, methylated mercury, so we've been getting a lot of questions about how people become exposed to these chemicals. Even though these questions deal more with food than drinking water, we though that it'd be worthwhile to spend some time on an article explaining how this happens.

What is Bioaccumulation?

Bioaccumulation refers to the process of toxic chemicals building up inside of an organism’s body. This happens when a chemical is consumed or absorbed, and the body cannot catabolize or excrete it quickly enough. Mercury is a well-known chemical that will bioaccumulate in humans. We commonly hear about mercury exposure resulting from eating fish such as tuna (or other large predatory fish). However, mercury as well as many other harmful chemicals can also be found in drinking water supplies across the United States.

Chemicals that tend to bioaccumulate are stored in cells and not exposed to direct physical or biochemical degradation. These chemicals can collect and hide-out, particularly within adipose tissue (fat cells). Fatty mammary tissue often contains the highest concentrations of toxic chemicals. These chemicals in our mammary tissue are then passed along to infants when nursing.

What is Biomagnification?

Biomagnification refers to the process of toxic chemicals increasing in concentration as they move throughout a food chain. Bioaccumulation and biomagnification often work hand-in-hand; one animal accumulates chemicals in the body (bioaccumulation) and then a larger predator consumes that smaller animal such that the chemical is passed along to the predator. The chemical “magnifies” as the resulting concentrations increase in the predator because it likely consumes large quantities of that particular prey throughout its lifetime (biomagnification). As top-level predators in our own food chain, humans tend to collect high concentrations of toxic chemicals in our bodies.

What are Persistent Bioaccumulative Toxics (PBTs)?

PBTs are a particular group of chemicals that threaten the health of humans and the environment. Examples include methylmercury, polychlorinated biphenyls (PCBs), dichloro-diphenyl-trichloroethane (DDT), and dioxins. PBTs are considered extremely dangerous to both humans and wildlife because they remain in the environment for a very long time without breaking down, then bioaccumulate and biomagnify in ecosystems (including ours).

PBTs can also travel long distances and move between air, water, and land. DDT, a notorious environmental pollutant, was developed as a synthetic insecticide in the 1940s. Sprayed over crops, DDT would then wash into water supplies and contaminate lakes, ponds, streams, rivers, and oceans. Small organisms such as plankton and algae absorb DDT through the water. Smaller fish then consume the contaminated algae and plankton. Larger predatory fish then consume the smaller fish. Eventually, large predatory birds or humans eat the contaminated fish. Despite being banned in the United States over 40 years ago, DDT is still found in soil and water supplies today. In addition, humans contain the highest concentrations of DDT when compared to other organisms.

How Does This Impact Human Health?

Exposure to PBTs has been linked to a wide range of toxic effects in humans and wildlife. Some of those adverse effects include but are not limited to disruption of the nervous and endocrine systems, reproductive and developmental problems, immune system suppression, and cancer.

How Can I Minimize Exposure To PBTs?

1. Avoid eating species of fish that are long-lived and high on the food chain such as tuna, marlin, shark, swordfish, king mackerel, and tilefish.
2. Use a high quality water filter that removes PBTs (e.g. DDT, Dioxins, BPA, Phthalates) from contaminated drinking water before the chemicals get a chance to accumulate in you.

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Eric Roy, Ph.D.  |  Scientific Founder

This past week, the Environmental Working Group (EWG) released a website where people punch in their zip code, and view contaminants found in their water. As a company that uses water quality data to optimize each customer’s water filter, we applaud EWG for putting in the enormous amount of time & effort to build the database so the public can learn about their water. Unfortunately, we are seeing that these data are being used to generate inflammatory headlines, which can leave consumers confused and unnecessarily panicked.

We will be updating this water quality database blog post as more questions come in. If you have your own question, please reach out to us (hello@hydroviv.com). One of our water nerds will do their best to get back to you very quickly, even if it’s outside of our business hours.

Frequently Asked Questions 

Updated July 31, 2017

Are All Potential Contaminants Listed In The EWG Tap Water Database?

No. The EWG Tap Water Database pulls data from municipal measurements, but municipalities are only required to test for certain things. Simply put, you can’t detect what you don’t look for. One example of this can be seen by punching in Zip Code 28402 (Wilmington, North Carolina) into the EWG Tap Water Database. GenX, a chemical that has been discharged into the Cape Fear River by Chemours since PFOA since 2010, is not listed, even though it’s been in the center of a huge topic of conversation for the past 2 months in the local media.

Why Is The “Health Guideline” Different Than The “Legal Limit?”

The two different thresholds use different criteria. For example, the “Health Guideline” cited by EWG for carcinogens is defined by the California Office of Environmental Health Hazard Assessment (OEHHA) as a one-in-a-million lifetime risk of cancer, while the “Legal Limit” refers to the MCL which is the limit that triggers a violation by EPA. The OEHHA's criteria are established by toxicological techniques, while the EPA limits are negotiated through political channels. We wrote an article that addresses this topic in much more detail for those who are interested.

Why Am I Just Learning About This Now?

The EPA's Safe Drinking Water Act requires municipalities to make water quality test data public in Consumer Confidence Reports. These reports are required to talk about the water's source, information about any regulated contaminants found in the water, health effects of any regulated contaminant found above the regulated limit, and a few other things. As discussed before, the data in the EWG report use different criteria than the EPA, and it's hard for people to make sense of what's what.

Are The Data Correct If My Water Comes From A Private Well?

No. The EWG Tap Water Database only has data for municipal tap water. Private wells are completely unregulated, and there's no requirement to conduct testing. If you'd like us to dig into our additional water quality databases to help you understand likely contaminants in your private well, we're happy to do so. We don't offer testing services, but we're happy to help you find an accredited lab in your area, give advice on which tests to run, and help you interpret the results! We offer this service for free.

What About My City's Water Quality?

Hydroviv makes it our business to help you better understand your water. As always, feel free to take advantage of our “help no matter what” approach to technical support! Our water nerds will work to answer your questions, even if you have no intention of purchasing one of our water filters. Reach out by dropping us an email (hello@hydroviv.com) or through our live chat. You can also find us on Twitter or Facebook!

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