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« Back to Water quality

Where does water go once it flows down the sink drain? What about the water trickling down the street into storm drains? Or water discarded from industrial activities?

Wastewater is “used water” that’s created by households, cities, and industry. It’s most commonly associated with sewage, but we can also talk about surface runoff and stormwater that flows from roadways into storm drains. In any case, wastewater and stormwater eventually end up in the environment.

Because wastewater can come from many different sources, it can contain a variety of pollutants—soaps and personal care products, sanitary waste, pesticides and fertilizers, and fuel, to name a few. Industrial processes might produce wastewater laced with heavy metals or heated so hot that it harms living things nearby.

On this page we’ll collect and organize resources on wastewater and how people can begin to investigate it. Visit the wastewater tag page to see the latest community posts about wastewater on Public Lab, and get updates on this topic by following:

Follow wastewater

Sources: Wastewater pollution

Lead image: @alejobonifacio sampling along the Suquía River near a wastewater treatment plant.

On this page you can:

See community stories and projects on wastewater

Join the conversation
  • Ask a question, answer a question, or follow future questions on wastewater
  • Post an issue brief that describes your local concern about wastewater
Research wastewater

Learn about regulations for wastewater and what community members can do

Find further reading and resources on wastewater

See next step challenges in wastewater community science and method development

Community stories and projects

Public Lab community projects tagged with wastewater-project will appear here

Title Updated Version Views Likes
GLAM over 9 years ago by liz 7 688 5

You can also find stormwater-related projects here:

Join the conversation

Questions from the community

  • See if other community members are asking questions like yours
  • Ask a question so other community members can offer support
  • Sign up below to be notified when someone asks a wastewater-related question

Questions tagged with question:wastewater will appear here

Post an Issue Brief

Share a local concern or issue about wastewater pollution and get support from the Public Lab community by writing and posting an Issue Brief. Visit “Write an Issue Brief” to find information on what an issue brief is, see examples, and learn how to write one.

Research wastewater

investigating pollution

Image: @warren

The Public Lab community is here to support people as they plan and carry out investigations into local wastewater pollution. Anyone can ask questions, start an issue brief with any amount of information available, or start documenting a project.

Some places to start

Here are some activities you might want to try when starting to research wastewater pollution.

Information on wastewater pollution

Sewer systems and how people get exposed to wastewater

In cities and towns in the US, you’ll mostly find two different kinds of sewer systems that collect and transport wastewater: combined sewer systems and separate sewer systems.

Combined sewer systems collect both stormwater runoff from storm drains AND raw sewage from buildings and households. The stormwater and sanitary sewage are both directed in a single pipe to a wastewater treatment plant to be cleaned. When there are heavy rains, however, this increases the amount of stormwater flowing into the combined system. Not all the extra incoming water can be handled by the wastewater treatment plant, and so the rest is released directly into the environment as a Combined Sewer Overflow (CSO), raw sewage and all.

In New York City, for example, about 60% of the city is served by a combined sewer system.

Separate sewer systems have, as one might guess, separate pipes for stormwater and sanitary sewage. Many stormwater systems in the US are Municipal Separate Storm Sewer Systems (MS4) that have to follow regional and federal permit regulations to reduce water pollution. In most cases, though, the stormwater isn’t fully treated before it gets released into the environment.

A separate sanitary sewer system transports raw sewage from households, businesses, and other buildings to a wastewater treatment plant. There, the sewage is treated and the cleaned water is released into the environment.

combined sewer separate sewer

With any kind of sewer system, there’s the threat of exposing people to wastewater. Untreated or under-treated wastewater can make its way into waterbodies that people use for recreation, fishing, or drinking water. Pollutants can also become airborne when wastewater enters coastal areas. The wastewater might be legally released under a permit, it might be illegally dumped, or it might leak from broken pipes and other sewer system infrastructure.

Wastewater pollutants

Methods to monitor wastewater

Detecting possible wastewater pollution

Lots of information (in English and Spanish) about what to look for in the comments of this question: What are some observable tell-tale signs of wastewater pollution?

Check out the wiki page below on different methods for detecting wastewater pollution:

On that page, you’ll find information on monitoring some water quality characteristics that could indicate wastewater pollution:

  • Water color or clarity
  • Odor
  • Water temperature
  • Conductivity
  • Indicator chemicals or components


Activities on Public Lab that have been tagged with activity:wastewater will appear here

Purpose Category Status Author Time Difficulty Replications
¿Cómo evaluar la calidad de un río con insectos acuáticos (bioindicadores)? / How do I assess the quality of an river with aquatic insects (bioindicators)? - - @alejobonifacio - - 0 replications: Try it »
¿Cómo detectar abrillantadores ópticos (aguas residuales) yendo a un río? / How to detect optical brighteners (wastewater) going to a river? - - @alejobonifacio - - 0 replications: Try it »
¿“Pelo” gris en el agua ríos y arroyos? - - @alejobonifacio - - 0 replications: Try it »
How to find out if waterbodies near you in the US are healthy or impaired observe - @bhamster 30m easy 0 replications: Try it »
Did you see gray “hair” in the bottom of freshwater bodies? - - @alejobonifacio - - 0 replications: Try it »
How to report pollution entering your local stormwater system in the US - - @bhamster - - 0 replications: Try it »

Activities should include a materials list, costs and a step-by-step guide to construction with photos. Learn what makes a good activity here.

Regulations, policy, and advocacy

US federal regulations

State and local regulations

International regulations

Please share more here!


In general, how can community members take action on wastewater pollution?

Further reading and resources


Wiki pages related to wastewater

Title Updated Version Views Likes
Wastewater almost 3 years ago by bhamster 2 264 0
Detecting wastewater pollution almost 3 years ago by bhamster 3 463 2
NPDES over 7 years ago by warren 17 953 0

Next step challenges

  • Collectively create a “hotsheet” of local/regional stormwater pollution reporting numbers
  • Spectrometry methods for wastewater:
    • Determining spectral signatures of wastewater pollution so different forms of contamination can be detected in real time with a DIY spectrometer
    • There are some developments on spectrometry methods linked here on the detecting wastewater pollution wiki
  • Modifying spectrometers:
    • Modifying a DIY spectrometer into a fluorometer for detecting optical brighteners in stormwater outfalls (possibly as a follow up to this activity?)
    • Modifying a DIY spectrometer into a luminometer for measuring light output from bio- or chemiluminescence assays of sampled water.
  • Bioindicators and biological tests of wastewater:
  • Methods that help enable recycling of biosolids that result from wastewater treatment:
    • At wastewater treatment facilities, identifying and isolating harmful chemicals that won’t break down and would otherwise end up back in the environment from biosolids recycling. For example, PFASs (per- and polyfluoroalkyl substances), commonly used to make surfaces nonstick or water repellent. (Idea from @jesseslone)