Wastewater Treatment and Recycling

From Beachapedia

By Caroline Gleason
Last Updated: 8/4/21

Introduction to Wastewater Treatment and Recycling

The majority of sewage infrastructure in the United States consists of centralized wastewater systems, in which sewage and wastewater from homes, businesses, medical facilities and more is discharged to a network of sewers, and transported to a central wastewater plant for varying levels of treatment. This is in contrast to decentralized wastewater systems, like septic systems and cesspools, which serve individual homes or small communities.

The nation’s wastewater infrastructure has been neglected in recent years, receiving a D+ from the American Society of Civil Engineers in their 2021 infrastructure report card. [1] This neglect has led to a worsening problem of sewage pollution in our ocean and waterways. An understanding of the basic concepts of stormwater and wastewater collection and treatment is necessary to help Surfrider activists and other concerned citizens address water pollution problems that result in beach closures, adverse human health effects, and a stressed aquatic environment.

The first important concept to understand is that in most locations, there are two separate sewer systems -­ a stormwater sewer system and a sanitary sewer collection and treatment system. These systems have distinctly different purposes, and are described in depth in our Sewer Systems Beachapedia article. This article will focus on where that wastewater ends up: a wastewater treatment plant. But first, a quick primer on sewer systems.

Types of Sewer Systems

Stormwater sewers are gravity-driven systems designed to prevent flooding problems from rainwater runoff. [2] Civil engineers design these systems to be water superhighways. The goal is to get rainwater and other urban runoff away from residential, commercial, and industrial areas as fast as possible to prevent flooding, and discharge it to a creek, river, or directly into the ocean. Read more about stormwater infrastructure in our Sewer Systems Beachapedia article.

Sewage collection and treatment systems, also sometimes referred to as sanitary sewer systems, collect and treat wastewater flowing from appliance drains (toilets, sinks, showers, washing machines, and dishwashers) inside buildings, such as residences, businesses and medical facilities, collectively referred to here as “households”. In a centralized system, wastewater travels from households to treatment plants through a series of pipes called sewer lines. Like stormwater systems, sewer systems typically make maximum use of gravity to convey wastewater to a treatment facility. Because of this concept of gravity flow, treatment plants are frequently located in low areas next to rivers or the ocean. If wastewater does need to be pumped, the water flows into a concrete pit in the ground called a lift station or pump station, where pumps are used to transfer it through a force main (pressurized sewer) to the treatment plant. [3] As mentioned above, this article will focus on what happens to wastewater when it arrives at the central treatment plant; to learn more about sanitary sewer systems and the issues associated with them, check out our Sewer Systems Beachapedia article.

Lastly, approximately 772 municipalities across the US use a third type of sewer system for their wastewater management, called a Combined Sewer System. [4] Combined sewer systems (CSSs) are sewers that are designed to collect rainwater runoff, domestic sewage, and industrial wastewater all in the same pipe for transport to a wastewater treatment plant. In dry weather or during periods of light rain, CSSs are able to handle both stormwater and wastewater input and treat it before discharging back into the environment. During periods of heavy rainfall or snowmelt, however, the wastewater volume in a combined sewer system often exceeds the capacity of the sewer system or treatment plant. When this happens, combined sewer systems are designed to overflow, discharging excess (untreated) wastewater directly to nearby streams, rivers, or other water bodies in events called combined sewer overflows (CSOs). Across the United States, CSOs release around 850 billion gallons of diluted yet untreated sewage into surface waterways every year. [5] Read more about CSOs here.

What is Wastewater Treatment?

Wastewater treatment, or sewage treatment, describes the biological, chemical and physical processes used to remove pollutants, nutrients, and suspended solids (including human waste) from the billions of gallons of wastewater produced every day, before the remaining water, called effluent, is returned to the environment. [6] In the United States, these processes are most often performed at central wastewater treatment plants (sometimes abbreviated to WWTP), though approximately 20% of wastewater management is done by decentralized, onsite systems like septic systems and cesspools, and does not always include treatment. Treatment plants treat incoming wastewater to different degrees depending on inhouse technology, and/or state and local water regulations, but the general idea is for plants to reduce the amount of pollutants in the wastewater effluent to a level that the environment can handle. [7] Read more about what happens when wastewater is not properly treated later in this article.

How Does Wastewater Treatment Work?

Once sewage gets to the treatment plant, it is typically treated using physical, chemical and biological treatment methods. The different stages of treatment are referred to as primary, secondary, and tertiary treatment; however, not all treatment plants conduct all three.

Primary Treatment

Primary treatment consists only of separation of liquids from solids. Typically, the raw wastewater first passes through grates and screens to remove large pieces of trash and debris. The wastewater then flows to large basins called clarifiers where both floatable and settleable solids are removed. Floatable solids are skimmed off the top of the water and settleable solids are removed from the bottom of the clarifier. The settleable solids are called primary treatment sludge. The basic principle at work here is to use gravity and density differences to allow water and solids to separate by slowing the flow down. Sometimes chemicals such as ferric chloride and/or anionic polymers are added to the clarifier to promote the agglomeration (clumping together) and settling of fine particles. This may be referred to as advanced primary treatment.

Waste-water-and-sewage-treatment-process 5050c695bb73f w1500.jpg
Figure 1. Wastewater and sewage treatment process. Image courtesy of Hamilton Township Municipal Authority.

While primary treatment removes approximately 60% of suspended solids from wastewater [8], the wastewater still contains substantial concentrations of suspended organic waste, and both the solids and the water contain very high concentrations of fecal coliform and other types of bacteria, including potential pathogens. Any chemicals poured down the drain (including those in cleaning products, body cleansers, etc) will also not be captured or treated in this process. Further solids and bacteria removal occurs during secondary treatment.

Secondary Treatment

Secondary treatment utilizes special strains of aerobic bacteria (bacteria that need oxygen to grow) to break down the organic waste left after primary treatment. The two most common processes that use aerobic bacteria are the trickling filter and activated sludge processes. In a trickling filter, wastewater is sprayed over a bed of rocks or other media that are coated with a slimy layer of bacteria that eats organic waste. Alternatively, the activated sludge process involves mixing wastewater with a bacteria-containing sludge and air, and is then allowed to settle in a secondary treatment clarifier. As in the trickling filter, the bacteria eat a large percentage of the fine organic waste. The activated sludge process is more efficient than the trickling filter, but also more complicated and energy intensive. Through these processes, secondary treatment is able to remove more than 90% of suspended solids from the wastewater. [9] Wastewater then overflows from the secondary treatment clarifier to the outfall pipe or to tanks where it is stored for further treatment and use as reclaimed water (more on wastewater recycling later).

Settled solids from the secondary treatment clarifier are combined with solids from the primary clarifier and are sent to large, closed tanks called sludge digesters, where they are kept for 20-30 days as they break down. [10] In the digesters, anaerobic (low-oxygen) bacteria eat organic matter in the sludge and produce methane gas, which can be used in heating or to generate power for the treatment plant. The digested solids are then dewatered (water is removed from the solids by filters) and the resulting biosolids may then potentially be used as fertilizer, as a soil amendment, or as fuel.

Tertiary Treatment

Tertiary treatment is often used for providing reclaimed water (also sometimes called recycled water or tertiary treated water), which is wastewater that has gone through primary and secondary treatment as well as further treatment by additional filtration and/or chlorination/dechlorination. It is often used for irrigation of parks, golf courses, and general landscaping. It is not potable, meaning it isn’t suitable for drinking.

Advanced Treatment (for Direct or Indirect Potable Reuse)

Wastewater can also be treated to a higher standard than reclaimed water. A number of advanced treatment processes can be used to convert secondary or tertiary treated wastewater into water that is clean enough to drink. The processes used in advanced treatment include microfiltration and reverse osmosis, and have been implemented in places like Orange County and San Diego, California. Read more about recycled water and wastewater reuse later in this article.

Current Use

While approximately 20% of US households use decentralized wastewater systems like septic, the majority of Americans are reliant on central sewers and wastewater treatment plants to manage their sewage and other wastewater. [11] Currently, that means 62.5 billion gallons of wastewater are being treated by centralized wastewater treatment plants every day, according to an annual infrastructure report card from the American Society of Civil Engineers (ASCE). [12] As of 2021, the United States has over 800,000 miles of public sewer lines and 500,000 miles of private sewer laterals which transport wastewater to the more than 16,000 active wastewater treatment plants nationwide. These treatment plants are operating, on average, at 81% of their designed capacities. [13] A 2018 study from the Pew Research Center estimates 86% of US population growth will occur in urban and suburban areas [14], and as these populations increase, our wastewater treatment plants will need to accommodate increasingly larger portions of US wastewater demand. [would be great to add estimates of primary vs secondary vs tertiary vs advanced]

Worryingly, the ASCE report found that 15% of US treatment plants (approximately 2,400 facilities) have already reached or exceeded their design capacities, and many plants are reaching the end of their lifespans. [15] The majority of wastewater treatment plants have been designed with an average lifespan of 40 to 50 years. This means that the plants that were constructed around the passage of the 1972 Clean Water Act are now approaching the end of their service life expectancy. [16]

Significant investment in our wastewater infrastructure from all levels of government is necessary to try to make up for years of neglect that allowed sewer lines and wastewater treatment plants to fall into disrepair, causing at least 23,000 to 75,000 sewage spills and overflows, not including sewage backups into buildings, in the US each year according to EPA. [17] Furthermore, we must repair and rebuild this critical infrastructure with climate resiliency in mind (more on this later).

Problems with Wastewater Treatment

How do Wastewater Treatment Plants fail?

A major cause behind treatment plant failure is mechanical failure due to age. As mentioned above, the average lifespan of a wastewater treatment plant is between 40 and 50 years. [18] After the passage of the 1972 Clean Water Act, treatment plants and other wastewater infrastructure were built to comply with the new law. Now, nearly 50 years later, these plants are at the end of their service life and must be upgraded.

Failure to upgrade and maintain these plants has serious economic consequences on top of the environmental and public health consequences discussed in the next section of this article. According to the ASCE report card, if operation and maintenance goes unaddressed, systems failures could cost homeowners between $3,000 and $7,000. [19] (More on this later.)

Wastewater treatment plants can also fail as a consequence of sewer line failures. Sewer systems can fail in a number of ways, from blockages and clogged pipes due to build-ups of fat and grease, to tree roots growing through and cracking sewer pipes. Sometimes, sanitary sewers are inappropriately connected to stormwater sewers, or vice versa, in something called a misconnection which allows flows of stormwater and wastewater to mix and overwhelm the system. Furthermore, as sewer systems age and fall into disrepair, stormwater and groundwater can also enter sanitary sewer lines through cracks or joints as inflow and infiltration. [20] Read more about types of sewer line failures here.

Often, sewer line failures result in sewer system overflows, or SSOs, in which wastewater flow moves backwards to flood basements, homes, streets, and surface waterways with sewage containing potentially harmful, disease-causing pathogens and other contaminants. EPA estimates there are at least 23,000 to 75,000 SSOs in the US each year, not including sewage backups into buildings. [21]

When sewer systems exceed their capacity, wastewater flow can also move forward to the wastewater treatment plant, which is only able to handle a certain volume of water at any given time. When this treatment capacity is surpassed, poorly treated (or even untreated) wastewater will be released into local waterways to try to avoid backups into streets and homes.

EPA reports that between 2012 and 2016, improvements were made to more than 180 of the large sanitary sewer systems in the United States. These systems typically manage over 10 million gallons of wastewater per day and are highly susceptible, even prone, to episodic SSOs. [22] However, according to the ASCE report card, that progress has slowed in recent years. [23] As discussed throughout this article, significant investments are needed to address these gaps.

How do Wastewater Treatment Plants pollute coastal waters?

The primary concern with aging, neglected wastewater infrastructure is sewage spills, which are a major problem in the United States. Sewage spills can result from any of the failures discussed above, and these failures will likely be exacerbated by climate change (more on this later). In 2019, for example, Florida’s Department of Environmental Protection reported 2,779 wastewater spills in the state, a significant increase from the 1,282 reported spills in 2007. Florida spills spiked in 2017 following Hurricane Irma, to a peak of 3,452 reported wastewater spills that year. [24] (Read more about Florida in the Case Study section of our Sewer Systems article.)

Overflows can also happen when sewer systems take on stormwater and exceed their capacity, which in turn overwhelms treatment plants, causing them to discharge poorly treated (and even untreated) wastewater directly into local waterways.

Human health impacts from sewage spills are a serious and growing concern as spills become more frequent. Sewage pollution contains many harmful contaminants, including several types of disease-causing pathogens that can lead to lung and intestinal infections, symptoms like fever, diarrhea and vomiting, as well as even more dangerous diseases like typhoid fever and cholera. [25] High concentrations of bacteria like enterococcus, which is often used as an indicator of sewage pollution in water quality sampling, can cause serious infections when exposed to open wounds. [26] These are just a few examples of the health risks that sewage pollution poses. In the words of Marilu Flores, Surfrider’s regional manager for Florida and Puerto Rico: “If you have underlying health conditions, if you are immunocompromised, the sky’s the limit on how some of this bacteria can affect you.” [27]

Sewage spills, and the high concentrations of nitrogen and other nutrients sewage contains, also cause a suite of environmental problems in coastal ecosystems. Nitrogen acts as a fertilizer both on land and in the water, causing algae populations to skyrocket in events called algal blooms. These increased populations of algae eventually die and sink to the bottom of the water body to decompose, which depletes the dissolved oxygen in the water and often causes mass die-offs of fish, turtles, manatees and other aquatic life from the lack of oxygen and reduced food sources. When this happens on a large scale, affected areas are called dead zones. Unfortunately, even "proper functioning" wastewater treatment plants can pollute marine waters with high levels of nitrogen. For instance, in the Puget Sound, there are concerns regarding wastewater treatment plants failing to filter nitrogen and other nutrients before discharging into the Sound. The discharge levels are so high that the WA Department of Ecology is taking action to push for stronger regulations on treatment plants to limit nitrogen releases.

Drops in dissolved oxygen are not the only consequence of eutrophication, or the over-enrichment of nitrogen and other nutrients in waterways. In tropical regions, algae can cover reefs, starving corals of sunlight and oxygen. The subsequent, sudden loss of reef habitat has repercussions for fish, with one study finding 83% of the most abundant species either severely reduced or completely eliminated following an algal bloom in the Gulf of Oman. [28] In more temperate regions, high levels of nitrogen in the water lead to the decline of seagrass beds, which provide nursery habitat for many important fisheries, as well as provide critical storage for atmospheric carbon as a blue carbon ecosystem. Eutrophication can also lead to an increase in harmful algal blooms and red tides that produce toxins that contaminate shellfish, cause fish kills and other sea life to die, and even threaten human health with a variety of mild to severe symptoms.

Threats to Wastewater Treatment Plants from Climate Change

We are becoming increasingly familiar with the consequences of climate change and sea level rise, including changing weather patterns and increased intensity and frequency of strong coastal storms. What many might not be aware of is how these changing conditions increase the pressure placed on our wastewater and sewage infrastructure. This increased pressure will likely mean more sewage spills and failures in the future if we don’t make significant investments now to prepare our water infrastructure to become more resilient in the face of climate change.

A major concern when it comes to the impacts of climate change on wastewater treatment plants is increased frequency of sewer system overflows, which can overwhelm treatment plants and cause them to discharge undertreated or even untreated wastewater into surface water bodies. Therefore, climate threats to sewer lines are also threats to wastewater treatment plants.

Flooding associated with extreme weather events, which are expected to increase in intensity and frequency as our climate warms, poses a number of threats to our wastewater infrastructure. When these storms hit, cracked and corroded sewer pipes, manhole covers, and other parts of the wastewater infrastructure system allow rain and stormwater runoff to enter sanitary sewers. Sanitary sewers are only designed to hold wastewater, so the sudden influx of stormwater can quickly overwhelm the sewer system and cause overflows of untreated sewage into local waterways. [29] In cities with combined sewer systems, where both sanitary wastewater and stormwater flow into the same sewers, overflows happen even more quickly. [30] Read more about Combined Sewer Overflows here.

SSOs, and their associated impacts on treatment plants, may become more common even in dry weather. Many coastal regions in the US are already experiencing recurrent flooding at high tide during events aptly called high-tide flooding or sunny day flooding. Research shows that high-tide flooding events will become more common in areas already experiencing high-tide flooding, and will expand to currently unaffected areas as sea levels rise. [31]

Likewise, in low-lying coastal areas, sea level rise can cause seawater to infiltrate old pipes, through storm drains or compromised sanitary sewers. [32] Projected levels of sea level rise are also set to raise water tables, elevating the depth of permanently saturated soils and potentially flooding sewers with groundwater, even inland. This is already happening in Honolulu, Hawai’i, where a study has found direct evidence of tidally-driven groundwater flooding of the city’s wastewater infrastructure. [33] According to a study conducted across California, a coastal region with diverse topography and climate, 1 meter of sea-level rise is expected to expand the reach of areas flooded from below by approximately 50 to 130 meters inland, with low-lying coastal communities most at risk. [34] [35] The end result of groundwater flooding is the same as during rain or storm events: sewer systems get overwhelmed and discharge untreated sewage into local waterways. The risks to human health and the environment from sewage pollution remain the same as well, and aging, neglected infrastructure is only exacerbating those risks.

Sea level rise also directly threatens wastewater treatment plants. Because the flow of most sewer systems is driven by gravity, many wastewater treatment plants are located at low points - which, in coastal areas, often means right near the ocean. A 2018 study found that a sea level rise of approximately 0.3 meters, or a little less than 1 foot, would expose 60 US wastewater treatment plants to flooding, affecting 4 million people. [36] [37] 2 meters (approximately 6 feet) of sea level rise, the study’s worst case scenario, would compromise 394 treatment plants and affect 31 million people. [38] [39]

Current Regulations

Wastewater treatment is regulated under the federal Clean Water Act, which requires that all wastewater treatment plants use primary and secondary treatment before discharging their water. In some cases, however, sewer agencies have been able to apply for a 301(h) waiver to get permission to discharge their wastewater with less than full secondary treatment.

The Orange County Sanitation District (OCSD) in Orange County, California is an example of an agency that historically received such a waiver. OCSD treated approximately half of their wastewater using secondary treatment and the other half using only advanced primary treatment. The two wastewater streams were then combined and pumped out a 4-1/2 mile-long outfall pipe into the ocean. In 2002, pressure from the Surfrider Foundation, other environmental groups and the general public convinced the OCSD Board of Directors to drop their application for a continued 301(h) waiver. The board then embarked on a multi-year, multi-million dollar upgrade to their facilities to achieve full secondary treatment. The new facilities came online during 2011/2012. Read more about the project here.

The City of San Diego also has a 301(h) waiver for their Point Loma treatment plant that employs only advanced primary treatment. In that case, extensive ocean monitoring has indicated no human health or ecological impacts and the Point Loma site is extremely constrained. So, rather than upgrade their level of treatment at Point Loma, the city is concentrating on increasing the generation and use of reclaimed wastewater produced at other wastewater treatment facilities (including Indirect Potable Reuse) to lessen the discharge of partially treated wastewater from the Pt. Loma facility. In 2014, the city formally approved a 20-year program to produce at least 83 million gallons of high-quality drinking water and therefore reduce their wastewater discharges to the ocean by a corresponding amount.


Advanced Technologies and Recycled Water

When it comes to upgrading wastewater treatment plants that have reached the end of their service lives or are in need of repairs, there are remarkable opportunities to implement widespread and robust wastewater recycling programs.

All water is recycled water, thanks to the natural hydrologic cycle. Precipitation falls to the ground as snow or rain and then eventually flows to rivers, lakes and the ocean. The water then evaporates, rises into the sky, condenses into clouds, and falls back to the earth as rain or snow, completing the cycle. Some rain percolates into underground aquifers where it remains until it feeds into a surface water body at a lower elevation or is pumped out for use. At many points along the way, water is consumed by plants, animals, and humans. Because of the hydrologic cycle, chances are that most, if not all, of the molecules of water that you drink have passed through the bodies of other humans or animals. Through heavy treatment of wastewater, we have an opportunity to mimic this natural cycle and make use of a precious resource.

Much of the water that goes down the drains from showers and sinks in our houses (called greywater) is suitable to be used locally for irrigation purposes. The rest, like sewage, (called blackwater) undergoes conventional primary and secondary treatment processes, typically followed by filtration and disinfection (tertiary treatment). This tertiary-treated wastewater is often referred to as reclaimed water and can be used to irrigate parks, golf courses, cemeteries and other landscaping.

Wastewater can also be treated to a higher standard than reclaimed water. A number of advanced treatment processes can be used to convert secondary or tertiary treated wastewater into water that is good enough to drink. These advanced treatment processes include microfiltration and reverse osmosis (more on these processes here).

Both microfiltration and reverse osmosis pump water through membranes to remove very small particles, including bacteria and viruses. The water may then be disinfected using ultraviolet light, ozone, or chlorine which kill any remaining pathogens in the treated wastewater or effluent. These processes are on display in Orange County, California, where the largest advanced water purification system in the world (called the Groundwater Replenishment System, or GWRS) produces about 100 million gallons per day of high-quality, potable water for Orange County residents. [40] This system has now produced over 353 billion gallons (and counting) of high purity water that exceeds state and federal drinking water standards, and has greatly reduced the flow of partially treated wastewater into the ocean. [41] As mentioned above, the City of San Diego has committed to constructing a similar system at their Point Loma facility. Learn more about Orange County’s wastewater recycling programs in the Case Studies section of this article.

One of the impediments to implementation of wastewater recycling systems, especially those that involve direct or indirect potable reuse of the treated wastewater, has been concern that these projects might represent a risk to public health. In fact, a 1998 National Research Council recommendation was that reclaimed water be used in drinking supplies only as "an option of last resort." This is no longer the case. With advances in technology and scientific understanding of how reliable these recycling technologies actually are, attitudes are shifting and wastewater recycling is finally being seen for the great opportunity it presents. In early 2012, the National Research Council released a new report which says that reclaimed water can contribute a growing portion of the nation's drinking water supplies and is as safe as conventional sources. "We can really say that there is no difference from the risk standpoint," said Jorg Drewes, a water reuse expert on the report’s panel. "You can have a supply that is as safe as the current drinking water supplies." As Ben Grumbles, then-president of the US Water Alliance who now serves as Maryland’s Secretary of the Environment, said about the report: “In essence, there is no wastewater, just wasted water.” [42]

Water recycling simultaneously addresses a water supply problem, a waste disposal problem, and an ocean pollution problem. The 100 million gallons per day of wastewater in Orange County that is now being converted into high purity drinking water is 100 million gallons per day of water that doesn’t need to be imported from northern California or the Colorado River. It is also 100 million gallons of wastewater that no longer flows into the ocean off Huntington Beach.

Understanding and implementing water recycling requires a paradigm shift from thinking of “used” water as wastewater (something to get rid of as cheaply as possible) to thinking of it as the valuable, and limited, resource it is. Existing, proven technology can be used to convert water that has previously been flushed down your toilet into drinking water, that meets all applicable water quality standards and is likely more pure than most expensive bottled water. Read more in the Case Studies section later in this article.

The main concept here is that water is a natural resource that is too valuable to use just once and then throw away. Check out Surfrider’s Cycle of Insanity and Know Your H2O resources, as well as the Reef Resilience Network’s Wastewater Pollution Toolkit, to learn more.

Policy Actions

Significant investments in repairing and rebuilding wastewater infrastructure are required to address the human health and environmental threats associated with sewage pollution. The nation’s centralized wastewater systems have been neglected for years, decades even, resulting in approximately 900 billion gallons of under-treated sewage being discharged into surface waters every year. [43]

According to a report from the Congressional Research Service, federal capital investment in wastewater infrastructure has fallen considerably in recent history, from a share of 63% in 1977 to less than 9% in 2017. [44] This has created a significant gap between available funding for infrastructure and the capital required to address infrastructure needs. As of 2019, that funding gap amounted to around $81 billion, and because of persistent underinvestment, only 37% of total US water infrastructure capital needs were met. [45]

Most of this deficit in wastewater infrastructure spending is shouldered by states and local governments, and costs of infrastructure improvements are growing. Capital projects and operation and maintenance expenses increased from approximately $20 billion in 1993 to $55 billion by 2017. [46] Wastewater utilities are actually responsible for the majority of their expenses, but many utilities and local governments look to federal funding, particularly for larger projects. [47] Still, a number of states and communities are already investing in upgrades to their wastewater infrastructure, replacing old, cracked and corroded pipes with new sewer lines, and updating antiquated pump stations to be more efficient. The city of Fort Lauderdale, FL, for example, has a $65 million project underway to install nearly 50,000 feet of new sewage pipe to stop spills. [48] Read more about that project here.

Since 1987, the US Environmental Protection Agency (EPA) has provided funding for states to upgrade their wastewater infrastructure through the Clean Water State Revolving Fund (CWSRF). States match 20% of the funding from CWSRF loans and grants, which can be used for upgrading centralized sewer systems, wastewater treatment plants, decentralized wastewater systems like septic tanks, stormwater management efforts, as well as other projects focused on clean water. [49]

EPA is also responsible for conducting the Clean Watersheds Needs Survey (CWNS), which assesses the need and cost required to meet water quality goals set in the Clean Water Act. The survey evaluates needed investments in a number of categories, including sewer replacement/rehabilitation, infiltration and inflow correction, and stormwater management. The CWNS is supposed to be conducted every four years, but due to a lack of EPA funding in recent years, the last survey was released over nine years ago in 2012.

Congress is responsible for EPA’s budget, which funds both the Clean Water State Revolving Fund and Clean Watersheds Needs Survey. The 2021 INVEST in America Act, which passed the House of Representatives on July 1, 2021, would authorize much-needed funding for wastewater infrastructure investments. Included in the House version of the bill was the Water Quality Protection and Job Creation Act, which authorizes $8 billion annually over five years to the EPA CWSRF, and a Climate Resilience Provision that requires any CWSRF-funded infrastructure projects to complete a climate resiliency assessment and be designed and constructed to withstand climate change impacts. As of writing (July 2021), the bill is awaiting a vote in the Senate.

Surfrider created our Stop Sewage Pollution campaign to help improve our wastewater infrastructure and ensure that all sewage in the US is adequately collected and treated to protect public and environmental health. This effort includes tracking state and federal policies like the CWSRF and BEACH Act, as well as operating the Blue Water Task Force, a national network of volunteers monitoring bacteria levels at more than 450 ocean, bay, estuary and freshwater sampling sites across the US. Read more about how to get involved in our Stop Sewage Pollution campaign here.

Personal Actions

There are many actions we all can take to care for our wastewater systems, regardless of type. Good practices include:

  • Only flush the three P’s: pee, poop, and (toilet) paper.
  • Conserve water inside the house.
  • Don’t pour cooking grease or oils down the drain; instead, collect it in a container, freeze it, and throw it in the trash.
  • Check the ingredients and opt for natural personal care products (like soaps and sunscreen) when possible.
  • Try to avoid cleaners with petroleum additives or fillers, as they act like grease to cause blockages once they enter a wastewater system.
  • Skip the powder detergents for the same reason.

Reducing stormwater and dry-weather urban runoff goes a long way to prevent sewer overflows, as well as discharges from overwhelmed wastewater treatment plants. Use as little water as possible. Don't over-water your lawn, and adjust your sprinklers to avoid watering the pavement (it won't grow). Consider installing an Ocean Friendly Garden to increase infiltration (rainwater that is absorbed into the ground) and reduce runoff entering sewer systems. Ocean Friendly Gardens apply something called the watershed approach to allow the soil to act like a sponge, soaking up rainwater to prevent flooding during storms and providing filtration to keep pollution from reaching groundwater and surface waterways. Check out some examples of Ocean Friendly Gardens in Long Island, NY here.

Case Study: Orange County, CA

Advances in wastewater treatment technologies present an incredible opportunity for expansive, robust wastewater recycling programs, as well as opportunity for creative uses for recycled water reserves.

An example of a community making the most of this opportunity is Orange County, California, home of the Groundwater Replenishment System. Every day, about 100 million gallons of wastewater goes through primary and secondary treatment at Orange County Sanitation District’s “Plant 1” and is then piped to a facility next door operated by Orange County Water District. That treated wastewater is then processed through three additional purifying steps, using microfiltration, reverse osmosis, and advanced oxidation processes (more on these processes here). Following that additional treatment, the water is pumped about 15 miles to spreading basins where the water is allowed to percolate through natural sand into underground aquifers (the replenishing part of the Groundwater Replenishment System). Wells can then draw the purified water out of the aquifer to be used as a fresh water supply. This system can be thought of as a continuous loop or a “man made” water cycle. [50]

Orange County’s Groundwater Replenishment System is the largest advanced water purification system in the world, and has produced more than 353 billion gallons of high-quality drinking water (and counting!) since it came online in January 2008. [51] A project ten years in the making, the premise of GWRS was conceived in the mid-1990’s to address problems facing the county on multiple fronts: the need for additional wastewater infrastructure, increasing issues with saltwater intrusion into groundwater reserves and wells, and the expansion of drinking water treatment facilities. On top of these concerns, the state of California had just come out of a severe drought, and scientists were (correctly) projecting that droughts would become more common in the near future. All of these pressures came together to spur innovation: the Orange County Sanitation District (OC San) and Orange County Water District (OCWD) came together to implement advanced purification processes to convert wastewater into high-quality drinking water to recharge local aquifers. [52]

The Groundwater Replenishment System has become a model for wastewater recycling for potable reuse, but it is not the only water reuse project administered by Orange County Water District. OCWD’s Green Acres Project (GAP) addresses irrigation needs by providing recycled water for parks, schools and golf courses, as well as other non-potable uses like toilet flushing and cooling at power plants. [53] To combat the increased saltwater intrusion mentioned above, OCWD’s Water Factory 21 injected recycled water into 23 wells around Fountain Valley and Huntington Beach. [54]

In addition to these other water reuse projects, Orange County is in the process of expanding the Groundwater Replenishment System as part of a project they call the GWRS Final Expansion. The expansion promises an added output of 30 million gallons per day, which means that the completed system will produce 130 million gallons of high-quality, potable water for groundwater replenishment every day. Construction is expected to be completed by 2023.

Additional Resources

1. ASCE’s Report Card for America’s Infrastructure (Wastewater) 2. Reef Resilience Network’s Wastewater Pollution Toolkit 3. USGS A Visit to a Wastewater Treatment Plant


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  22. Everitt Rosen. (2021). Major spills from Florida’s sewage treatment plants are on the rise - and so are the storms that can cause aging pipes to burst.
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  24. Everitt Rosen. (2021). Major spills from Florida’s sewage treatment plants are on the rise - and so are the storms that can cause aging pipes to burst.
  25. Everitt Rosen. (2021). Major spills from Florida’s sewage treatment plants are on the rise - and so are the storms that can cause aging pipes to burst.
  26. Everitt Rosen. (2021). Major spills from Florida’s sewage treatment plants are on the rise - and so are the storms that can cause aging pipes to burst.
  27. Everitt Rosen. (2021). Major spills from Florida’s sewage treatment plants are on the rise - and so are the storms that can cause aging pipes to burst.
  28. Ella Davies. (2010, October 8). Toxic algae rapidly kills coral.
  29. US EPA. (2021, July 10). Sanitary Sewer Overflows (SSOs)
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  31. Thompson, P. R., Widlansky, M. J., Hamlington, B. D., et al. (2021, June 21). Rapid increases and extreme months in projections of United States high-tide flooding.
  32. McKenzie, T., Habel, S., Dulai, H. (2021, March 12). Sea-level rise drives wastewater leakage to coastal waters and storm drains.
  33. McKenzie, T., Habel, S., Dulai, H. (2021, March 12). Sea-level rise drives wastewater leakage to coastal waters and storm drains.
  34. Befus, K. M., Barnard, P. L., Hoover, D. J., et al. (2020, August 17). Increasing threat of coastal groundwater hazards from sea-level rise in California.
  35. US Geological Survey. (2020, September 30). https://www.usgs.gov/center-news/new-model-shows-sea-level-rise-can-cause-increases-groundwater-levels-along-california-s?qt-news_science_products=1#qt-news_science_products New Model Shows Sea-level Rise Can Cause Increases in Groundwater Levels along California’s Coasts]
  36. Hummel, M.A., Berry, M.S., Stacey, M.T. (2018, March 24). Sea Level Rise on Wastewater Treatment Systems Along the U.S. Coasts.
  37. Emily Underwood. (2018, May 4). Sea Level Rise Threatens Hundreds of Wastewater Treatment Plants.
  38. Hummel, M.A., Berry, M.S., Stacey, M.T. (2018, March 24). Sea Level Rise on Wastewater Treatment Systems Along the U.S. Coasts.
  39. Emily Underwood. (2018, May 4). Sea Level Rise Threatens Hundreds of Wastewater Treatment Plants.
  40. Orange County Water District. (2021). GWRS Frequently Asked Questions
  41. Orange County Water District. (2021). GWRS Frequently Asked Questions
  42. Dylan Walsh. (2012, January 24). Wasting the Wastewater
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  48. Everitt Rosen. (2021). Major spills from Florida’s sewage treatment plants are on the rise - and so are the storms that can cause aging pipes to burst.
  49. US EPA. (2021, July 3). Learn about the Clean Water State Revolving Fund (CWSRF)
  50. Orange County Water District. (2021). GWRS Frequently Asked Questions
  51. Orange County Water District. (2021). GWRS Frequently Asked Questions
  52. Orange County Water District. (2021). GWRS Frequently Asked Questions
  53. Orange County Water District. (2021). Green Acres Project
  54. Orange County Water District. (2021). Water Factory 21 Brochure