Waste can be broken down into types, based on how the law sees it and how it needs to be processed. Longstanding U.S. laws like 40 CFR part 261.31 define certain types of waste as hazardous. Other regulations define where certain types of waste have to be sent for disposal. Making your way through this maze can be complex, but it doesn’t have to be.

Waste falls into several main types, depending on the system of classification. Figure out where your waste fits into this scheme and you should find it pretty simple to figure out where to take it for disposal. (It’s even easier with our disposal locator!)

Remember, there can be serious legal penalties for illegal dumping; the EPA has ramped up its penalties, doubling the maximum fine since 2016. Now, a civil RCRA violation can run you $70,117 — per violation, per day. Way back in 2013, a failure to make a hazardous waste determination cost WalMart $110 million in penalties. They could afford it, but not everyone has pockets that deep. It’s better to get it right the first time.

In this guide, we’ll go over all the types of waste, look at the ways they can be identified, and talk briefly about the laws that cover them — as well as how to dispose of them. There are three different ways to classify waste, which means the waste management landscape can look complex at first glance. We’ll start with the US regulations that cover specific types of hazardous waste.

Types of hazardous waste

A waste type is hazardous if it shows up on the F, K, P and U lists in title 40 of the Code of Federal Regulations (CFR), Part 261.

The F list

F-list wastes are defined as wastes from non-specific sources. They include:

  • Spent solvent wastes
  • Electroplating and other metal finishing wastes
  • Dioxin-bearing wastes
  • Chlorinated aliphatic hydrocarbons production
  • Wood preserving wastes
  • Petroleum refinery wastewater treatment sludges
  • Multisource leachate from mining or mineral extraction

For this list, we’re talking nasties like halogenated solvents and stripping-bath sludges. You can view the full F-list here.

The K List

The K-list wastes are defined by source rather than by what they’re made of. They cover wastes from 13 specified industries, which are:

  • Wood preservation
  • Organic chemicals manufacturing
  • Pesticides manufacturing
  • Petroleum refining
  • Veterinary pharmaceuticals manufacturing
  • Inorganic pigment manufacturing
  • Inorganic chemicals manufacturing
  • Explosives manufacturing
  • Iron and steel production
  • Primary aluminum production
  • Secondary lead processing
  • Ink formulation
  • Coking (processing of coal to produce coke)

You can view the full K-list here.

The P and U lists

The P and U lists designate unused chemicals as hazardous. To make it onto the P or U lists, a product must:

  • Contain one of the chemicals on the P or U lists
  • The chemical in the waste must be unused
  • Be a commercial chemical product, meaning 100% pure, technical/commercial grade, or the sole active ingredient in a chemical formulation.

The P-list identifies acute hazardous wastes, while the U-list identifies non-acute hazardous wastes, from discarded commercial chemical products. You can view the full P and U lists here. These lists also cover spills and contaminated materials, including contaminated soil.

These laws deal with specifics — they tell you exactly how the government views your 1,2-Benzenedicarboxylic acid, or your spent hexachlorobenzene reactant. But there are hundreds of types of waste on each list. Isn’t there a simpler way to separate out waste so you can get rid of it safely, legally and easily?

The four types of ‘characteristic’ waste

You don’t have to check the ECFR’s exhaustive, and exhausting, lists. Another way to classify wastes is by hazard type. Wastes classified this way are known as ‘characteristic wastes,’ and they break down into:


Does it catch fire easily? This category includes liquids with flashpoints below 140°F, nonliquids that can ignite in specific conditions without flame (as when they’re compressed, for instance) and compressed gasses, which can ignite by friction at the valve or chemically.


Strongly acid or basic wastes that can eat through containers, especially steel containers, and cause intense chemical reactions. This usually means a pH of lower than 2 or higher than 12.5.


Wastes that can cause fires or explosions under normal conditions, like fuels and oxidizing agents. This category also includes wastes that can burn or react to produce toxic gases.


Wastes that are fatally poisonous when consumed, inhaled or absorbed. This includes products like lithium-sulfur batteries that can cause death if swallowed.

If your waste is ignitable, corrosive, reactive, or toxic, it’s hazardous. You can check the name of your waste against the CAL/EPA index if you’re not sure.

Finally, we can break down wastes into nine types based on the class of danger they represent. These are called ‘universal wastes,’ and for most people dealing with smaller amounts of waste this is probably the most useful method of categorization.

The nine types of universal waste

These are based on the nine HAZMAT (HAZardous MATerials) classifications, and cover wastes and other substances and products.

Class 1: Explosives

hazardous material class 1 explosives

This category is subdivided into six types:

1.1: Mass explosion hazard

hazardous material class 1.1 mass explosion hazard

Substances and articles with a mass explosion hazard. A mass explosion is one that affects nearly the whole load simultaneously. This would include dynamite, fulminate of mercury and many other explosives.

1.2: Blast/projection hazard

hazardous material class 1.2 blast projection hazard

Anything with a projection hazard, which may cause objects to fly through the air at high velocity. This includes certain fireworks and some types of firearms ammunition.

1.3: Minor blast hazard

hazardous material class 1.3 minor blast hazard

Minor blast hazards, including some smaller firearms ammunition and many fireworks.

1.4: Major fire hazard

hazardous material class 1.4 major fire hazard

Fire hazards with only minor blast or projection hazards, including propellants and some types of rocket motors.

1.5: Blasting agents

hazardous materials class 1.5 blasting agents

Very insensitive explosives with a mass explosion or major blast hazard, including most modern industrial high explosives.

1.6: Extremely insensitive explosives

hazardous material class 1.6 extremely insensitive explosives

Very insensitive items or substances without a mass explosion hazard.

The higher up the list it occurs, the more dangerous an explosive is; class 1.6 is the least dangerous. 1.1 is considered more dangerous than 1.5 because it’s easier to set off; most modern high explosives are much more powerful than black powder, dynamite or gelignite, but they can’t be detonated by heat, flame, pressure or impact.

Class 2: Gases

Gases are also subdivided, into three categories:

2.1: Flammable gases

hazardous material class 2.1 flammable gases

Gases that ignite on contact with an ignition source, like propane and acetylene.

2.2: Non-flammable gases

hazardous material class 2.2 non-flammable gases

Gases that are not flammable or poisonous. Includes low-temperature gases used for cryopreservation and gases like neon and nitrogen.

2.3: Toxic gases

hazardous material class 2.3 toxic gases

These are gases that are likely to cause death or injury if inhaled, like chlorine and hydrogen cyanide.

This category also includes products charged with gases, like gas cylinders.

Class 3: Flammable Liquids

hazardous material class 3 flammable liquids

Flammable liquids include liquids, mixtures of liquids, and liquids containing solids, that require a low temperature to ignite. Sometimes ignition temperature can be reached during transportation, making these substances dangerously combustible.

Examples include the obvious — gasoline, diesel, aviation fuel — and less-obvious candidates like perfume production byproducts, alcohol and varnishes, as well as some pesticides.

Class 4: Flammable Solids or Substances

Flammable solids are solids that are easy to ignite at low temperatures. They’re broken down into three subcategories:

4.1: Flammable solids

hazardous material class 4.1 flammable solids

Solid substances that are easily ignitable, like metallic magnesium or strike-anywhere matches.

4.2: Substances that spontaneously combust

hazardous material class 4.2 Substances which spontaneously combust

Substances like white phosphorus and aluminum alkyls that can spontaneously combust at normal temperatures and pressures.

4.3: Dangerous when wet

hazardous material class 4.3 dangerous when wet

Substances that emit dangerous gases in contact with water, or that react violently with water, such as metallic sodium.

Class 5: Oxidizing Substances and Organic Peroxides

These substances yield oxygen as a result of chemical reactions, meaning they can cause other substances to burn or explode. They are subdivided into two types:

5.1: Oxidizing substances

hazardous material class 5.1 oxidizing substances

Substances like ammonium nitrate and hydrogen peroxide.

5.2: Organic peroxides

hazardous material class 5.2 organic peroxides

Organic peroxides are often thermally unstable and prone to explode or burn by themselves. Examples include calcium and hydrogen peroxide, potassium perchlorate, and ammonium nitrate fertilizers.

Class 6: Toxic and Infectious Substances

Class six substances break down into two subtypes:

6.1: Poison

hazardous material class 6.1 poison

Toxic substances that cause death or injury to people or animals when they’re swallowed, breathed in, or through skin contact. These include strong acids and bases, anti-knock mixture for engines, cyanide, and teargas.

6.2: Biohazard

hazardous material class 6.2 biohazard

Infectious substances transmit infections, and include materials known or presumed to contain pathogens (bacteria, viruses, fungi), such as surgical and medical waste and biological cultures.

Class 7: Radioactive

hazardous material class 7 radioactive

Radioactive hazardous waste emits ionizing radiation (radiation that ionizes other atoms when it hits them) by radioactive decay. It’s defined by certain radioactivity concentration and total radioactivity values, and includes fission products, yellowcake from uranium processing, uranium hexafluoride, and radioactive isotopes. It also includes medical waste like radiography byproducts and the medical supplies (gowns, syringes, swabs) used in high-dose radiotherapy. Some medical waste, like other wastes, will be in multiple hazard categories.

Class 8: Corrosive Substances

hazardous material class 8 corrosive

Corrosives cause chemical reactions that degrade other substances when they come into contact. They eat their way through containers, and can do the same to people and animals if they come into contact. They include battery acid, formaldehyde and strong acids and bases.

Class 9: Miscellaneous Dangerous Substances and Articles

hazardous material class 9 miscellaneous dangerous substances

If it’s dangerous, but not covered by the other eight categories, it’s here. This class includes substances that are transported at high temperatures, dangerous to the environment, carcinogenic, aviation-regulated substances and a lot of others. It covers blue asbestos, fuel cell and internal combustion engines, vehicles, plastics molding compound and polychlorinated biphenyls.

Universal wastes fall into one of three packing groups, depending on how serious a threat they pose.

Packing Group I: Very dangerous, requiring a lot of protective packaging and sometimes refrigeration or other specialized transportation and handling. Some combinations of different classes of dangerous goods in the same container or on the same vehicle are forbidden if one of them is in packing group 1.

Packing Group II: Medium danger, requiring protective packaging but less specialized handling.

Packing Group III: Minor danger, relatively little specialized packaging required.

Each type of hazardous material will have different requirements for each packing group, based on the hazard they present.

What about non-hazardous waste?

Not all waste is designated hazardous. Waste is defined as non-hazardous if it’s not regulated under Subtitle D of the Resource Conservation and Recovery Act (RCRA). And some trash is, well, just trash.

That doesn’t mean its disposal isn’t regulated. Unauthorized dumping of even non-hazardous waste can earn you fines ranging from $4,000 per offense (non-hazardous waste, on-the-spot fine not issued by the EPA) — all the way up to $1,000,000 and a $120,000-a-day rolling fine for corporations with strict liability. Seeking to avoid the fees for legitimate waste dumping doesn’t make sense against this background.

It also doesn’t mean it’s risk-free. Designated hazardous wastes are hazardous in specific ways that require special treatment, but ordinary industrial, business or even household waste can pose environmental, infectious and other risks.

Consider universal waste too: led lights, mercury thermometers, batteries. You can accumulate universal waste on-site for up to a year, but its disposal is regulated and there are still serious fines for mishandling or mislabeling it.

How should you dispose of your waste?

Some waste has to be disposed of in highly-specific ways — radioactive waste, for instance, is tightly regulated and facilities for its disposal are few and far between. But many types of waste are catered for more widely.

Federal regulations impose disposal standards, which lay out permissibility, method and location of waste disposal: whether, where and how you can get rid of it. Almost all hazardous waste is covered by the RCRA, which mandates that hazardous waste can’t be landfilled or added to standard waste streams until it’s been treated to bring it within acceptable limits for things like ignitability and toxicity.

There are also strict regulations controlling how long waste can remain onsite. Large quantity generators must move hazardous waste within 90 days; smaller businesses have six months to accumulate and transport their waste.

At first glance this seems a reprieve, but it can be a poisoned chalice; small operators want to keep their waste disposal costs down so they fill containers as much as possible and wait as long as they can before disposal, but the most common cause of citations for hazardous waste is failure to record the commencement date on the label. Using an unauthorized container can attract a $9,000 fine; so can overfilling a container.

States and cities have their own rules too. For example, in most states, ‘used oil’ is regulated as ‘used oil,’ but in California it’s ‘non-RCRA hazardous waste’ and regulated very much like hazardous waste.

So you need specifics tailored to your location or you won’t get the full picture. Consider looking for a professional waste handler in your state, who will be up to speed with your needs.


Disposing of your waste doesn’t have to be a huge headache. But it will become one if you don’t do it right. Federal and state penalties, lost business time and reputation, and unnecessary stress all come with not planning your waste disposal as part of your normal operations. If your waste is classed as hazardous the situation is even more serious.

If you’re sitting on a one-off lot of waste from an unusual project and you’re not sure what to do with it, look up a local waste management company. If you’re generating significant quantities of the same type of waste, it’s smart to set up waste streams, managing waste right through from production to final disposal and integrating partners, suppliers and clients. We can help you with this.

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