California defines hazardous waste as any waste with properties that make it potentially dangerous to human health or the environment. That definition is broader than federal standards. The state regulates many materials that the U.S. EPA does not, including used oil, fluorescent lamps, batteries, and certain types of treated wood. Whether you’re a homeowner cleaning out your garage or a business managing industrial byproducts, the rules are set by the Department of Toxic Substances Control (DTSC) under the Hazardous Waste Control Law.
How California Classifies Hazardous Waste
A waste becomes hazardous in California through two paths: it either appears on a specific list of known hazardous materials, or it exhibits one of four dangerous characteristics. The person or business generating the waste is legally responsible for making that determination.
The four characteristics are:
- Ignitability: The waste can catch fire easily. Solvents, certain paints, and fuel residues fall into this category.
- Corrosivity: The waste is highly acidic (pH below 2) or highly alkaline (pH above 12.5). Drain cleaners, battery acid, and industrial alkaline solutions qualify.
- Reactivity: The waste is unstable, explosive, or releases toxic gases when mixed with water. Materials containing cyanide or sulfide compounds are common examples.
- Toxicity: The waste contains harmful substances at concentrations above legal limits. This is where California diverges most sharply from federal rules.
California’s Stricter Toxicity Standards
The federal government uses one toxicity test, called the TCLP, to determine if a waste is hazardous. California uses that same test but adds two additional thresholds: the Soluble Threshold Limit Concentration (STLC) and the Total Threshold Limit Concentration (TTLC). These California-specific limits are often far more restrictive.
For lead, the federal threshold is 5.0 mg/l in a leaching test. California’s STLC for lead is also 5.0 mg/l, but the state adds a total concentration limit of 1,000 mg/kg in the waste itself. For mercury, California sets the STLC at just 0.2 mg/l and the TTLC at 20 mg/kg. The result is that many wastes pass federal standards but fail California’s, making them “non-RCRA” hazardous waste, a category that exists only under state law. Used oil is one of the most common examples: California requires it to be managed as hazardous waste regardless of whether it shows hazardous characteristics.
Common Household Hazardous Waste
If you’re a California resident, many items in your home are legally classified as hazardous waste once you discard them. The DTSC’s list includes antifreeze, batteries, drain cleaners, electronic devices (TVs, monitors, cell phones), glue and adhesives, household cleaners, oven cleaners, paints, pesticides, pool chemicals, solvents, used oil, anything containing asbestos, and mercury-containing items like thermometers and fluorescent light bulbs.
You cannot throw these in the regular trash or pour them down a drain. Most counties operate household hazardous waste collection facilities where residents can drop off these materials for free. Used motor oil can also go to auto parts stores that accept it or to a dedicated used oil collection center. Residents can transport up to 55 gallons of their own used oil to these locations without needing special permits.
Electronic Waste
All unwanted electronic devices are classified as hazardous waste in California. This includes CRT televisions, LCD and OLED monitors, plasma screens, laptops, tablets, desktop computers, printers, cell phones, VCRs, portable DVD players, and radios. These devices contain lead, mercury, cadmium, and other toxic metals in their circuits and screens.
E-waste falls under California’s “universal waste” category, which allows for simpler handling and collection rules compared to other hazardous waste. You can bring old electronics to certified e-waste collectors and recyclers rather than using a hazardous waste hauler.
Universal Waste Categories
California recognizes eight categories of universal waste: batteries, electronic waste, cathode ray tubes (CRTs), CRT glass, lamps (including fluorescent tubes and compact fluorescent bulbs), mercury-containing devices, non-empty aerosol cans, and photovoltaic (solar) modules. Universal waste is hazardous waste, but the handling and transport rules are streamlined so that households and small businesses can manage these items more practically.
Fluorescent lamps are a good example of the California difference. Nationally, they may not be regulated as hazardous in every state, but California classifies them as universal waste because they contain mercury. A single four-foot fluorescent tube contains enough mercury to exceed California’s strict TTLC threshold.
Listed Wastes by Category
Beyond the four characteristics, California maintains a detailed list of specific waste types assigned numerical codes. Some of the most commonly encountered categories include:
- Solvents: Halogenated solvents like chloroform and perchloroethylene (code 211), oxygenated solvents like acetone and ethyl acetate (code 212), and hydrocarbon solvents like benzene and hexane (code 213).
- Asbestos-containing waste (code 151): Any material with asbestos fibers, commonly found in older insulation, floor tiles, and roofing.
- PCB-containing materials (code 261): Polychlorinated biphenyls, once used in electrical transformers and industrial equipment.
- Pharmaceutical waste (code 311): Expired or discarded medications from healthcare facilities.
- Laboratory waste chemicals (code 551): Mixed chemical waste from research and medical labs.
- Dioxin-containing waste (code 801): Waste that may contain dioxins, which are highly toxic even in trace amounts.
California also sets specific concentration thresholds for liquids containing heavy metals. Liquids with arsenic above 500 mg/l, cadmium above 100 mg/l, lead above 500 mg/l, or mercury above 20 mg/l all receive their own waste codes and handling requirements.
Treated Wood Waste
Pressure-treated lumber, the kind commonly used for decks, fences, and utility poles, is potentially hazardous waste in California. Treated wood can contain elevated levels of arsenic, chromium, copper, pentachlorophenol, or creosote. Testing has shown that treated wood samples often exceed California’s TTLC and STLC values for metals, even when the same wood would pass less stringent federal thresholds.
In 2021, California passed Assembly Bill 332, which established alternative management standards for treated wood waste. These rules allow treated wood to be disposed of at certain non-hazardous waste landfills rather than requiring full hazardous waste handling. You don’t need a hazardous waste hauler or a manifest to transport it, but you do need to send it to a landfill that participates in the program. Treated wood still cannot go in a regular curbside trash bin or be burned.
Used Oil and Automotive Fluids
California law requires all used motor oil to be managed as hazardous waste. This covers vehicle crankcase oil, engine lubricants, transmission fluid, and gear oils. The classification applies regardless of whether the oil tests positive for hazardous characteristics, which is stricter than the federal approach.
Businesses that generate used oil must obtain a state or EPA identification number for each site where oil is stored. All containers need tight-fitting lids, and labels must include the words “USED OIL” and “HAZARDOUS WASTE” along with the accumulation start date. If a business hires someone to haul away its used oil, that transporter must be a registered hazardous waste hauler.
Used oil filters with metal housings can be drained and sent for recycling under less strict rules. But filter cartridges without metal housings, sometimes called filter media inserts, must be handled as hazardous waste unless the generator can prove they don’t exhibit hazardous characteristics. Antifreeze, brake fluid, and fuel filters are separate from used oil and have their own disposal requirements.
California-Only vs. Federal Hazardous Waste
The distinction between RCRA waste (federally regulated) and non-RCRA waste (California-only) matters for businesses because it affects which forms, transporters, and disposal facilities are required. Non-RCRA hazardous wastes are materials that meet California’s hazardous waste criteria but not the federal EPA’s. Used oil, universal waste items like fluorescent lamps and batteries, and many mercury-containing devices fall into this category.
For practical purposes, if you’re in California, both types are hazardous waste and both carry legal obligations. The difference shows up in paperwork, facility permitting, and which identification numbers apply. Businesses generating any hazardous waste need a permanent state ID number from DTSC, and generators of RCRA waste also need a federal EPA ID number.