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OSHA Chemical Storage Requirements: How Employers Can Stay Compliant

How OSHA Classifies Hazardous Chemicals

OSHA defines a hazardous chemical as any substance that presents a physical or health hazard in the workplace. Hazards fall into two main groups: physical hazards; like flammables, oxidizers, or reactive substances; and health-related hazards, such as toxins, corrosives, and carcinogens. Once a chemical is classified as hazardous, employers are required to meet specific storage, labeling, training, and documentation standards.

Employers are not responsible for hazard classification. Manufacturers or importers handle the classification process and send each hazardous chemical with a Safety Data Sheet (SDS). Employers need to keep those SDSs on hand, make them easy to access, and build a chemical inventory that reflects everything in use. That inventory is what drives the labeling, storage setup, and employee training tied to each material.

OSHA Standards That Govern Chemical Storage

OSHA regulates chemical storage through several workplace safety rules, most of which fall under its hazardous materials standards. Requirements vary based on the chemical’s type, the amount kept on site, and the storage setup.

For flammable and combustible liquids, the main standard is 29 CFR 1910.106. It outlines how these materials can be stored indoors and when a flammable storage cabinet or dedicated room is required. Key limits under this standard include:

Up to 25 gallons of flammable liquid can be stored outside of an approved cabinet
An approved cabinet can hold up to 60 gallons of Category 1–3 flammables
Only three cabinets are allowed per fire area unless the building meets additional fire protection criteria

Compressed gases are primarily covered under 29 CFR 1910.101, which sets general requirements for safe handling and storage. For example, cylinders need to stay upright, secured, and protected from high heat, ignition sources, and incompatible chemicals. Oxygen and fuel gases also require physical separation of at least 20 feet or a rated barrier.

Other sections of the OSHA standards may apply depending on the chemical and how it's used:

29 CFR 1910.1200 for hazard communication and labeling
29 CFR 1910.119 for Process Safety Management if threshold quantities of highly hazardous chemicals are present
29 CFR 1910.120 for emergency response protocols involving hazardous substances

Each standard addresses a different aspect of risk. Employers need to evaluate their chemical use, quantities, and storage setup to determine which rules apply.

Quantity Limits and Storage Thresholds

OSHA applies specific chemical storage rules based on how much hazardous material is stored in one area. Certain thresholds trigger requirements for fire-rated cabinets, upgraded protection, or physical separation of materials.

No more than 25 gallons of Category 1 flammable liquids can be stored outside of a cabinet or storage room. For Categories 2–4, the limit increases to 120 gallons when stored in approved containers.
An approved flammable storage cabinet can hold up to 60 gallons of Category 1–3 flammable liquids or up to 120 gallons of Category 4 liquids. No more than three cabinets are allowed in a single fire area. In general industry settings, additional groups of up to three cabinets may be permitted if they are separated by at least 100 feet.
Storing larger quantities calls for a dedicated flammable liquid storage room. That room needs to meet defined construction, fire-resistance, and ventilation standards under 1910.106(d)(4).
Incompatible materials such as flammables stored near oxidizers, or acids next to bases, require physical separation to prevent reactions. OSHA has cited employers for storing reactive chemicals too close together, even in small amounts.
Containers placed in nearby rooms or connected spaces may be treated as part of the same fire area. When in doubt, it's safer to treat volumes across adjacent areas as cumulative.

How to Store Incompatible Chemicals Safely

Certain chemicals can react dangerously if they mix. Storing them too close together raises the risk that they’ll come into contact if a container leaks, breaks, or spills. Common examples include:

Acids stored near bases
Flammables placed next to oxidizers
Bleach kept alongside ammonia or acidic cleaners

Even a small spill can trigger a reaction if the wrong materials mix.

OSHA doesn’t set fixed distances for storing incompatible chemicals, but it does expect employers to identify separation needs based on each product’s Safety Data Sheet. Most SDSs include a list of materials the chemical should not be stored near.

That information should guide how storage areas are arranged and how physical separation is applied. Options include:

Separate cabinets
Barriers between containers
Designated storage zones for higher-risk substances

OSHA has cited employers under the General Duty Clause for storing incompatible chemicals in ways that present a clear risk. In many of those cases, enforcement relied on manufacturer guidance or industry standards—such as a 20-foot separation or the use of a rated barrier.

Labeling Rules That Apply Beyond the Manufacturer’s Container

Any time a hazardous chemical is poured into a secondary container, that container needs a label. It doesn’t have to match the manufacturer’s label exactly, but it does need to identify the chemical and describe its hazards clearly enough for employees to recognize the risks.

A label isn’t required if the container is used only by the person who transferred the chemical and stays under that person’s direct control. The exemption applies only to containers intended for immediate use—not to anything left unattended, stored, or handled by others. Anything stored, shared, or left unattended needs to be marked. Employers can label containers using the full chemical name along with a brief description of the hazards or they can use NFPA or HMIS labeling formats, so long as employees have been trained to understand them.

Spill Prevention and Secondary Containment

Some OSHA standards address spill risks tied to how chemicals are stored, moved, or transferred during routine work.

Spill Prevention

Under 29 CFR 1910.106(e)(2)(ii), employers handling flammable or combustible liquids in quantities greater than five gallons are expected to use control measures that prevent those liquids from escaping during transfer. Common options include drip pans placed under spouts, curbs that keep spills contained, or sloped floors that direct liquid away from work areas.

Outdoor storage is addressed in 29 CFR 1910.106(d)(6)(iii).To keep a spill from reaching a building, the ground should slope away from structures or be bordered by a curb that blocks the flow. If rainwater enters the storage area, it can carry spilled chemicals beyond the intended containment zone. Drainage needs to prevent that from happening.

Secondary Containment

If a container holding hazardous material leaks, the spill needs to stay inside the storage area. That’s the point of secondary containment—extra space or equipment that keeps the chemical from reaching drains, walkways, or other containers.

EPA regulations under 40 CFR 264.175 lay out the standard most facilities follow. For hazardous waste storage areas, the containment system needs enough capacity to hold all the liquid from the largest container in the group or ten percent of the total volume stored—whichever is greater.

Spill pallets, concrete curbs, and sump systems are all common ways to meet that requirement. When drums or totes are stored side by side, it only takes one failure to create a larger problem. Without secondary containment, that spill could spread quickly and reach places it shouldn’t.

Some facilities have additional requirements based on how they process chemicals, how much material is on site, or how the area is regulated. Containment plans should account for those details—not just the volume, but the layout and how the space is used.

How State-Level Rules Expand or Tighten Federal OSHA Standards

OSHA sets a nationwide baseline for chemical storage and handling, but some states run their own OSHA-approved workplace safety programs. A state program can go beyond federal requirements as long as it meets or exceeds OSHA’s core standards.

California is one of the best-known examples. Under Cal/OSHA, chemical storage rules include added labeling requirements, stricter standards for separating incompatible materials, and more detailed ventilation and fire-control expectations for flammable storage areas. Other states with their own programs—such as Washington, Oregon, and Michigan—also impose additional requirements in some areas. Local fire codes can add another layer.

Employers in a state with its own program are expected to follow both the federal baseline and any extra provisions that apply locally.

Training and Documentation Obligations for Anyone Handling Chemicals

When Training Is Required and What It Needs to Cover

Employers are responsible for making sure employees who work with hazardous chemicals know how to store, label, and handle them safely. OSHA expects that training takes place before an employee begins working with a chemical and whenever new hazards are introduced into the workplace.

Training should cover how to read container labels, how to use Safety Data Sheets (SDSs), and what steps to take in the event of a spill or exposure. Workers also need to understand the specific hazards tied to the chemicals they use—such as whether a product is flammable, corrosive, or reactive with other substances on site.

Written Program, SDS Access, and Emergency Response

OSHA requires employers to keep a written hazard communication program that includes a chemical inventory, labeling procedures, and a record of training activities. SDSs need to be accessible during every shift, and employees need to know exactly where to find them.

OSHA draws a clear line between minor spills that trained employees can handle and uncontrolled releases that require a specialized response. An incidental spill can be cleaned up by staff using routine procedures. A release that presents a significant safety or health hazard—such as a fire risk or exposure to toxic vapors—may trigger the requirements under HAZWOPER (29 CFR 1910.120), including emergency planning and advanced training.

What OSHA Will Look For During a Chemical Storage Inspection

During an inspection, OSHA focuses on how chemicals are stored, labeled, documented, and monitored. Inspectors evaluate both the physical setup and how well employees understand and follow safety requirements. Key areas of focus include:

Chemical inventory: Inspectors check for a complete and current list of all hazardous chemicals used or stored at the facility.
Labeling: All containers, including secondary ones, need to be clearly labeled with the chemical name and hazard information. Inspectors tend to spot violations tied to unlabeled spray bottles, unmarked jugs, or faded labels.
Safety Data Sheets (SDSs): SDSs are expected to be available to employees during every shift and need to match the products listed in the inventory.
Storage layout: Chemicals need to be stored in a way that prevents leaks, reactions, or physical damage. OSHA expects aisles to remain clear, exits to stay unobstructed, and incompatible substances to be separated. Containers shouldn’t be stacked in unstable ways or stored near ignition sources.
Flammable storage requirements: Cabinets and rooms used to store flammable liquids are expected to meet the standards under 29 CFR 1910.106. That can include fire-rated construction, mechanical ventilation, and features that contain spills.
Warning signs: Storage areas should have visible signage where appropriate—such as “Flammable – Keep Fire Away” or “No Smoking” signs posted on doors and cabinets.
Condition of containers: Inspectors check for leaks, corrosion, or signs of damage. Even a minor issue like a dented drum or rusted cap can draw attention.
Employee knowledge and training: Inspectors frequently ask employees where to find an SDS or how to respond to a spill. Inconsistent answers, or a lack of basic understanding, can lead to further scrutiny, even if the facility appears physically organized.

For a broader look at how OSHA enforces compliance across various workplace hazards, see Common OSHA Violations and How to Avoid Them.

When to Get Help with OSHA Compliance or Violations

OSHA citations tied to chemical storage can lead to costly penalties, shutdowns, and long-term liability. Employers who store hazardous materials should know exactly what standards apply and what inspectors will expect to see. If your storage setup hasn't been reviewed recently or if you've received a citation, legal guidance can make the difference between a fixable issue and a lasting problem.

Conn Maciel Carey LLP’s national, OSHA Workplace Safety Practice Group advises employers on chemical storage compliance, responds to OSHA inspections, and defends against enforcement actions. To speak with an attorney, contact our team directly by calling (202) 715-6244 or by sending us a note via our contact form.

This article is for informational purposes only and does not constitute legal advice. While we strive to ensure accuracy, laws and regulations may change, and unintended errors may occur. This content may not address every aspect of the relevant legal requirements. For guidance on your specific situation, consult your attorney.