The hazardous substances clause controls which chemicals, fuels and regulated materials you can bring onto an industrial property, what you must disclose, and who pays to investigate and clean up contamination. It also contains indemnities, the promises each side makes to cover the other's losses, and those promises usually keep running after the lease ends.
What this clause does
Industrial operations use more regulated materials than most executives realize. Propane for forklifts, lead acid and lithium batteries on charging stations, hydraulic fluid, lubricants, solvents, paint, adhesives and diesel for yard equipment can all qualify. Most standard Southern California industrial lease forms define hazardous substances broadly, covering nearly anything a government agency regulates or anything that could expose the owner to liability.
The clause usually does four jobs. It requires the landlord's consent before you bring in more than ordinary quantities used in normal operations. It requires you to disclose what you use and to tell the landlord promptly if you learn of a release, including one you did not cause. It assigns responsibility for investigation and cleanup. And it sets indemnities, where one party agrees to defend and pay for the other's losses tied to contamination.
The landlord's worry is straightforward. Cleanup on an industrial site can cost more than years of rent, and regulators can look to the property owner no matter who caused the problem. Your worry should be just as simple: you want to be responsible only for the materials you bring onto the property, handled and disposed of properly, and nothing that was there before you or that drifted in from next door.
Set a baseline before you sign
Environmental disputes usually come down to one question: when did this condition start? The party that can prove the answer is in a much better position. So start by asking the landlord directly about the property's history and for any environmental reports in its files. Then verify it yourself. In California, the state water board's public database (GeoTracker) lets you search an address for known cases, cleanup history and regulatory activity.
For larger buildings, longer terms, sites with a manufacturing past, or any deal where your own operation will handle regulated materials, consider a Phase I environmental site assessment before you commit, followed by a Phase II with soil or vapor sampling if the Phase I raises flags. The goal is a documented line between the property's condition before you took possession and after.
Pay attention to vapor intrusion. When solvents are spilled on a slab over the years, they can migrate into the soil below and return as vapor inside the building. If testing shows elevated levels, the fix can involve mitigation systems and added air handling. You want to know that before your team works there every day, not after.
Where it goes wrong
Pre-existing conditions are a frequent trap. If the lease is vague about contamination that predates you, you may end up trying to prove a negative years later. Ask for language that plainly excludes conditions existing before your possession date and contamination migrating from neighboring properties, unless you caused or worsened it.
Indemnities are often one-sided. The tenant's promise to cover the landlord is typically broad and survives the lease, while many landlords decline to give any indemnity back, even for pre-existing materials. If you cannot get a mutual indemnity, push for a clear statement that the landlord remains responsible, at its cost, for remediating conditions it or prior occupants created.
Consent can also become a bottleneck. If your lease does not anticipate the materials in your process, adding a new line mid-term may require approval, and the landlord may condition that approval on a larger deposit, added insurance or monitoring. Some forms also give the landlord an exit if cleaning up a condition you did not cause would be too costly, so understand what that means for your operation and whether you can keep the lease alive.
Plan the exit on day one
At move-out you will generally need to remove everything you brought in and leave the property free of contamination you caused. Some landlords also require you to close out hazardous materials permits with the fire authority and provide proof. Keep your permits, material inventories, safety data sheets and disposal manifests organized from the start. A clean record is how you get your deposit back and close the door on future claims. Have an environmental consultant and a real estate attorney review the property and the actual lease language before you sign.
If you are the tenant
- Ask the landlord in writing for all environmental reports it has, and search the address on your state's water board database before signing.
- On larger or longer deals, commission a Phase I (and a Phase II if warranted) and reference the results in the lease as the baseline condition.
- Get lease language that excludes pre-existing contamination and contamination migrating from neighbors that you did not cause.
- List the materials your operation uses, such as forklift propane, batteries, lubricants and cleaning chemicals, in a lease exhibit so routine use is approved up front.
- Keep permits, inventories, safety data sheets and disposal manifests organized throughout the term; you will need them at move-out.
If you are the owner
- Document the property's condition at delivery. Without a baseline you cannot show that anything changed during the tenancy.
- Require a hazardous materials disclosure before lease signing covering chemicals, quantities, locations and storage practices, and update it when the tenant's use changes.
- Match the security deposit, insurance requirements and inspection schedule to the chemical risk of the tenant's use.
- If you agree to indemnify the tenant, limit it to conditions you or prior occupants created, not areas the tenant controls.
Go deeper in Justin's books
Both books walk through leases chapter by chapter, from the tenant side and the owner side.
You do not want to be subject to unhealthy conditions, and you do not want to be held liable for your landlord’s past environmental contamination.
Common questions
Am I responsible for contamination left by a previous tenant?
You should not be, but the lease has to say so clearly. Ask for language excluding conditions that existed before your possession date and supporting it with a baseline assessment. Without both, you may carry the burden of proving the problem predates you. Have a real estate attorney review the final wording.
Do I need a Phase I environmental report to lease a warehouse?
It depends on the deal. For a short lease of clean distribution space, direct questions to the landlord and a public database search may be enough. For longer terms, larger buildings, former manufacturing sites, or operations that will handle regulated materials, a Phase I is modest insurance against a very large liability.
Does forklift propane count as a hazardous substance under a lease?
Often yes, because lease definitions are broad. Most leases allow ordinary quantities used in normal business operations, but it is better to list propane, battery charging and similar routine materials in the lease so there is no argument later.
General information about how industrial leases commonly work, not legal advice. Every lease is different: have a California real estate attorney review yours before you sign.