What Is a Phase I Environmental Site Assessment?

The concern is simple. EPA explains that under CERCLA, the federal Superfund law, persons may be held strictly liable for cleaning up hazardous substances at properties they currently own or operate, and that liability may be assigned based solely on property ownership. You may never have used a chemical in your life and still have a problem if a past occupant did.

Congress created liability protections for certain buyers who did not cause or contribute to contamination. One requirement, EPA says, is conducting All Appropriate Inquiries (AAI) into a property's present and past uses before acquisition. The AAI standard applies to commercial buyers who may later seek that protection.

A Phase I is a common way to do that work. EPA states that ASTM International Standard E1527-21 is consistent with the AAI rule and can be used to satisfy it. Ask your environmental professional to state in the report which standard was followed.

EPA lists the activities that the AAI rule requires. Many must be done by, or under the supervision of, an environmental professional.

• Interviews with current and past owners, operators and occupants.
• A review of historical sources of information about the site.
• A review of federal, state, tribal and local government records.
• A visual inspection of the property and adjoining properties.
• An assessment of how obvious any contamination would be, and identification of significant data gaps.
• A written report signed by the environmental professional, including an opinion on whether conditions indicate a release or threatened release.

Some of the inquiry also falls on you, the buyer. EPA lists searches for environmental cleanup liens, any specialized knowledge you have about the property, and how the purchase price compares with the fair market value of the property if it were not contaminated. Expect a questionnaire, and answer it carefully.

A Phase I is largely research and observation. It should not be read as a clean bill of health.

EPA treats several items as potential additional services beyond the scope of the final rule, which can be added by agreement. Its list includes lead-based paint, mold, radon, asbestos, indoor air quality, regulatory compliance and Phase II sampling and analysis.

That matters to owner-users because some of those items may affect your build-out and your employees, even if they do not affect Superfund liability. An older building you plan to renovate is a clear example. Ask your consultant what else to add for your specific building and use.

Read the data gaps section as closely as the conclusion. A report can only speak to what the consultant was able to see and find.

The dates deserve close attention. Under 40 CFR 312.20, as read in November 2026, all appropriate inquiries must be conducted within one year before the date of acquisition. In addition, certain components must be conducted or updated within 180 days before acquisition:

• Interviews with past and present owners, operators and occupants.
• Searches for recorded environmental cleanup liens.
• Reviews of government records.
• Visual inspections of the facility and adjoining properties.
• The environmental professional's declaration.

So a report that looked fine at the start of a long deal can go stale if the closing slips. You can use an earlier report, including one prepared for someone else, only if the rule's conditions are met, which include reviewing it and updating it as required. Do not assume the seller's old Phase I covers you.

1. Order it early enough to read the findings before your due diligence deadline, and late enough to stay within the 180-day window if closing is far away.
2. Check your consultant's qualifications. EPA describes the education, license and experience paths that make someone an environmental professional.
3. Tell your lender before you order. Lenders may have their own requirements for who is named and who may rely on the report.
4. Give the consultant access to the site, past reports and anyone who knows the property's history.
5. Read the opinion, findings and data gaps, ideally with your attorney.
6. If the report recommends more investigation, price it and decide whether you need more time under the contract.

If you use an SBA loan, a separate set of rules applies to your lender. SOP 50 10 8.1 (effective October 1, 2026, and subject to change) requires an environmental investigation of commercial property taken as collateral. The starting point depends on the property's uses and the loan amount: a current or known prior use on SBA's list of environmentally sensitive industries requires starting with a Phase I, regardless of loan amount. Phase I and Phase II reports must be performed by an environmental professional and come with a reliance letter. Ask your lender or CDC what your deal requires.

A finding is not automatically the end of the deal. Your options depend on what was found, and your contract's terms: more investigation, a price adjustment, seller cleanup, specific protections in the contract, or termination.

EPA's bona fide prospective purchaser provision may allow a party to acquire a property knowing or having reason to know of contamination, if it meets the statutory criteria. That protection is not free. The buyer must meet continuing obligations after closing, including taking reasonable steps to stop continuing releases and prevent threatened future ones. Your environmental attorney should explain what you would be taking on before you decide.

Tenant Advisory Group is not an environmental consultant or a law firm. On a purchase, we help buyers build the Phase I into the contract timeline, so the findings arrive while they can still affect the negotiation.