A reliance letter in an environmental site assessment is a document issued by the environmental consultant that lets someone other than the original client legally depend on the findings of a Phase I ESA (or Phase II) and hold the consultant accountable if the work was deficient. Without one, only the party who hired the consultant has that standing. These letters come up constantly in commercial real estate because lenders, buyers, and investors often need to use an ESA they didn’t commission.
Why You Can’t Just Read Someone Else’s ESA
Contract law generally limits enforcement of a contract to the people who signed it. Under this principle, known as privity of contract, if a seller hires an environmental consultant to prepare a Phase I ESA, only that seller can take legal action if the report was negligently prepared.1Legal Information Institute. Privity Everyone else who reads the report is, legally speaking, a stranger to the contract.
Courts have enforced that boundary. In one case, a borrower was blocked from suing an environmental consultant whose reports were prepared for the lender, because no contractual relationship existed between the consultant and borrower when the reports were created. The court held that any intent to protect the borrower was “at best secondary” to the lender’s due diligence needs.
A reliance letter formally extends the consultant’s duty of care to named third parties before a problem surfaces. The consultant accepts additional liability exposure in exchange, which is why these letters aren’t handed out automatically and why there’s typically a fee.
Why It Matters for CERCLA Liability
The bigger reason reliance letters matter is federal environmental liability law. Under the Comprehensive Environmental Response, Compensation, and Liability Act, anyone who owns contaminated property can be held financially responsible for cleanup costs, regardless of whether they caused the contamination. CERCLA provides several defenses against that strict liability, but each requires the buyer to have conducted “all appropriate inquiries” into the property’s environmental history before acquiring it.2Office of the Law Revision Counsel. 42 USC 9601 – Definitions
A Phase I ESA conducted under the ASTM E1527-21 standard is the accepted way to satisfy that inquiry requirement. But the party claiming the defense must qualify as a “user” of the ESA. When a subsequent party wants to rely on an ESA originally prepared for someone else, the reliance letter is the contractual mechanism that bridges the gap, giving the new party both legal standing against the consultant and a documented chain supporting their CERCLA defense.
The bona fide prospective purchaser defense, for example, shields a buyer from cleanup liability provided they conducted all appropriate inquiries before acquisition and don’t interfere with any ongoing cleanup.3Office of the Law Revision Counsel. 42 USC 9607 – Liability If a buyer relies on an ESA addressed only to the seller and later discovers contamination, the lack of a reliance letter could undermine that defense entirely.
Who Typically Needs One
Lenders request reliance letters more than anyone else. Major secondary market institutions like Fannie Mae explicitly require that a Phase I ESA be addressed to and authorize reliance by the lender, the institution itself, and their successors and assigns.4Fannie Mae. Environmental Due Diligence Requirements If a borrower commissions an ESA that doesn’t name the lender as an authorized relying party, the lender will either demand a reliance letter or require an entirely new assessment, which costs more and delays closing.
Buyers who weren’t the original client are in a similar position. A seller may have a recent Phase I ESA in hand, and the buyer would prefer to use it rather than pay for a new one. A reliance letter makes that possible and preserves the buyer’s CERCLA protection.
Investors, joint venture partners, and tenants with meaningful environmental exposure also benefit. Any party whose financial decisions depend on the accuracy of an ESA should either be named as the original client or obtain a reliance letter.
What the Letter Contains
Reliance letters are short but carefully structured. A typical letter identifies the ESA by project name, date, and property address so there’s no ambiguity about which report is covered. It names each party being granted reliance and states that those parties may depend on the findings as though they had been the original client.
The letter also defines the limits of that reliance. It confines the scope to the report’s original findings and the conditions that existed at the time of the assessment. The consultant doesn’t take on open-ended liability for anything that happens after the report date or for conditions outside the assessment’s scope.
Disclaimers and liability caps are standard. Consultants often tie the reliance letter to the terms of the original engagement agreement, including any limitations on damages. Sophisticated parties frequently negotiate specific language around insurance requirements or liability thresholds, and the consultant decides whether their report can meet those additional terms.5RSB Environmental. Environmental Reliance Letters: Guide and Template
Timing and the 180-Day Shelf Life
A reliance letter does not extend the useful life of an ESA report. Under ASTM E1527-21, a Phase I ESA is considered viable for 180 days from the dates its key components were completed. That window can stretch to one year if certain elements are updated, including interviews, government records review, site reconnaissance, and the environmental professional’s declaration. The 2021 update calculates those periods from individual component completion dates rather than the final report date, which effectively shortens the report’s shelf life compared with earlier versions of the standard.
Request a reliance letter while the underlying ESA is still fresh. If the 180-day window has closed, a reliance letter won’t revive it. You’ll likely need an updated assessment or a new Phase I, and at that point the cost savings disappear.
How Much It Costs
A reliance letter for a Phase I ESA typically runs between $250 and $600. When both Phase I and Phase II ESAs are involved, the cost rises to roughly $850 to $2,000. Most consultants charge between 10% and 20% of the original assessment’s cost to prepare the letter. A new Phase I ESA, by comparison, can cost several thousand dollars depending on the property’s complexity and location. The math almost always favors the reliance letter when one is available and the underlying report is still within its shelf life.
What a Reliance Letter Will Not Do
A reliance letter gives you legal standing and supports your liability defense, but it does not make the consultant your insurer. If the report was competently prepared and contamination simply wasn’t detectable through the standard Phase I process, the letter won’t help you recover cleanup costs from the consultant. A claim against the consultant requires showing that the work itself was negligent or fell below applicable professional standards.
The letter also doesn’t expand the scope of what was originally assessed. If the Phase I didn’t include sampling, soil testing, or investigation of a specific area, the reliance letter doesn’t retroactively add those services. You’re relying on exactly what was done. Environmental conditions can also change between the assessment date and your acquisition date, and the letter doesn’t cover that gap.
A reliance letter also does not transfer liability for actual contamination. If the property turns out to be contaminated, the responsible parties under CERCLA are still the current and former owners, operators, and parties who arranged for disposal of hazardous substances.3Office of the Law Revision Counsel. 42 USC 9607 – Liability The reliance letter helps you qualify for a defense against that liability and gives you recourse against the consultant if their work was deficient. Those are two separate protections solving two separate problems.