Landfill Wastewater Effluent Guidelines

Landfills generate wastewater — primarily leachate, the contaminated liquid that percolates through buried waste — that must be collected and treated before discharge. 40 CFR Part 445 establishes the federal technology-based effluent limits for wastewater discharges from landfills, covering both hazardous waste landfills and municipal solid waste landfills in separate subparts.

Legal Authority

• 33 U.S.C. § 1311 — Clean Water Act § 301: prohibits discharge of pollutants from point sources unless authorized by NPDES permit with technology-based effluent limits; landfill leachate discharges are point sources subject to this requirement
• 40 CFR Part 445 — EPA effluent limitation guidelines for the landfill point source category; sets pollutant-specific limits for leachate and other wastewater from hazardous waste and non-hazardous solid waste landfills

Key Mechanics

Part 445 applies the Clean Water Act's standard technology-based framework (BPT, BAT, BCT, NSPS) to landfill wastewater. The primary regulated discharge is leachate — contaminated liquid that percolates through buried waste and collects at the landfill base. Facilities that discharge leachate directly to surface waters must meet the numeric limits in Part 445; facilities that discharge to a POTW must comply with pretreatment standards. The most common practice is indirect discharge: collecting leachate and hauling it to, or piping it to, a municipal wastewater treatment plant for treatment. Direct discharge is permitted only with a more stringent NPDES permit meeting Part 445's limits.

Current Rule (2026)

What This Rule Does

40 CFR Part 445 sets limits on the concentration of pollutants in wastewater discharged from landfill units to receiving waters. Landfill leachate typically contains metals, ammonia, BOD, dissolved solids, and trace organics from decomposing waste. The effluent limitations in Part 445 reflect best available technology for leachate treatment — biological treatment, precipitation and filtration, and reverse osmosis for the most contaminated streams.

For most landfills, the principal wastewater management path is pretreatment and discharge to a POTW (publicly owned treatment works — a municipal sewage system), not direct discharge to a navigable water body. In that case, the Pretreatment Standards for Existing Sources (PSES) and Pretreatment Standards for New Sources (PSNS) in Part 445 apply, not the direct discharge BPT/BAT limits. The choice of discharge path determines which standards govern.

Key Provisions

• § 445.1 — General applicability: covers wastewater from landfill units; excludes surface impoundments, underground injection wells, waste piles, and land application units used for wastewater management; excludes landfills receiving residential household waste exclusively, unless they accept industrial or commercial waste
• § 445.10 — Subpart A (Hazardous Waste Landfills): applies to landfills regulated under RCRA Subtitle C (40 CFR Parts 264 and 265); pollutants regulated include BOD5, TSS, ammonia (as N), alpha terpineol, benzoic acid, p-cresol, phenol, zinc, and other metals; zero discharge of process wastewater is the standard for hazardous landfills — leachate must be re-injected or treated to zero discharge
• § 445.11 — BPT limits for hazardous landfills: effluent limitations for best practicable technology, expressed as maximum daily and monthly average concentrations
• § 445.20 — Subpart B (MSW Landfills): applies to municipal solid waste landfills (those receiving residential garbage, commercial waste); regulated pollutants include BOD5, TSS, ammonia, arsenic, chromium, zinc, alpha terpineol, benzene, naphthalene, phenol; numeric limits expressed in mg/L; direct discharge is regulated by BPT, BAT, NSPS; discharge to POTW is regulated by PSES/PSNS
• § 445.21 — MSW BPT limits: primary limits reflecting basic biological treatment; ammonia limit of approximately 10 mg/L (monthly average); BOD5 limit of 210 mg/L
• § 445.22 — MSW BAT limits: tighter limits reflecting advanced treatment technologies; some pollutants regulated at lower concentrations; several specific organic compounds regulated at trace concentrations
• § 445.40 — Subpart C (Construction/Demolition Debris Landfills): generally less contaminated than MSW leachate; applies BPT/BAT standards for TSS, pH, and specific metals associated with construction materials (lead, cadmium, chromium)

How It Affects You

Landfill owners and operators — if your landfill directly discharges leachate to a water body, you need an NPDES permit incorporating Part 445 effluent limits. More commonly, landfills discharge leachate to the municipal sewer system; in that case, you need an industrial pretreatment permit from the local POTW, incorporating the PSES limits from Part 445.

Municipal wastewater systems — receiving landfill leachate must ensure it doesn't cause pass-through or interference with the POTW's own NPDES permit; pretreatment limits from Part 445 protect POTW operations and downstream water quality.

Hazardous waste landfill operators face the most stringent standards — zero discharge for hazardous constituents is the norm; leachate is collected, stored, and typically re-circulated or sent to a permitted hazardous waste treatment facility.

Statutory Authority

This rule implements:

• 33 U.S.C. § 1311 — CWA § 301: technology-based effluent limitations for point source categories; new source performance standards; pretreatment standards for industrial users discharging to POTWs

Recent Rulemakings

• 65 FR 3008 (Jan. 19, 2000) — original final landfills ELG rule establishing the BPT/BAT framework (40 CFR Part 445)
• EPA has considered updates to the landfill ELG, particularly for emerging contaminants (PFAS) in leachate from MSW landfills; as of 2026, a proposed update to address PFAS in landfill leachate is under development

Pending Action

{Leave empty — the wiki-enrich skill will fill from federal_register table.}