NSF/ANSI 40 — The Standard to Ask About
If you do need an ATU, verify the recommended model holds NSF/ANSI Standard 40 Class I certification — meaning effluent CBOD5 ≤25 mg/L and TSS ≤30 mg/L (30-day averages). If your site is near a water-supply watershed, also ask whether NSF/ANSI 245 (nitrogen reduction) is required. Both certifications are searchable on the NSF website.

Decision logic based on: Florida DEP requirements for ATU use cases (county ordinance, drainfield reduction in limited soils, drip irrigation, proximity to water); LSU AgCenter ATU guidance; Santa Cruz County enhanced treatment regulations; NSF/ANSI Standard 40 Class I performance criteria. Local rules govern all system selection decisions — verify with your county health department before committing to any system type.

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