ATL and EZ Flow: What is the difference

EZ flow

The EZ flow system is a “gravel-less” leach field / drain field option offered by Infiltrator Water Technologies. It replaces the traditional crushed-stone field with engineered geosynthetic “bundles” around perforated piping. Septic Shields+3infiltratorwater.com+3infiltratorwater.com+3
Key features:

• Pre-assembled units: typically a 3″ or 4″ perforated pipe surrounded by engineered media (synthetic aggregate) held together with netting. infiltratorwater.com+1

• Eliminates many issues associated with gravel-based systems (e.g., compaction of stone, settling of fines). Bethany Septic Supply+1

• Lightweight, easier to install in some conditions. infiltratorwater.com+1

• Can often reduce the required footprint: “health departments have approved sizing reductions of 25–50% when EZflow is specified.” Septic Shields+1

ATL (Advanced Treatment Leachfield)

ATL is another product from Infiltrator (or affiliated) described as a “passive advanced treatment leachfield” and sand-lined combined treatment/dispersal system. infiltratorwater.com+1
Key features:

• Effluent from septic tank passes into the ATL system, which comprises multiple layers: a 4″ diameter pipe, large-synthetic aggregate, fine geotextile, small synthetic aggregate, coarse geotextile, and a 6″ (or more) “system sand” layer. infiltratorwater.com+2Michigan+2

• It aims to produce a higher-level treated effluent (Class I as per NSF/ANSI standards) than a typical conventional leach field. infiltratorwater.com+1

• Designed for easier site suitability, shallower footprint, fewer sand fill requirements. Onsite Installer+1

How they differ (side-by-side)

Here are the main differences between EZ flow and ATL, particularly in typical septic / leach field applications:

FeatureEZ flowATLPrimary functionGravelless leach/dispersal field replacement for gravel & pipe systems.Combined treatment + dispersal system (i.e., more advanced than simple dispersal).Treatment levelStandard leach-field level (effluent from tank passively disperses).Higher level: Class I treatment (per some jurisdictions) before dispersal. Virginia Department of Health+1Media & configurationEngineered synthetic aggregate bundles surrounding perforated pipe; no stone & gravel bed required. infiltratorwater.com+1A layered system: pipe → synthetic aggregate → geotextile ⇒ system sand layer ⇒ native soil. Michigan+1Footprint / site‐fitCan reduce field size due to better flow/distribution; lighter install.Also designed for challenging sites (shallow soils, fill, slope) and reduced sand fill compared to older systems. Onsite InstallerInstallation complexity / costGenerally easier/faster: less excavation, less heavy stone hauling. Bethany Septic Supply+1More components, need the system sand and proper layering; may incur more cost depending on site.Ideal use-caseFor many typical homes wanting modern leach field, especially when space or excavation is constrained.For sites with stricter constraints (e.g., higher effluent quality needed, shallower soil, more demanding regulatory treatment requirements).Regulatory / code approval mattersWidely used and accepted for many jurisdictions (but always verify your local code).Specifically tested to meet NSF/ANSI 40 Class I in some cases; thereby may allow increased flexibility in difficult sites. Onsite Installer

Pros & Cons – What to weigh

EZ flow – Pros

• Faster install, less disruptive to property (less rock hauling, excavation).

• Lightweight bundles make transport & installation easier in tight areas.

• Good for renovation/repair of old fields where conventional gravel may be challenging.

• Potentially smaller system size (less area) which means less yard disruption.

EZ flow – Cons

• As with any system, results depend strongly on correct installation and soil/site conditions.

• Some contractors/users have reported concerns about long-term durability or performance (depending on site). For example:

  “currently have … EZflow. The 2nd system will probably add about 200LF … Gravel or EZflow? … ‘EZflow is garbage.’” Reddit

• May still require permitting and local health code compliance; not a “one-size fits all”.

• Less “advanced treatment” (i.e., not primarily designed to treated effluent beyond conventional levels) compared to a treatment field.

ATL – Pros

• Higher treatment capability before dispersal: can meet stricter effluent quality standards.

• Great choice when ground conditions are challenging: shallow soils, fill sites, slopes, etc.

• Designed to maximize site suitability and reduce sand fill/footprint compared to old rock & pipe systems.

• Might allow more flexibility in jurisdictions if you need the more advanced system.

ATL – Cons

• More complex installation: layering system sand, geotextile, aggregates etc.

• Potentially higher cost, more technically demanding to install correctly.

• Site still must meet minimum separations and other conditions (e.g., vertical separation from limiting layers) as noted in design manuals. Michigan

• Since it is a “combined treatment/dispersal” system, maintenance, inspection, or design may be slightly more involved.

Which one should you choose?

When deciding between EZ flow vs ATL, here are the key questions you should ask:

1. What are my site conditions?

   • Soil type, depth to limiting layers, water table, slope.

   • Do I have significant constraints (shallow soil, fill, compacted site) that might lean toward a more advanced solution (ATL)?

2. What are the regulatory or local code requirements?

   • Does local health department require a certain effluent quality or approve reduced footprint only with advanced systems?

   • For example, if code allows size reductions only for systems that meet certain treatment protocols, ATL might give advantage.

3. Budget & disruption tolerance

   • If you want to minimize cost, property disturbance, and timeline, EZ flow might be better.

   • If you’re willing to invest more up front for a system that handles tougher conditions or higher treatment needs, ATL may make sense.

4. Future maintenance & longevity

   • Ask about warranty, expected life span, how the system handles high loads (e.g., lots of laundry, large household) or changes in usage over time.

   • Verify installation contractor’s experience with each system.

5. Footprint & design flexibility

   • If the property is small or you have landscape features you want to preserve (trees, yard, existing landscaping), the lighter install of EZ flow might be attractive.

   • If site is awkward (steep slope, shallow soils, fill) then ATL’s design flexibility may win.

My take / recommendation

If I were advising someone in your situation (with a typical house, average soil but maybe some constraints) I’d lean toward EZ flow as the first choice unless the site has significant limitations (very shallow soil, high water table, regulatory requirement for advanced treatment, or you’re planning for high usage). Because the lighter cost and easier install make it compelling.

However, if the site is challenging (e.g., limited depth, fill material, steep grade, or you anticipate heavy usage) then spending the extra for ATL could save headaches down the road.

Always bring in a qualified onsite-wastewater system designer/installer who has experience with both systems in your area. Have them evaluate soil logs, local approval possibilities, and cost vs benefit.