Do I Have an I/A Septic System? How to Tell in Massachusetts (Plymouth County, Cape Cod & Beyond)
If you own a home in Southeastern Massachusetts, there’s a very real chance you have an I/A septic system—and don’t even know it.
We see this all the time across:
Plymouth County
Bristol County
Barnstable County (Cape Cod)
Homeowners assume they have a “regular septic system”…
👉 but they’re actually responsible for a regulated, advanced treatment system.
And that comes with requirements.
What Is an I/A Septic System (Quick Answer)?
An Innovative/Alternative (I/A) septic system is an advanced wastewater system designed to:
Reduce nitrogen
Improve treatment performance
Meet stricter environmental regulations
These systems are commonly required in:
Nitrogen-sensitive areas
Zone II aquifer protection zones
Coastal and environmentally sensitive regions
Why You Might Have One (Even If You Didn’t Install It)
Here’s the reality:
👉 Many I/A systems were installed as part of:
New construction
Septic system replacements
Property upgrades
So if you:
Bought your home in the last 10–20 years
Live on Cape Cod
Are near a public water supply (Zone II)
Had a system replaced
👉 You might already have one.
5 Signs You Have an I/A Septic System
1. You Have a Service Contract (or Were Told You Need One)
This is the biggest giveaway.
👉 I/A systems require ongoing service and reporting.
If someone told you:
“You need annual maintenance”
“This system needs to be monitored”
You likely have an I/A system.
2. There Are Mechanical Components or Controls
Look for:
Electrical panels
Timers or control boxes
Pumps or blowers
Standard septic systems don’t have these.
👉 Systems like Orenco or FAST almost always include mechanical components.
3. You Have Filters That Need Cleaning
If your system includes:
Effluent filters
Textile media (Orenco AdvanTex)
Specialized treatment units
👉 That’s not a basic system.
4. Your Property Is in a Nitrogen-Sensitive or Zone II Area
Common in:
Cape Cod (Barnstable County)
Marshfield, Plymouth, Kingston
Bridgewater, Middleboro, Raynham
👉 These areas often require I/A systems for compliance.
5. You’ve Heard Names Like “Presby,” “Orenco,” or “FAST”
If any of these sound familiar:
Presby (Enviro-Septic)
Orenco (AdvanTex)
FAST systems
BioClere
👉 You have an I/A system.
Why This Matters (Most People Get This Wrong)
Here’s the part that gets people in trouble:
👉 I/A systems are regulated—and require ongoing maintenance.
This typically includes:
Scheduled inspections
System monitoring
Maintenance of components
Reporting to your local Board of Health
If you’re not doing this:
You may be out of compliance
You could face enforcement or fines
Your system may fail prematurely
The Biggest Mistake Homeowners Make
We see this constantly in Plymouth County and Cape Cod:
Homeowner has an advanced system
Treats it like a standard septic tank
Only calls for pumping
👉 That’s not enough.
Pumping does not:
Maintain system performance
Ensure compliance
Protect mechanical components
How to Confirm What System You Have
If you’re unsure, here’s what to do:
1. Check Your Property Records
Your septic design plan (as-built) will list the system type.
2. Contact Your Local Board of Health
They often have records of:
System type
Installation
Maintenance requirements
3. Schedule a Professional Inspection
This is the fastest and most reliable way to know:
What system you have
What condition it’s in
What’s required to maintain it
Why This Is Especially Important in Southeastern MA
This region has:
Strict environmental regulations
High groundwater sensitivity
A growing number of I/A systems
Especially in:
Cape Cod
Coastal Plymouth County
Zone II aquifer areas inland
👉 These systems are only effective if they’re properly managed.
The Bottom Line
If you’re not sure what type of septic system you have:
👉 That’s a problem.
Because if it’s an I/A system:
👉 You have legal and maintenance responsibilities that can’t be ignored.
Onsite Wastewater Inspections LLC – Get Clear Answers
At Onsite Wastewater Inspections LLC, we help homeowners across Southeastern Massachusetts:
Identify their septic system type
Evaluate system condition
Understand maintenance requirements
Stay compliant with local regulations
We serve:
Bridgewater, Raynham, Middleboro, Berkley, Hanson, Halifax, Pembroke, Hanover, Kingston, Marshfield, Norwell, Plymouth, and Cape Cod.
👉 If you’re unsure what system you have—or what it requires—schedule an inspection and get real answers.
