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Advanced Treatment Systems in Rankin County

Four tanks doing the job that one tank plus good soil would have done for free.

That is the honest way to read what follows. A powered treatment system is not a better system in some abstract sense. It is the system you buy when the ground will not treat the water for you, and it earns its cost by producing effluent clean enough to be released into far less soil than a conventional field would need.

On a lot with shallow Yazoo clay the conventional trench is usually off the table before the conversation starts, and no amount of extra trench length fixes ground that will not accept water. What the evaluator is measuring is how much usable soil sits above the clay, because that margin is the entire design. Where it is thin the system comes up out of the ground as a mound, or the water is treated mechanically before it is released. Both cost more than a trench, and on this ground both are frequently the only lawful options.

Cutaway of an aerobic treatment unit Four stages left to right: a trash tank where solids settle, an aeration chamber where a compressor injects air and bubbles rise through the liquid, a clarifier where the remaining solids settle out and return, and a pump tank with a chlorinator that feeds spray heads distributing disinfected effluent across the lawn. Aerobic treatment unit (ATU), section view COMPRESSOR RUNS 24/7. IT IS ON YOUR POWER BILL. CHLORINATOR TABLETS, TOPPED UP BY YOU GRADE FROM HOUSE 1 · TRASH TANK SOLIDS SETTLE 2 · AERATION AIR IN, BACTERIA WORK 3 · CLARIFIER SOLIDS GO BACK 4 · PUMP TANK FLOAT SWITCH SPRAY DISTRIBUTION DISINFECTED EFFLUENT, ONTO YOUR LAWN SEASONAL HIGH WATER TABLE
Left to right: solids settle out in the trash tank, a compressor feeds air to the bacteria doing the actual treating, the clarifier sends the last of the solids back for another pass, and a float switch pumps the finished effluent out to the spray heads through a chlorinator you keep topped up. Four tanks doing what one tank plus good soil would have done for free. That is the honest way to read this drawing: an ATU is not a better system, it is the system you buy when the ground will not treat the water for you. It also means a compressor on your power bill and a maintenance obligation you are required to keep.

Treatment units in Rankin County: when they are required, and who services them

USDA soil survey data rate about 448,000 acres of Rankin County “very limited” for septic absorption fields and only about 5,900 acres anything better. Slow water movement (about 406,000 acres) and a near-surface saturated zone (about 368,000) are the most widespread reasons. Kipling soils, about 44,000 acres, are rated very high for shrink-swell.

Where a Rankin County evaluation ends in an advanced treatment unit, it comes with the maintenance affidavit and, under contract, two inspections a year.

In Mississippi the work that brings an advanced unit back into compliance, such as replacing spray heads, aerators or pumps and chlorine tablets, is done by a Certified Installer. MSDH no longer certifies new maintenance providers: the providers are those certified on 26 April 2011 or Certified Installers.

County office: Rankin County Health Department, 401 Parkway Drive, Pearl, MS, 601-420-4959; Rankin is in MSDH’s Central environmental region.

Sources: USDA-NRCS Soil Data Access (SSURGO), septic tank absorption field ratings, queried 2026-10-23; MSDH, Affidavit (Maintenance) for an advanced treatment system (form 7437); MSDH, Title 15 Part 3 Subpart 77, Individual On-Site Wastewater Disposal Systems; MSDH: county health departments, Central region. Checked October 2026.

What owning one is actually like

  1. Something is always running

    The compressor runs continuously. It is on your power bill, it makes a noise, and when it stops the system stops treating: quietly, and without telling you, until the alarm goes.

  2. There are consumables

    Disinfection tablets get used up. A system that has run out is a system discharging undisinfected effluent onto the lawn, which is both the thing the design exists to prevent and a compliance problem.

  3. There is a service schedule, and it is not advisory

    Mississippi requires every system to be maintained to the certified manufacturer requirements under Miss. Code Ann. §41-67-10, and advanced treatment systems additionally under §41-67-7(5).

  4. It shows up when you sell

    A buyer's lender and inspector will ask about it, and the answers are on file with the authority. See inspections.

The paperwork is part of the system

An advanced treatment system has moving parts and a disinfection stage, and the state treats it as something that has to keep being looked after rather than something signed off once. On shrink-swell ground there is a second reason to keep the visits up: tanks and lines move with the clay, and joints that were sound at install do not always stay sound.

Is it worth it?

It is not a choice on most lots that need one. If the soil report rules out a conventional field, the alternatives are a powered system, an engineered alternative like a mound, or not building. Where there is a genuine choice, the trade is a lower install cost and no running cost against a higher install cost and a permanent service obligation, and the right answer depends on how long you plan to own the place.

Need to know which your lot can take?

A licensed site evaluator has to answer that with a soil test; nobody can tell from a map. Send us your address and we will pass it to a licensed local professional where one is available. Request a quote →

Last reviewed September 28, 2026 against the Mississippi State Department of Health and the Mississippi State Department of Health published rules. How we research this site.