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How We Verify Septic Licenses

Every license badge on The Septic Guide comes from a state agency's own published list. Here is exactly how it works.

Last updated

The Septic Guide marks a listing as licensed only when the business or person appears on a septic license or certification list published by the state agency that issues it. As of October 2026, 27,059 of the 28,538 listings in The Septic Guide are matched to one of these lists.

1. We start from the state's own list

For each state that publishes its septic license holders, we download the agency's list: a spreadsheet, a PDF roster, an open-data file or a public search. We keep only active, unexpired credentials, and only holders based in that state.

2. We match license holders to businesses

Many states license the individual installer rather than the company. We group licensed people with the business they work for when the list itself ties them together (a shared company name, phone number, email domain or street address), and we match businesses to their public business listing by phone number or by a name and town match. When a list gives only a person's name, the listing keeps the person's name until we can confirm the business.

3. We show what was matched, and where

A license badge shows the credential type, the license number when the state publishes one, and the issuing agency, with a link to that agency's lookup so you can confirm it yourself. Services marked per state license follow from the license type; services marked from their website were found on the business's own website.

4. What a badge does not mean

A license badge is not a review of the contractor's work, and a license can lapse after our last update. Always confirm the license with the agency and ask for proof of insurance before you hire. Listings without a badge are not unlicensed: their state may not license septic work, or we have not matched them yet.

5. How often it is updated

We reload a state's list when the agency publishes a new one, and review every state at least quarterly. The date on each page shows when its data was last refreshed.

State lists we use

  • Arizona: ROC posting list, class CR-41 (Arizona Registrar of Contractors)
  • Arkansas: ADH onsite wastewater licensee list (Arkansas Department of Health, Onsite Wastewater)
  • California: CSLB license data, classification C-42 (Contractors State License Board (CSLB))
  • Connecticut: Connecticut State Licenses and Credentials open data (Connecticut Department of Public Health (licensing through the state eLicense system))
  • Delaware: DNREC Class E contractor roster (Delaware open data) (Delaware DNREC)
  • Georgia: DPH certified installers list (Georgia Department of Public Health, Environmental Health)
  • Idaho: Public health district permitted installer and pumper lists (Idaho's seven public health districts, under Idaho DEQ rules)
  • Illinois: IDPH private sewage license search (Illinois Department of Public Health, Private Sewage Disposal Program)
  • Louisiana: LDH active installer list (Louisiana Department of Health, Onsite Wastewater Program)
  • Maryland: MDE BAT certified installer list (Maryland Department of the Environment)
  • Michigan: EGLE septage hauler directory (Michigan EGLE Septage Waste Program (pumpers); county health departments (installers))
  • Minnesota: MPCA SSTS licensed business search (Minnesota Pollution Control Agency (SSTS program))
  • Mississippi: MSDH certificate holder search (Mississippi State Department of Health, On-Site Wastewater)
  • Nebraska: NDEE certified onsite wastewater professionals list (Nebraska Department of Water, Energy, and Environment (Title 124))
  • New Hampshire: NHDES permitted septic designer and installer list (October 2026) (NH Department of Environmental Services, Subsurface Systems Bureau)
  • North Carolina: NCOWCICB certification list (NC Onsite Wastewater Contractors & Inspectors Certification Board)
  • North Dakota: ND annual active licensed installer list and local health unit lists (North Dakota DEQ and local public health units)
  • Oklahoma: DEQ active certified installers list (Oklahoma DEQ, Environmental Complaints and Local Services)
  • Oregon: DEQ certified onsite installer list (Oregon DEQ, Sewage Disposal Service licensing)
  • Rhode Island: DEM licensed OWTS installer list (July 2022) (Rhode Island DEM, OWTS program)
  • South Carolina: SCDES septic contractor map data (South Carolina Department of Environmental Services)
  • South Dakota: Plumbing Commission small wastewater installer roster (South Dakota State Plumbing Commission)
  • Tennessee: TDEC permitted active installers list (Tennessee Department of Environment and Conservation, Division of Water Resources)
  • Texas: TCEQ authorized contact list (OSSF) (Texas Commission on Environmental Quality (TCEQ))
  • Virginia: DPOR regulant lists (Virginia DPOR, Board for Waterworks and Wastewater Works Operators and Onsite Sewage System Professionals)
  • West Virginia: OEHS certified septic installer list (West Virginia Office of Environmental Health Services)

Pennsylvania listings come from the Pennsylvania Septage Management Association member directory, which is an association membership, not a state license. Some state lists carry legal limits on solicitation (Idaho Code 9-348, S.C. Code 30-2-50); we use them only to list providers, never to contact them.