McHenry County Department of Health - Environmental Health
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Septic System FAQ's

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Q: Do I need a permit to repair my septic system?
A: A permit [PDF] is required from the McHenry County Department of Health to install, modify, alter, extend, repair, replace or abandon a septic system in McHenry County. Permit application must be submitted in person or by mail.

Q: How do I apply for a septic system permit?
A: Permit applications may be submitted by mail or in person at the Environmental Health Division of the McHenry County Department of Health. The materials required to be submitted with the permit application vary depending upon the type of permit requested. See Educational Materials: So You Are Applying For A Septic Permit [PDF]

Q: How do I get a copy of the plans for my existing septic system?
A: Records of septic systems permitted prior to February 1, 2003 are located at the McHenry County Department of Planning & Development.

Records of septic systems permitted on or after February 1, 2003 are located at the Environmental Division of the McHenry County Department of Health. A Freedom of Information Act Request Form must be submitted to obtain copies of public records. A nominal fee is required for printing costs.

Q: Can I install or repair my own septic system?
A: All septic system installations, repairs or modifications in McHenry County must be done by Illinois Department of Public Health Licensed Septic System Installation Contractors.

Q: How can I find out if a vacant lot is buildable?
A: Whether a lot is buildable depends on a variety of factors including zoning restrictions, building requirements, storm water control requirements and the ability to provide for a potable water supply and wastewater treatment and disposal. Recently platted subdivisions have been evaluated for these issues.

A site evaluation can be completed to determine if a permit can be issued to install a septic system to serve a new residence or structure. This requires a soil boring report completed by a certified soil classifier. Additional information may also be required to evaluate the impact of flood plain and setback distances from structures, existing water wells and septic systems particularly on small lots or parcels.

Q: Can I add a bedroom to my house which is served by an onsite wastewater treatment system?
A: The addition of a bedroom requires that the onsite wastewater treatment system meet new construction standards for the total number of proposed bedrooms. A qualified septic system designer can help you determine whether the system does or can be modified to meet those standards.

Q: Are Aerobic Treatment Units allowed in McHenry County?
A: Aerobic Treatment Units accepted by the Illinois Department of Public Health are allowed for use in McHenry County provided that they discharge into a compliant subsurface seepage system. Surface discharging onsite wastewater treatment systems are not allowed in McHenry County.

Q: Are holding tanks permitted in McHenry County?
A: Holding tanks are only allowed in very limited circumstances:

  • As a temporary measure (less than 180 days) while awaiting connection to community sewer; or
  • As a temporary measure (less than 6 months) while awaiting installation of a permitted septic system delayed due to weather conditions; or
  • As a sanitary dumping station in campgrounds or marinas to receive wastewater from recreational vehicles or boats; or
  • As a special waste holding tank to receive discharges from drains or fixtures receiving any wastewater other than domestic sewage.

Q: Should I put enzymes or additives into my onsite wastewater treatment system to help it work better?
A: The McHenry County Department of Health does not recommend the use of septic tank additives. No third party, independent study has confirmed that there is any benefit to septic tank additives. Additionally some additives may negatively impact groundwater quality.

Q: What can I do if I think my neighbor’s septic system is malfunctioning and my neighbor is not correcting it?
A: Contact the McHenry County Department of Health. Complaints can be taken anonymously. Department staff will investigate whether the system is malfunctioning. If the system is found to be in failure, staff will work closely with the property owner to ensure that the appropriate corrective action is taken.

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