Installer of Onsite Wastewater
Treatment Systems (CIOWTS) Credential
Find a Credentialed Installer in Your Area (PDF)
Exam and Application
Exam Description and Content Outline
75 questions on the basic level exam, and 125 questions on the advanced
level exam. All questions are written in multiple choice format. You
will have 2 hours to complete the basic level exam and 3 hours to
complete the advanced level exam. The CIOWTS exam is based upon the
following content areas. Next to each subject area the approximate
percentage of questions in that content area on the exam. The content
areas and approximate percentages of exam questions are the same for
both the basic level and the advanced level. The advanced level exam
includes more questions and questions of greater difficulty.
Knowledge of site plans; basic
surveying; topography; site features
Knowledge of materials requirements;
standards and specifications; soil profile descriptions; pump
performance; treatment and dispersal technologies
Ability to conceptualize an installation
Ability to make mathematical
calculations of area, volume, elevation, rates, measures and weights
JOB STAGING 20%
Knowledge of installation plans;
Ability to transfer designerís plan to
site; reconcile variations; identify conflicts
Knowledge of equipment needs and
limitations; materials and supplies; soil characteristics
Ability to make mathematical
Ability to identify subcontractor and
homeowner needs and potential conflicts
SITE DEVELOPMENT/ INSTALLATION 70%
Knowledge of soil characteristics;
ability to recognize soil characteristics in the field
Knowledge of specifications and
installation techniques for tanks, baffles, filters and screens,
piping and fittings, aggregate and fill material, proprietary
treatment components, pumps and siphons, liner materials, valves,
switches and tubing
Knowledge of electrical requirements
Knowledge of gravity and pump/siphon
dosed system requirements
Knowledge of timers and remote
Knowledge of bedding, testing, pipe
Knowledge of pump performance
specifications; total dynamic head in pressurized systems
Ability to make mathematical
Recommended Study References
Below is a list of study references that are recommended to assist the
candidate in preparing for the CIOWTS
of Wastewater Treatment Systems, CIDWT Ė
available for purchase through NEHAís
Bookstore. *Recommended reference
EPA Onsite Wastewater Treatment Systems Manual (PDF-
free to download
Building Design & Construction. Jack
Willenbrock, Harvey Manbeck, and Michael Suchar, (1998) Prentice-Hall.
System Checkup: The Rhode Island Handbook for Inspection and Inspection
Report Forms (PDF-
free to download
and DeCentralized Wastewater Management Systems. Crites
& Tchobanoglous. (1998) McGraw-Hill.
and Septic Systems, 2nd Edition. Max
& Charlotte Alth, Revised by S. Blackwell Duncan, (1992) TAB Books.
Handbook Revised Edition. Howard
of Terms by CIDWT (PDF free to download
Completing the Application
Applications must be completed and returned to NEHA for review at
least 4 weeks prior to the exam date. If an application is received less
than 4 weeks prior to when an examination is being given you may have to
schedule the exam for another date.
complete application should include:
Copy of Drivers License to verify age.
Work Experience Verification Form signed by a third
fees should accompany the NEHA
CIOWTS- Advance Level
Exam Scheduling and Locations
choose to schedule the CIOWTS examination in several different ways:
The CIOWTS exam is offered annually at the NEHA
Annual Educational Conference (AEC) & Exhibition.
State Affiliate and Regional Meetings periodically
offer the CIOWTS exam at their meetings/conferences. An up to date
listing of these meeting/conference offerings can be found at the
Candidates can choose to take the exam on computer through
By choosing this option candidates can schedule the examination at
their convenience at one of
testing locations nationwide. To find a
testing center near you please visit
Taking the exam at
not only offers the candidate flexibility in scheduling the exam,
but also allows the candidate to receive his/her unofficial scores
immediately following the conclusion of the exam.
Special test sites
may be arranged through NEHA in cooperation with the test vendor,
PTI. In order to accommodate requests for special test sites,
arrangements must be made a minimum of 6-8 weeks prior to the
requested date. The fee to set up a special test site is $350.00.
For groups of 10 or more candidates, the special test site fee is
waived. Please complete the Special Test Site Request form (Appendix
A) and return it to NEHA with your application.
Accommodations for Candidates with Disabilities or Impairments
NEHA is committed to ensuring that no individual is deprived of the
opportunity to take a credentialing examination solely by reason of a
disability or impairment. All test centers are fully accessible and
compliant with the American with Disabilities Act (ADA).
To make a request for special accommodations you must complete the
Accommodation Request Form and Documentation of Disability Related Needs
Form including the specific diagnosis of your disability; medical
records, or other written proof of the diagnosis by an appropriate
licensed professional; and the type of accommodation being requested.
All form and documentation must be returned to NEHA at least 8 weeks
prior to the scheduled test date. To receive a copy of the form please
If the forms are not returned to NEHA within 8
weeks prior to the scheduled test date your request for special
accommodations may not be honored or may be delayed.
With respect to all matters related to testing accommodations, NEHA will
only communicate with the candidate, professionals knowledgeable about
the candidateís disability or impairment, and the candidateís authorized
representative (if applicable).
Admission to the Exam
NEHA will send an
admission ticket approximately 2 weeks prior to your test date. The
admission ticket will detail the exam date and location, reporting time,
and starting time. Those that do not appear on the date of the exam at
the appropriate time will forfeit all exam fees. Persons arriving after
the examination has started may not be admitted.
you lost your admission ticket or have not received an admission ticket
at least 2 days prior to the test date, please contact NEHA immediately.
Only approved candidates will be admitted to the exam. No walk-in
applicants will be admitted.
test day please bring with you your admission ticket, photo
identification (i.e. driverís license or passport), and sharpened #2
FOR PEARSON VUE
NEHA will send you an authorization letter via e-mail when your
application is processed as approved. The letter will have your PTI ID
number and the Pearson VUE website to schedule a testing time.
On test day please bring your photo
identification (i.e. driverís license or passport).
The passing score
for the NEHA CIOWTS exam Levels A & B, is 70%. Your score will be based
on the number of questions answered correctly. If you are unsure of the
answer it is better to guess. You will not be given credit for any
question left blank.
Your exam results
will be mailed to you from the NEHA office 4-6 weeks after the
administration. To insure confidentiality, exam scores will not be
released over the phone, via fax or email.
Once you have
obtained the CIOWTS credential you must maintain it. To keep your
credential in good standing you must:
Earn a minimum of 12 hours of
continuing education every two years; and
Submit renewal fees for your
credential every two years ($125.00 Basic level; $125.00 Advanced