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Certified Installer of Onsite Wastewater Treatment Systems (CIOWTS) Credential 


Exam and Application

Find a Credentialed Installer in Your Area (PDF)



What is the CIOWTS Credential

Through a cooperative agreement with the U.S. Environmental Protection Agency (USEPA), NEHA has worked with and various partner groups to develop a national credential to certify installers of onsite wastewater treatment systems. The credential covers all forms of installation and will be offered at both a basic and advanced levels.

The credential is designed to test the knowledge, skills and abilities needed for the successful installation of an onsite wastewater treatment system. Since it is a national credential, and state and local codes are not covered this credential is meant to enhance a state or local regulatory program.

A lot of time and effort is involved with maintaining an examination, a database of credentialed individuals, and tracking continuing education. NEHA hopes to make that task easier by offering this exam. For the professional installer, NEHA would like to give you this opportunity to set yourself apart from your professional colleagues and get the recognition you deserve for your quality work and knowledge.



Eligibility Requirements

To be eligible to sit for the CIOWTS credential examination, a candidate must meet the criteria as follows:

A. Be at least 18 years old.
And for Advanced Level CIOWTS exam
B. Have at least 2 years verified experience as an installer. Verification must be included in application—please see application for more details.


NEHA’s Credentialing Handbook

It is strongly recommended that you read NEHA’s Credentialing Handbook: Guide to Policies and Procedures for NEHA’s Credentialing Programs. This handbook  outlines all the policies you are expected to follow by being a NEHA credential holder. The handbook also outlines in further detail the procedures for applying for a credential, submitting continuing education, and maintaining your credential.

If you would like to request a hardcopy of NEHA’s Credentialing Handbook, please contact the Credentialing Department at (303) 756-9090 ext. 310, or email