Onsite Wastewater Management Systems (OWMS)


On-Site Wastewater Management Systems (OWMS) go by a range of names, including septic tanks, onsite systems, and On-Site System Effluent Treatment (OSET) and many more.

Roughly 18% of New Zealand's population discharges its waste via OWMS.

The OWMS SIG (Special Interest Group) are a voluntary network of professionals involved in their manufacture, design, operation and regulation.



The Water New Zealand OWMS Special Interest Group aims to:

  • Encourage whole of system considerations OWMS
  • Support initiatives to ensure an adequately trained and qualified workforce
  • Advocate for cohesive regulatory landscape for OWMS
  • Provide a focal point for collaboration amongst OWMS professionals.

Our mission is to uphold Te Mana o te Wai by promoting sustainable, effective, and fit for purpose on-site wastewater management systems that safeguard environment and public health.

Membership of the groups is open to all Water New Zealand members. Activities of the group are overseen by a committee of up to fifteen group members and administered by Water New Zealand.

Committee membership is open to all group members, and new members are confirmed annually at the group’s Annual General Meeting.

If you are a Water New Zealand member and wish to belong to one of the special interest groups, make sure you are logged in to the Water New Zealand website, then simply send an email via the contact form at the bottom of this page to join our group. This will register you for notification of committee openings, as well as up to date correspondence on events, news, and other group activities.

If you are not a current member, visit our membership page for more information. Remember to tick the appropriate Special Interest Group box when completing the Membership Application form.

OWMS Resources

OWMS Committee

Become a member to be a part of OWMS SIG