Group B Public Water Systems - Design

Designing a New or Expanding Water System

If you plan to design a new Group B Water System, or expand an existing Group B water system, information on this webpage will help.

General requirements and applicability

The Group B main page has general information about the rule change.

Before starting your design, you need to know if the local health jurisdiction (PDF) or our department will review and approve your project. The LHJ may have additional requirements beyond the state rule requirements. Use the LHJ link above to find contact information for your county.

If you are not a professional engineer, then your first step is to hire one. Group B system designs submitted to us for review and approval must be submitted by a professional engineer. Some LHJs allow exceptions for non-engineers to complete Group B system designs, so make sure you know who is reviewing your project.


Water systems designed to serve 10 to 14 dwelling units

If you plan to serve 10 to 14 dwelling units (residential service connections) with your Group B system, then you must follow the design, planning, and engineering requirements found in chapter 246-290 WAC for Group A systems. Again, your first step would be to hire a professional engineer to begin the process for getting your system design completed and approved.


Group B Water System Design Guidelines and Workbook

We have updated the key resources you will need to successfully complete your new or expanding Group B Water System. The Group B Water System Design Guidelines (PDF) walk you through the requirements, and provide engineering recommendations. The Group B Workbook (Word) is an easy-to-use submittal document that will help you submit a complete packet for our review and approval.

Forms and templates

You will need certain forms and templates to complete your submittal. Please refer to the Group B Water System Design Guidelines (PDF) and Group B Workbook (Word) for more information.

If you need help

Your engineer will be working directly with our regional engineers that review the submittals for new and expanding Group B systems.

If you have other questions, visit our webpages that have general information about Group B water systems or the operations and maintenance of a Group B water system.

More Resources