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 updated the key resources you need to successfully complete your new or expanding Group B Water System. The Group B Water System Design Guidelines 331-467 (PDF) walks you through the requirements and provides engineering recommendations. The Group B Workbook 331-468 (Word) is an easy-to-use submittal document that helps you submit a complete packet for our review and approval.

Forms and Templates

You need certain forms and templates to complete your submittal. Please refer to the Group B Water System Design Guidelines 331-467 (PDF) and Group B Workbook 331-468 (Word) for more information.

If You Need Help

Your engineer will work directly with our regional engineers who review 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