Group B Public Water Systems - Operations

Operating Your Water System

As an operator of a Group B water system, you have the responsibility to your consumers to provide a continuous supply of safe drinking water. Meeting your responsibilities may include sampling and resolving problems, responding to emergencies, and conducting routine maintenance.

If you're having operations or maintenance problems, contact one of our approved Satellite Management Agencies (SMAs) (PDF). SMAs operate all over the state, and may be able to help with services such as:

  • Sampling.
  • Repair.
  • Maintenance.
  • Inspection.
  • Oversight of sub-contractors.
  • Project coordination.

Water quality sampling

Although not required, ongoing monitoring is necessary to help ensure your system provides safe and reliable drinking water. We recommend you sample your system at least annually for coliform bacteria and nitrate. Here are instructions to help you successfully monitor your system's water quality:

Make sure you check the box marked "routine" for the type of sample.

For a list of certified labs, visit the state Department of Ecology. Under "Location," select your state, city, and county. Scroll down and click on "Show results." Click on the name of a lab to see the tests it performs. Call the lab to make sure it's accredited to analyze for the drinking water parameter you want analyzed.

Responding to water quality problems


If your coliform sample comes back with E. Coli, notify your customers immediately using the Coliform consumer notice (Word).

When you have coliform bacteria in your system, take immediate steps to solve the problem. Visit these links with information that may assist you with your “next step” actions:


If your nitrate sample comes back above 10.0 parts per million, notify your customers immediately using the Nitrate consumer notice (Word)


If your arsenic sample comes back above 10.0 parts per billion, notify your customers immediately using the Arsenic consumer notice (Word)

For more information, visit our Coliform, Nitrate, and Arsenic pages. We also have more information on the General Information webpage

Preparing for an emergency

You should review Emergency Response Planning Guide for Group B Water Systems, DOH 331-211b (Word) before an emergency occurs. This document includes templates to help develop your water system's plan. This document includes templates to help develop your water system's emergency preparedness and response plan.

Visit our Group B Emergencies page for more information.

Seasonal Group B systems

If your Group B system is not used year-round, it will be prone to contamination if you don't take specific steps to prevent problems. We've created recommendations for seasonal start-up and shut-down procedures

Routine maintenance

As an operator of a Group B system, routine preventative maintenance can help prevent problems. Knowing the needs of your system and taking action to meet those needs will improve your system's reliability and reduce long-term costs. We've created a maintenance guideline (PDF) specifically for Group B systems to use.

In addition, many national organizations have developed useful guidance for routine maintenance, including: