Group B Public Water Systems - Seasonal

Start-up and Shut-down Procedures for Seasonal Water Systems

Start up

If you have a seasonal water system, start preparing your water system to open at least one month before you plan to serve water to customers. You will need time to evaluate the condition of your water system, make repairs, disinfect, and ensure the water system is free of coliform bacteria. Purchase a chlorine residual test kit that measures from 0 to 3.5 parts per million (ppm) of “free chlorine” if you don't already have one. Follow the steps below. If you have questions, call your regional engineer.

1. Inspect the water system

Inspect all components of your water system, including your distribution lines. The Small Water System Start-up Shut-down Self-Inspection Checklist, DOH 331-312 (PDF) will help you identify potential problems. Repair any deficiencies you identify before you serve water to customers.

2. Activate the source and treatment

  • Turn on the power to your pump and treatment equipment.
  • Read the source meter and record the reading on the checklist. If you don't have a source meter, arrange to have one installed as soon as possible.
  • Disinfect the level probe, measure the static water level, and record the result on the checklist. If you don't have a probe, ask your local health department if you can borrow one.
  • Chlorinated systems: Purchase fresh chlorine, mix fresh feed solution, replace or clean all lines and parts, and verify the feed rate of the feed pump.
  • Other treatment: Refer to the manufacturer, your operating procedures, or call a licensed professional engineer or other water treatment specialist.

3. Operate the water system

Run water through the entire water system by opening up hydrants, blow-offs, and faucets. Make sure all pressure tanks are pressurized.

4. Disinfect and flush

  • Disinfect and flush all sources, pressure tanks, storage tanks, and distribution lines. Refer to Emergency Disinfection of Group B Systems for guidance.
  • Chlorinate your system. Leave chlorinated water in the lines for at least 24 hours.
    • If anyone could drink the water during the chlorination process, use 2 ppm of unscented household bleach (about ¾ cup) for every 1,000 gallons of water in the system.
    • If no one has access to the water, use 5 ppm of unscented household bleach (about 1 ½ cups) for every 1,000 gallons of water in the system.
  • Beginning with the tap closest to the source, flush all distribution lines thoroughly. Make sure you don't damage a pump by drawing water down below a pump intake level. If you have a storage tank, watch the water level in the tank to ensure you maintain 30 pounds per square inch (psi) of pressure in the lines. When you flush, keep chlorinated water away from all surface water such as lakes, streams, or ponds.

5. Collect coliform samples

  • Measure the chlorine residual from taps or blow-offs throughout your distribution lines.
    • Untreated systems must not have any detectable free chlorine when coliform samples are collected. If you do detect chlorine, re-flush before you collect coliform samples.
    • Chlorinated systems should have free chlorine residual at the “normal” operating level for the system (and greater than 0.2 ppm) when samples are collected.
  • Collect at least one coliform sample. You should collect samples at least two weeks prior to opening.
  • Refer to the Coliform Sampling Procedure* brochure, DOH 331-225 (PDF) for instructions.
  • For type of sample on your lab slip, check “Sample Collected for Information Only.”
  • Re-evaluate the water system if any samples are unsatisfactory. If you need assistance, call a licensed professional engineer or other water treatment specialist.

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 coliform bacteria.

    6. Provide drinking water

    When all the sampling results are satisfactory and the water system is operating as it should, you can start serving drinking water to the public.


    Shut down

    When you are ready to close your seasonal Group B water system for the year, you should inspect it, clean it, and protect it so it will be ready when you re-open the next season. If you perform a few shut-down procedures, your water system will be in good shape and need fewer repairs and maintenance work before you re-open it.

    1. Evaluate the water system

    2. Drain and repair the storage tank

    • Drain all water out of the storage tank.
    • Inspect the tank for cracks and make any needed repairs.
    • Clean out any sediment accumulated on the bottom of the tank.
    • Check the reservoir for openings that could allow rodents, insects, or other contaminants to enter, and correct as needed. Inspect vents and overflows, and re-screen if needed.
    • If you see growth on the walls of the tank, you may choose to spray them with a concentrated chlorine solution of 50 parts per million (ppm) and let it sit for four hours. You will be chlorinating the tank prior to re-opening, so this step may or may not be necessary. Caution! Chlorine may be hazardous in a confined space. Only a professional or a person with confined space training should perform this optional task.

    3. Pressure tanks

    • If there is a potential for freezing, drain your pressure tank(s) when not in use. Contact the manufacturer if you need instructions on how to do this.
    • If freezing is not an issue, you may choose to drain the tank(s) or leave it full. If you leave it full, it is important to chlorinate the full volume of water in the tank prior to start-up.

    4. Shut down the source(s)

    • For most sources, you will want to turn off the power supply in the off-season. Be sure to take steps necessary to protect your source, equipment, and structures. Consider freezing, vandalism, vermin, flooding, severe rain, and so on. Depending on your situation relative to these factors, you may need to leave the power supply to the source turned on.
    • If you are closing the system through the winter, take steps to protect the system components from freezing. If possible, use Styrofoam to insulate. Shredded paper or fiberglass insulation may attract vermin, so do not use those materials to winterize.
    • Check the source(s) for openings that could allow rodents, insects, or other contaminants to enter and correct as needed.

    5. Shut down treatment

    • Turn off the power to all treatment systems.
    • Discard unused chlorine solutions and stock.
    • For other treatment systems, follow the manufacturers' instructions for equipment, chemicals or filter media not in use for long periods.

    6. Protect the distribution system

    • Do not leave taps open in the off-season.
    • Never use anti-freeze in your water system because it is a health hazard.
    • Exercise valves and ensure they're working. Repair if needed.