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Start-up Tips for Seasonal Groundwater Systems
Make your start up trouble-free by ensuring your system is clear of coliform bacteria before you begin serving water to the public.
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If your water system only operates during the warmer part of the year, it will soon be time to think about reactivating it. Preparations should begin 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 test to make sure the water system is free of coliform bacteria. If you don't already have one, purchase a chlorine residual test kit that measures from 0 to 4 mg/L of "free chlorine." Follow the steps below. Note: These steps do not address seasonal surface water systems.

Inspect the system. Install all components that may have been removed for winterization. Inspect all components of your water system for winter damage, including your distribution lines to locate all fixtures, review the Operations Manual and plans). If you identify any deficiencies, make the necessary repairs.

Winter erosion damage at springbox


For example, check to see that the well's sanitary seal is intact at the cap, as well as the screen on the vent. For springs, clear away dead and downed vegetation to eliminate cover for small animals, and check that the spring box lid is watertight and locked. Make sure the diversion ditch is clear of debris and directs surface water around the spring collection area. Check water storage tanks for damage to floats, valves, screens and wires (see Safety Precautions on the Disinfection page). Fix any tank leaks or other openings that might allow small animals such as mice or birds to come in contact with the stored water.

Activate the source(s). Make sure all drain valves are closed. Open or close main valves as shown in the Operations Manual. Even if a valve is already in the correct position for activation, this is a good time to "exercise" the valve by turning it back and forth through its full range. Finally, turn on the power to your source pump(s), or open the valve from the spring box.

Activate the treatment system (if applicable). Perform annual maintenance on pumps and components as recommended in the operations and maintenance manual. Turn on the power to the treatment equipment. For a chlorinated system, purchase fresh chlorine, mix fresh feed solution, replace or clean all lines and parts, and verify the feed rate of the feed pump. For other treatment, refer to the manufacturer and your operating procedures.

"Open" the system. Run water through the entire water system by opening hydrants, blow-offs, and faucets until flow is clear. Make sure pressure tanks are pressurized.

Disinfect. Disinfect and flush all sources, pressure tanks, storage tanks, and distribution lines. Leave chlorinated water in the system components and distribution lines for at least 24 hours. See System Disinfection Details.
Take care when flushing the chlorine from the lines and tank. Chlorine at this level will interfere with septic tank function and can injure or kill fish and amphibians. This water may either drain into the ground surface, or be dechlorinated with vitamin C (ascorbic acid) or sodium thiosulfate before discharging to septic tanks or near water bodies. Do not let this chlorinated water enter a stream, pond, or lake.

Flush. Once the sitting time is over, drain the components and flush the distribution lines with fresh water beginning with the taps closest to the source(s). Flush the system until the taste and odor of chlorine is not objectionable or the free chlorine residual is reduced to the amount needed for taking coliform samples (see next item). 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 20-30 psi of pressure in the distribution lines to prevent a back-siphon event. When you flush, keep chlorinated water away from all surface water such as lakes, streams, or ponds (see sidebar).

Collect coliform samples. After disinfection, take a preseason "special" bacteriological sample for testing at a certified laboratory (marking it "special" on the lab slip means that the information will be reported to the water system only, and will not count as required monitoring). Collect this sample when:
  • There is zero free chlorine residual measured throughout the system in a system that is not continuously chlorinated.
  • The free chlorine residual is at whatever level is "normal" or required for a system that is continuously chlorinated.
If the test results come back negative, the water system may be opened for public use. It is recommended to take another bacteriological sample about two weeks later to make sure the system still meets requirements.

Make sure the chlorine residual level has returned to the acceptable range before taking coliform samples or serving the water.

Respond to unsatisfactory coliform samples. If a coliform sample tests positive, re-evaluate the water system for cross connections or openings that would allow bacteria to enter. Repeat the chlorination procedure and look for problems in the system. If problems continue, call your regulating agency for assistance (see further information below).

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.

Also wise to do during system start up: See Start-up To-do List.


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