MANGANESE FLUSHING

Main Flushing

TGW periodically flushes the water mains to remove manganese buildup from the pipes. TGW will send a OneCallNow notification, and a large sign will be posted in the area being flushed.

During flushing:

Some members may experience a temporary drop in water pressure.
Water may appear discolored or have a temporary odor.
Avoid doing laundry during flushing hours.

If your water becomes discolored, run water from the hose bib or outside faucet closest to your water meter until the water runs clear.

Understanding Manganese & Discolored Water

Have you ever turned on your faucet and noticed that your water is no longer clear? Manganese is the primary cause of this discoloration and can cause water to change from clear to brownish or black.

Manganese is a naturally occurring element found in the earth’s outer crust. It can dissolve into groundwater, which means the water pumped from TGW’s deep groundwater wells naturally contains varying levels of manganese.

Typically, manganese is not noticeable because it remains dissolved in the water and is colorless. However, factors such as chlorine, heat, air, and sunlight can oxidize the manganese, causing it to form solid particles (precipitate). In this form, manganese can appear brown, black, or rusty in color.

Manganese occurs naturally in TGW’s groundwater and does not pose a health concern at the levels found in our water.

TGW’s Manganese Treatment Waiver

In 2014, TGW members voted, pursuant to the requirements of Title 22 of the California Health and Safety Code, not to treat or filter the water specifically to further reduce manganese levels. TGW subsequently received a treatment waiver from Santa Cruz County Environmental Health Services (EHS) allowing TGW to distribute water with manganese levels of up to 150 parts per billion (ppb), which is above the state’s 50 ppb secondary maximum contaminant level (MCL).

You can view TGW’s quarterly manganese levels for both the primary well and the Meadow Ranch Water Tank on our Water Quality webpage.

If Your Water Is Discolored

If you notice discolored water:

Turn on the outside faucet closest to your water meter and let the water run until it is clear.
Then run your indoor faucets until the water is clear.
If the discoloration continues, please contact TGW at 831-662-3204, ext. 2.

Filtration Resources

Occasionally, manganese buildup can break loose and enter the water distribution system, which may result in temporary discoloration. If you are interested in additional filtration for your home, the resources below may provide helpful information about water filtration systems and manganese removal:

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