Published: June 24, 2008 07:12 pm            

Get a clear answer on what's in your water

-- What is that orange gunk in my water?

That orange slimy stuff (biofilm) is formed by iron bacteria. Iron bacteria may also cause orange, red or yellow water; slime on the inner walls of the toilet tank or an unpleasant odor to your water.

-- Is it dangerous?

No, although water with iron bacteria often has an odor similar to fuel oil, cucumbers or sewage. The odor and gunk is most noticeable in the morning or after long periods of disuse of your water supply. It is not a health risk. It can however be aggravating.

-- What other problems are associated with iron bacteria?

Additional undesirable effects may be: clogging of sprinklers, pumps, dishwashers and filters. A slime coated system may have reduced water flow. This may be due to constriction in the pipes or plugging of the well screen. Red, yellow or brown stains on laundry; porcelain sinks, tubs, toilets; and dishes may occur. You may also get a metallic iron flavor like the taste of blood (iron flavors blood too). Coffee and tea made with high iron water tastes lousy and sometimes has a black precipitate. Potatoes cooked in high iron water turn black.

Sometimes holes in the metal walls of pipes may occur due to sulfur bacteria that take up residence in the iron bacteria's slime. The sulfur bacteria produce acids that corrode the metal pipe.

-- Where do the iron bacteria come from?

They are natural in our surface environment. There are 18 genera of bacteria that are called iron bacteria. They can be found in soil, lakes, ditches, and marshes. It is believed that they are introduced to the well when the well is drilled or worked on. Tools, pipe, pump, water anything put down into the well for drilling or repair should be disinfected. It is easier to prevent introduction than to get rid of the bacteria after the fact since the slime makes it hard to kill all of the bacteria.

-- How do you treat for iron bacteria?

Generally shock chlorination is used. Scrubbing the casing with a wire brush to dislodge the slime is often recommended following removal of the pump and components but this is time consuming and expensive. A concentration of 250 parts per million chlorine residual (half gallon of bleach per 100 gallons of water) is recommended. Call your local Health Department for complete directions or hire a well driller to do the job. Unfortunately, you will probably need to repeat this in time, since usually some bacteria survive and their populations will build back up again.

-- What other forms of iron in water are there?

Water that comes out of the tap clear but turns red or brown after standing is "ferrous" iron, also called "clear-water" iron. If it is red or yellow when you turn on the tap, this is "ferric" iron, called "red-water" iron. There is also "organic" iron which is usually yellow or brown but sometimes clear. Water containing iron bacteria is called "bacterial" iron. The form of iron is a factor in choice of treatment.

-- Treatments?

Clear-water iron (ferrous iron) Water softeners are commonly used and able to readily remove 2-5 milligrams/liter (mg/L). Ion exchange water softeners add sodium to the water which can be a problem for some folks. A potassium ion exchange may be used for individuals with a sodium problem.

Red-water iron (ferric iron) Sediment filters, carbon filters or water softeners will remove this iron but filters and systems must be regularly maintained as they plug quickly. A manganese greensand filter (called iron filter) is a better choice. For high levels (greater than 10 mg/L), aeration or chemical oxidation (adding chlorine in the calcium or sodium hypochlorite form) is recommended.

Organic iron Organic iron is often present along with tannins. This may be a problem in very shallow wells or in wells affected by surface water. Organic iron is a compound formed from an organic acid and iron. Organic iron and tannins are difficult to treat with water softeners, aeration systems and iron filters. Chemical oxidation followed by filtration is sometimes recommended.

Bacterial iron treatment has already been discussed above.

-- Testing?

The partial chemistry test conducted by the Health Department will give the iron content along with nitrate, nitrite, hardness, sulfate, chloride, sodium and fluoride of your water. Some certified labs also run iron tests. Unlike our recommendation for annual testing for nitrate, nitrite and coliform bacteria you do not need to test for iron every year unless you are monitoring a problem well.

Free testing for all drinking water well owners: For a free nitrate, nitrite and triazine pesticide screening of your water, go to your local MSU Extension office, get a sample bottle and sampling directions and return your sample to them on July 14 (one day only). If you want to save an extra trip to your Extension office, go to www.msue.msu.edu/portal Click on: offices/staff on left side under information, then click on Grand Traverse County, then click Michigan Groundwater Stewardship Program on left side under local information, then click "Sample Information Sheet" under Free July 14 Water Testing.

For more information, call 922-4625.

        

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