Manganese doesn't directly affect your health. In fact, manganese in small quantities is an essential nutrient in your diet. High levels of manganese, however, can lend your drinking water an unpleasant color and taste, forming brownish-black stains on glasses and other surfaces. If you suspect manganese in your drinking water, have it tested; contact your county environmental health department for a list of labs in your area. When manganese in your drinking water is in excess of 0.05 milligrams per liter, it's time to take corrective action. There are several options.
Consult test results to determine how much manganese you have in your drinking water.
Consider using a water softener if manganese content is below 5 milligrams per liter. Water softeners contain resins rich in sodium ions; the resin exchanges the sodium ions for manganese, magnesium and calcium ions in the water. Since they add sodium to the water, these units aren't suitable if anyone in your household is on a sodium-restricted diet. Water softeners are available at many home appliance and discount stores.
Consider using an oxidation/filtration unit if manganese content is below 15 milligrams per liter. These units can handle higher manganese concentrations than water softeners; they work by oxidizing iron and manganese to insoluble forms and filtering out the precipitate. Unlike water softeners, oxidation filtration units don't typically remove other water hardness ions like magnesium or calcium, although they can often remove arsenic as well.
Consider using a pressure aerator if manganese content is less than 25 milligrams per liter and you live in a warm area. Aerators can handle a higher manganese content than either of the two other options; they work by adding air to the water. The oxygen reacts with iron and manganese to form insoluble precipitates, which are then filtered from the water. This method doesn't add any chemicals to the water but it requires careful flow control. If water flows through the unit too rapidly, some of the manganese will not be oxidized, but if the flow is too slow, the water may become saturated with oxygen and corrode your system, potentially increasing lead content. Aeration can also lead to slime growths. Despite its disadvantages, aeration is one of the most cost-effective approaches since no chemicals are required.
Consider using chlorine treatment and filtration if your manganese content is very high. These systems inject chlorine, allow it time to react with the iron or manganese and filter out the precipitate. This method has as an advantage in its bactericidal effects; the chlorine also kills any bacteria present in the water. The chlorine can leave an unpleasant taste if calcite, sand or aluminum silicate filters are used; it's a good idea to install an activated carbon filter as well to remove any residual flavor.
Once you've chosen the best option based on the manganese content of your water and the options available to you, contact a home improvement store in your area to find out which brands they have available.