Common Sources of Tap Water Odors
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Common Sources of Tap Water Odors

People are very sensitive to any type of odor coming from tap water since it is used for cooking, cleaning, and drinking. Many times the odor is a by-product of the water treatment process, but it could also be from the piping in your home, or the ground water if you have well water. This article will list various sources of odors in tap water and some corrective measures.

People are very sensitive to any type of odor coming from tap water since it is used for cooking, cleaning, and drinking.  Many times the odor is a by-product of the water treatment process, but it could also be from the piping in your home, or the ground water if you have well water.

In most cases the odor and the cause is harmless as in the case of the water treatment, but other times the smell is an indication of a more serious problem.  If your tap water has an unusual odor, or the odor has changed recently you should check for these potential contaminants.

Odor Sources

Water Supply Lines – As the plumbing system ages the pipes that carry the water can begin to corrode.  When this happens, the metal from the pipes dissolves into the water itself.  Copper, iron, and lead are the main metals that have been found in tap water and each metal has a distinct smell and taste which can be altered by the other substances found in the water.  These metals, depending on the type and concentration, can cause serious illness to anyone who drinks the water with lead being the most dangerous. If you suspect lead in your water, have it tested right away and refrain from drinking it. High quality water filters can remove most metals from tap water.

Brown, rust colored water is due to iron and oxygen in the water, and can be from old municipal water mains in the street. Iron bacteria may also be present which can cause red, yellow, or orange colored water, rust-colored deposits on plumbing fixtures, and slime on the inside of toilet tanks. The smell produced by these bacteria can resemble fuel oil, cucumbers, or even sewage, and the odor can be stronger in the morning or after extended periods of non-use.

Copper can cause metallic odors and taste if the water has a low pH or if the copper water lines are very old. Blue or green staining in sinks is an indication of copper corrosion as are pinhole leaks.  Lead typically comes from the solder used in older plumbing lines up to the 1990s.

The rotten-egg odor is caused by hydrogen sulfide in the water. Sulfur-reducing bacteria, which use sulfur as a food source, are the primary producers of large quantities of hydrogen sulfide. Sulfur-reducing bacteria live in oxygen-deficient environments such as deep wells, plumbing systems, water softeners and water heaters. Occasionally, a hot water heater is a source of hydrogen sulfide odor due to the magnesium anode rod that can chemically reduce naturally occurring sulfates to hydrogen sulfide. Aluminum anode rods can reduce rotten-egg odors.

Microorganisms - If your tap water has a strange odor, it could be caused by microorganisms living in the water.  The main source is algae and algal blooms.  While these organisms are typically not harmful, they can still cause an unpleasant odor.

If you do have algae and choose to treat it, the treatments can also cause unpleasant odors in your tap water.

Environmental contaminants - This is typically the least common source of foul odors, but it is probably the most harmful.  Seepage of environmental contaminants such as sewage or storm water runoff can cause tap water to smell bad. 

Environmental contaminants such as PCBs, mercury, lead, arsenic, and other heavy metals held in the soil can enter the water supply. If you live in an area with a high concentration of these contaminants, follow the advice of government officials when it comes to water safety to prevent serious illness.

Water Treatment – Most municipalities use various chemicals to treat drinking water. The chemicals used depend on the substances found in the local water supply. The most common chemical used is chlorine which removes oxygen from the water and kills bacteria and other microorganisms. Occasionally there will be higher than normal concentrations of chlorine when water is first treated and then pumped into water storage tanks.  The odor from the chlorine can be stronger when the water company is attempting to treat a certain problem.

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Comments (1)

Oh so helpful Daniel. Mostly my tap water is fine but occasionally it isn't. Good to know all the facts.