Why does my water occasionally smell or taste funny?

Because of several possible environmental conditions, the quality of your drinking water may occasionally change. This may stem from drought or seasonal changes or algae blooms, or a number of other factors….and the effects may be short or long lasting. In any case, you may find the changes objectionable.

Many things cause odor and taste in water. These things may be associated with the water as it comes into your house, or it may be the result of something inside your home. Here are a few of the most common culprits:

Drains and Filters
A very common source of odor is the drain, or filters used prior to the faucet. Over time, organic matter can accumulate in the drains and filters and bacteria subsequently grow on these deposits. These bacteria can produce a gas that smells like rotten eggs or sewage or mildew. To make sure that the problem is not in the tap water, fill a glass with some water, away from the sink where the smell or taste has been noted, such as a hose bib. If the problem is in the drain or filter, the tap water in the glass should not have an odor or taste.

Iron and Sulfur Bacteria
Because iron is abundant in groundwater, it is not unusual to find iron bacteria there also. Iron bacteria are oxidizing agents. That means that during metabolism, the bacteria combine iron or manganese in water with oxygen. A side effect of this process is a foul-smelling brown slime which can coat wells, pipes, and plumbing fixtures. The slime isn’t a health hazard, but it can cause unpleasant odors, corrode plumbing equipment, and clog pipes. Iron bacteria grow better in slow- or non-moving water, so any dead-end pipe arrangements in a house can contribute to the growth of iron bacteria.

Water containing iron bacteria may have a yellow, red, or orange color. Rusty slime deposits may form in toilet tanks.

The sulfur bacteria include groups of both sulfur oxidizers and sulfur reducers. Of the two types, sulfur-reducing bacteria are more common. They break down sulfur compounds, producing hydrogen sulfide gas in the process. Hydrogen sulfide gas is foul-smelling (“rotten egg smell”) and highly corrosive.

Blackening of water or a dark slime coating the inside of the toilet tank may indicate a sulfur bacteria problem. Often, iron and sulfur bacteria live together symbiotically, and the resulting effects are accelerated and hard to distinguish.

Hydrogen sulfide gas may be present in the source water, especially in deep wells, but its source is more frequently inside your home. You may notice that the “rotten egg” smell is more prevalent when you first turn water after a long period of non-use. Or you may notice it especially from your hot water taps only. This is not unusual, because the gas accumulates and wants to escape your piping system as soon as the tap is opened.

One environment which frequently affects the quality of your water is your water heater. Sulfur bacteria love water heaters because they contain a “sacrificial anode.” This anode is a magnesium rod that helps protect water heaters by corroding instead of the tank lining. However, sulfur bacteria are nourished by electrons released from the anode as is deteriorates. In addition, the water temperature of the water heater may not be kept high enough to kill the sulfur bacteria (usually around 160oF).

Metals
Sometimes, drinking water has a slight metallic taste, a sign that dissolved metals are present. They may be present in the original groundwater (iron, for example), or they may be present as a result of the deterioration of piping. This is a serious problem if the pipes are older and are partially made of lead. Copper, although less toxic than lead, may also be a problem if pipes are being corroded.

Iron is usually the main culprit behind metallic-tasting water. It is not particularly harmful to health, but it can cause significant staining of plumbing fixtures, clothes, and basins.

Saltiness
High levels of dissolved solids can cause a general salty taste to the water. The most common ions associated with saltiness are sodium, potassium, calcium, and magnesium. Although not generally a health hazard, some of these ions may affect those with low tolerances to salt (such as sodium).

Chlorine
Chlorine (and sometimes bromine) is routinely used to disinfect the water supply. A small amount of residual chlorine is left in the water exiting the treatment facilities to make certain bacteria do not grow in the piping distribution system. Sometimes, however, additional chlorine is added by water systems to solve a particular problem, and its taste is more noticeable at your tap. The effects of this additional chlorine are usually short-term.

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