With more than 30 years’ experience in the residential and commercial water treatment space, Mark Nelson is a Class 1 Drinking-Water Operator and a CBWA (Canadian Bottled Water Association) Certified Plant Operator. As founder and president of Nelson Water in Ottawa, Mark focuses on dealing with challenging water treatment system designs for problem water. He also heads the largest water bottling plant in the city of Ottawa with a delivery network throughout the Valley.

If you’ve ever turned on a tap and discovered that the water has a pungent, foul odor, it can be a cause for concern, This phenomenon can occur if you use private well water or your water comes from a municipal water treatment plant. Many people believe that the odor is a warning sign that their water has become contaminated. But, that may not be the case, and there are many reasons why water smells bad. The presence of bacteria is possible, but decaying organic material, elevated dissolved mineral content, and chemical reactions can all be a factor. The type of bad odor can also give you some clues about the possible cause. In this article, we will look at four common causes of stinky water and how you can fix the problem.

  1. A “Swimming Pool” or Bleach Odor

The Cause

This is a common complaint amongst homeowners that are supplied with water from the city. Most public water treatment plants use chlorine or chloramine (chlorine and ammonia) as a disinfectant. This has been a standard method to kill bacteria for many years, and the chemicals are added at the water treatment plant. As the water travels along the pipes to homes, it can lose some efficacy. So, the plant adds extra chlorine to keep the water clean throughout its journey. This is fine if you live far away from the treatment plant, but the higher chlorine levels can be very noticeable if you live closer. Higher than normal chlorine levels are not harmful to health, but they can make the taste and odor of the water unpalatable for drinking and cooking. High chlorine levels can also cause your skin to feel dry after washing, and some byproducts have been tenuously connected to serious health problems.

The Solution

The best way to remove chlorine from your incoming water supply is to install your own filtration system at home. A carbon filter can remove the taste of chlorine, and a reverse osmosis (RO) system can remove many contaminants, including chlorine. Using these two systems together will pre-filter the chlorine, remove it and then add some polish to make the water taste cleaner and fresher.

  1. An Earthy or Dirty Odor

The Cause

If you notice that your hot water smells earthy, dirty, or musty, you may have a bacterial problem. Don’t be alarmed, the bacteria will not be harmful to your health, but the dirty taste and musty odor will make the water unpalatable and hard to use. If you have iron bacteria in your well, you may notice that you have slime growing in your toilet or other plumbing fixtures. Iron bacteria is present when iron and oxygen mix together in a warmer environment. This type of bacteria fees on iron, and the slime is created to protect the bacteria. As iron bacteria dies, it generates the odor that you can smell and due to the warm temperatures needed, the water heater is a prime location.

The Solution

The best way to remove iron bacteria is to use a chlorine chemical feed system to reduce the bacteria levels and oxidize the iron. Then you can install an iron filter to remove the iron from your water. This will improve the taste and odor and reduce staining, that may also be a problem.

  1. A “Rotten Egg” or Sulfur Odor

The Cause

A sulfuric or “rotten egg” odor emanating from your faucet typically indicates the presence of sulfur bacteria. This foul odor is often a sign that a well has insufficient oxygen levels and hydrogen sulfide gas is produced. This can also occur in areas with a high concentration of sulfur, where a chemical reaction can take place in the groundwater. If you’re experiencing this odor only when running hot water, it’s likely that the source is in the water heater. If the odor is noticeable all the time, the problem is probably in the actual water supply.

The Solution

Because the root cause is a lack of oxygen inside the well, it’s essential to increase the level to remove the hydrogen sulfide gas. Installing an aeration system will combine catalytic carbon and dissolved oxygen to convert the gas to a solid form that can be filtered. Any gas that isn’t converted will be absorbed on the surface of the catalytic carbon. The sulfur bacteria must be disinfected with an oxidant, and this can be achieved with ozone or chlorine injection.

  1. A “Fishy” Odor

If you can detect a “fishy” odor in your drinking water, the likely cause is decaying organic matter. This organic material is naturally occurring, or you may have elevated levels of cadmium, barium, or chloramines in your water. Chloramine is a compound of ammonia and chlorine that is added to public water as a disinfectant in some areas. This is an effective disinfection method, but it can create a strong odor, and chloramine byproducts have been linked with serious health issues. Both cadmium and barium are metals that can be found in water due to pipe damage or contamination from fertilizers. The “fishy” odor will make water unpalatable to drink, but it doesn’t represent an immediate health threat. This odor does not indicate the presence of bacteria, but most people will not be able to tolerate the odor for long.

The Solution

The best way to deal with this problem is to remove the contaminants that are causing the odor. An effective method is reverse osmosis (RO), where the water is passed through a semi-permeable membrane under pressure. Only water molecules can pass through; the contaminants are left behind on the membrane surface and then flushed into the drain later. A carbon filter will add a final polish to the cleaned water to make it taste clean and fresh for drinking and cooking.

As you can see, the type of taste and odor that you can detect in your water will give you clues on the possible cause. If you’re concerned about a bad odor or other problem that is affecting your water quality, you don’t need to put up with it. Contact your local water treatment specialist, and they will be happy to help.