Why Does My Well Water Smell? Understanding and Addressing the Issue

When anyone fills a glass with water from their well, what they really want is pure, sweet, healthy water. What they get is sometimes far from this ideal. Because of problems with a well, pump equipment, groundwater or household plumbing, well water can be smelly, stinky, discolored, bad-tasting or cloudy. Resolving these undesirable characteristics of well water requires determining exactly what is going on with your well or plumbing system. 

Smelly or stinky well water can sometimes be safe to drink, even if it is somewhat distasteful. However, it’s not possible to know about the safety of that water without determining what’s causing the smell. To help you get started diagnosing odor problems with your well water, ETR Laboratories offers this summary of well problems that cause undesirable smells. 

Bad Well Water Smells and the Contaminants That Cause Them 

There’s a surprisingly long list of possible causes of bad well water odor. Your first step toward determining the cause of the problem is categorizing the smell of your well water. Your own nose can lead you in the direction of finding the right solution. 

  • Sulfur or rotten egg smell: rotten egg smell can come from naturally occurring decay of minerals in soil and rocks or from sulfur bacteria in the groundwater or well. These sulfur bacteria produce hydrogen sulfide gas which has a rotten egg smell. 
  • Metallic smell: Traces of iron, copper, lead, zinc or manganese in the water can cause this smell. These traces can come from naturally occurring deposits in soil and rock but also from the pipes in your plumbing system. Water that is too acidic can leach metals out of pipes and plumbing fixtures and into your water.  
  • Earthy, musty smell: An earthy odor can come from the presence of dissolved minerals like iron, copper or lead. Iron or sulfur bacteria then eat these minerals and produce gases with earthy and musty smells.
  • Chemical smells: This can result from high iron content in the soil and rock around your well or industrial or agricultural chemicals seeping into your well from contaminated groundwater or surface water. 
  • Fish-like smell: A fishy smell is usually caused by contamination by barium or cadmium. These metals are naturally occurring and may simply be present in the soils around your well. If consumed in well water, they can accumulate in the body and cause health problems over time. If children are living in the home, it is important to filter cadmium out of the water as even low levels can disrupt bone growth. 
  • Petroleum, cucumber, sewage, rotten vegetation or mustiness: This amazing range of smells can be created by iron bacteria in your well. These bacteria occur naturally in shallow groundwater and surface waters. They are not known to cause disease but they can create conditions in which disease-causing organisms can thrive. 
  • Fuel smells: If there is any hint of gas, diesel or heating oil in your water, you may have a leak from an underground tank or runoff from drilling operations near your well. Stop using the water immediately and call a reputable well service company. 
  • Sewage: While sulfur bacteria or iron bacteria can cause a sewage-like smell, actual sewage contamination can also occur. This could happen if a well is located too close to a septic system or if well damage allows contaminated surface water to enter the well. 

Household Problems That Change the Smell of Your Well Water

While most smelly water has its source in your well, some problems with your household plumbing fixtures can also cause bad-smelling water. If you’re having trouble improving your water quality, look for these reasons your water could smell bad: 

  • Seasonal changes can affect the smell of your water. When there is sulfur in the groundwater, summer’s higher temperatures and reduced water levels can make the smell worse. 
  • Hot water heaters can grow sulfur bacteria, resulting in stinky hot water. This smell will be strongest when the hot water has not been used for a while, for example, while you are on vacation.
  • Not surprisingly, moldy-smelling water can be caused by certain types of algae, fungi, or bacteria lurking in your plumbing system.
  • Bacteria growing in a household drain can create a sulfurous or sewage-like smell.
  • Sink aerators can grow bacteria that transmit the smell to the water you drink or cook with.

Steps to Eliminate Household Causes of Bad Water Smells

If the origin of the smell seems like it is coming not from your well but from your household or plumbing system, follow these steps to eliminate the smell: 

  • Determine if the smell is coming from the hot water or cold water. Fill a glass with cold water and another with hot water. Take them to another room away from the plumbing, and smell each one. If the smell is only present in the glass of hot water, the problem is probably in the hot water heater. Start by draining the water heater and allowing it to refill. After a complete heating cycle, drain it again. If that doesn’t resolve the smell, have your water heater serviced. 
  • If the cold water has a smell, run the water for a few minutes. If the smell in cold water diminishes, the cause is probably in your plumbing system. You may have pockets of bacteria hiding in your system. Flushing the water entirely from your system followed by use of a disinfectant designed for this purpose can clean out bacteria and improve your water quality. Don’t forget to disinfect your water softener or other water treatment system, if you have one. 
  • If the water-related smell seems to be emanating from your drain, pour a quarter-cup of baking soda followed by a quarter-cup of white vinegar down the drain. This combination will bubble for a while. Boil a pot of water and pour this down the drain. 
  • Remove aerators from faucets and give them a good cleaning in half warm water and half white vinegar and then scrub to remove debris. While each one is off the faucet for cleaning, check the smell of the water to confirm that you are addressing the right cause. 

Smelly Contaminants That Also Cause Pump-Clogging Slime

As you investigate the source of your smelly water, be alert for bacteria that not only cause unpleasant smells but can create a slime that clogs wells, pumps, plumbing and irrigation systems. If you identify these bacteria in your water, it’s vital to get your system disinfected before slime can cause expensive damage. 

You might notice slime dripping from a faucet, feel slime on a surface commonly exposed to water, or see slime on the surface of water being released from your household plumbing system. Water testing will also alert you to the presence of these bacteria and should be done to determine which type of bacteria is present. 

  • Sulfur bacteria produce a slime and can promote the growth of other bacteria such as iron bacteria. 
  • Iron bacteria can create slime as it oxidizes both iron and manganese in the water supply.

Eliminating these slime bacteria requires strong disinfection starting with chemical shocking of the well. Severe contamination may require professional removal and disinfection of the pump and scrubbing of the well casing. 

How to Get Bad Smells Out of Your Water Well

Some of the problems listed above will require a thorough well disinfection while others require well repair or adding a filter or treatment system. Selecting the right solution starts with the correct identification of the cause of the problem. Once you have identified what is contaminating your well water, check out these solutions.

Sulfates: Sulfates causing rotten egg smells are a combination of sulfur and oxygen that are found in soil and rock in many areas. Removing these elements requires distillation, reverse osmosis or activated carbon filters designed specifically for this problem. 

Metallic smells from iron, copper, lead, zinc or manganese: A water softening unit with an ion exchange process can remove iron and manganese. Copper, lead or zinc can be removed with reverse osmosis, ion exchange or activated carbon filters. If the problem is caused by acidic water that is leaching metals out of plumbing fixtures, a neutralizing filter can be added to your system to correct the pH. 

Chemicals: Chemical contaminants can be reduced or eliminated with activated carbon filters. The source of chemical contamination should also be located. A damaged well casing can allow surface water contaminated with agricultural or industrial chemicals like pesticides, herbicides or fire-fighting foams to make their way into your well water. Make sure your well is located at least 100 feet from any areas that receive pesticides, herbicides or other chemicals. It may be necessary to relocate a well away from sources of chemical contamination. 

Barium or cadmium: These naturally occurring metals can be removed with reverse osmosis systems to eliminate a fishy smell.

Fuel: Check for any drilling operations in your area. Have your property inspected for abandoned underground fuel tanks. If a fuel leak or contamination source is located, your well may need a new lining installed. In extreme cases, the well may need to be relocated. 

Sewage: It is important to have the well checked for integrity. A cracked or broken casing can allow surface water contaminated by human or animal sewage to enter the well. Wells should also be located at least 50 feet from septic tanks and 100 feet from any animal enclosure.

Remember that any filtration, softening or other water treatment system requires regular maintenance. Follow the manufacturer’s instructions to keep the filter or treatment system clean and working properly. 

Prevent Smelly Well Water with the Right Annual Testing

While water wells are “out of sight, out of mind” for many owners, the fact is that they require regular maintenance to stay healthy. Annual testing of wells is essential to ensure that the well is in good repair and that no new sources of contamination have shown up. According to the Environmental Protection Agency, a contaminated plume of groundwater can travel several miles from its source. Only professional water testing can tell you if your well is being affected by a new contamination source. 

ETR Labs has provided tens of thousands of private well owners with detailed, accurate testing so they could solve their smelly water problems. Not only this, but our personal consultations and advice help well owners choose the right type of filtration or water treatment system to correct problems. We have also advised well owners on other problems to look for that might not be so obvious, such as small gaps in well caps or electrical connections that permit insect or small animal infiltration. Check out our most popular water tests here

Our service starts with testing for contaminants like coliform or other bacteria, metals like arsenic, barium or uranium, alkalinity, radon or industrial chemicals like benzene, carbon tetrachloride or toluene. Our follow-up consultations at no extra charge are welcomed by customers with an urgent need to correct their water quality.

Maintain a Regular Schedule of Well Maintenance for Safety and Health

The Centers for Disease Control and Prevention recommends that each well be tested annually for cleanliness, coliform bacteria, total dissolved solids, pH, nitrates and nitrites, and any other contaminants that might be of local concern, such as animal waste or industrial chemicals. 

Annual disinfection is recommended and a water well should be thoroughly cleaned at least once every five years. The entire system should be thoroughly inspected at least once every ten years, or more frequently if there is a problem with contamination. A private water well can be expected to provide clean, healthy water for 20 years if it is properly maintained. Inspect a wellhead several times a year and keep it clear of brush or debris. 

ETR Laboratories is dedicated to helping private well owners procure clean, healthy water with water testing and other services. Contact us if you need help for your well.