Why Does Polluted Water Smell Bad?

Polluted water can have a range of unpleasant odours, from rotten eggs to sewage, chemicals, and earthiness. These foul smells are often indicative of water impurities, with hydrogen sulfide gas, caused by sulfur bacteria or chemical reactions, being a common culprit. While sulfur bacteria are not harmful, hydrogen sulfide gas in the air can be dangerous at high levels. Other causes of bad-smelling water include iron, manganese, zinc, copper, and mercury, which may come from deteriorating metal pipes, as well as organic matter and certain minerals in groundwater.

Hydrogen sulfide gas

Hydrogen sulfide is a colorless gas that can occur naturally in groundwater. It is produced by sulfur-reducing bacteria, which use sulfur as an energy source and chemically change natural sulfates in water to hydrogen sulfide. These bacteria can flourish in oxygen-deficient environments such as deep wells, plumbing systems, water softeners, and water heaters.

The presence of hydrogen sulfide in water can be detected by its distinctive "rotten egg" smell and taste. While this does not always indicate poor water quality, it can be a sign of sewage or other pollution in rare cases. The gas is quite pungent, even at low concentrations, and can be detected by most people when the concentration is as low as 0.5 ppm. At higher concentrations, it can cause adverse health effects and is a leading cause of injury and suffocation among groundwater industry and wastewater sector personnel.

To remove hydrogen sulfide from water, various treatment methods can be used, including oxidation through aeration, chlorination, hydrogen peroxide, and potassium permanganate. For small private well systems, these methods are practical for sulfide content above 6 mg/L. Oxidizing filters can also be used to trap tiny particles of sulfur, and ozone treatment can create a chemical reaction that precipitates sulfur. In cases where hydrogen sulfide is causing an odor within the water heating system, modifying the water heater by replacing the magnesium corrosion control rod with one made of aluminum or other metals can help improve the situation.

Metallic smells

Polluted water can have a range of unpleasant odours, from rotten eggs to chemicals, and yes, even metal. Metallic-smelling water is often a sign of the presence of certain metals and minerals in the water supply.

Causes of Metallic-Smelling Water

Metallic-smelling water is usually caused by the presence of iron, copper, lead, manganese, zinc, or other metallic minerals. Groundwater is more likely to be affected by metallic smells than surface water, as it moves through rocks and sediments that can contaminate the water supply. Well water, in particular, is more likely to smell metallic as it is untreated and comes directly from the earth, leaving minerals like iron behind.

The age of your home and the type of pipes you have can also be factors. Older homes with lead or copper pipes are more likely to produce metallic-tasting water as these metals can contaminate the water. Additionally, low pH levels in water can cause household plumbing pipes to leach copper into the water supply, leading to metallic smells and green stains on bathroom fixtures.

What to Do

If you notice a persistent metallic smell in your water, it is recommended to have your water tested by a professional, EPA-certified company. They will be able to identify any issues and recommend appropriate solutions. One possible solution is to install a reverse osmosis system, which removes harmful chemicals and contaminants, improving the taste and smell of your water.

It is important to address metallic-smelling water as certain contaminants, such as lead and copper, can be harmful to your health if ingested frequently.

Bacteria in drains

Several studies have identified sink drains in medical-surgical intensive-care wards and cystic fibrosis units as possible sources of infection. The pipe work presents a variety of solid surfaces that are suitable substrates for biofilm formation. Biofilm has been implicated in a high proportion of slow-running drains in the United States. Domestic drains are subject to intermittent wetting, periodic feeding with a plethora of nutrients, hydrodynamic stresses of various intensities, and frequent subeffective antimicrobial treatments.

The location of a sink can affect the types of bacteria found. For example, a kitchen sink in a home may contain more bacteria than one in the bathroom and can contain up to 500,000 bacteria per square inch. Salmonella, Campylobacter jejuni, and Escherichia coli (E. coli) are some of the bacteria that can be found in kitchen sinks. Salmonella causes thyphoidal and gastrointestinal illnesses, while E. coli transmits food-borne illnesses via contaminated food or water. Staphylococcus aureus, or staph, can cause wound infections, food poisoning, pneumonia, and toxic shock. It thrives in wet conditions but can also survive in dry environments.

To get rid of harmful bacteria in drains, periodic drain cleaning and disinfection of sinks are recommended. While it can be challenging to eliminate bacteria in plumbing, a professional cleaning service can effectively remove any bacteria hiding in the nooks and crannies. Chlorination and treatment of the water supply can also kill bacteria.

Chlorination

The use of chlorine to disinfect water supplies was first reported in 1897 when a bleach solution was used to disinfect a water main in Maidstone, Kent, UK, following a typhoid outbreak. Chlorine disinfection was then rapidly implemented worldwide. In 1902, ferric chloride was used for 'coagulation' in Middelkerke, Belgium, in what was probably the first continuous application. In 1903, Vincent B. Nesfield, a British officer in the Indian Medical Service, developed a technique of purifying drinking water using compressed liquefied chlorine gas. The first continuous use of chlorine for disinfection in the US took place in 1908 at the Boonton Reservoir, which served as the supply for Jersey City, New Jersey. In 1910, Major Carl Rogers Darnall, Professor of Chemistry at the Army Medical School, gave a practical demonstration of this method, which became the basis for today's municipal water purification systems.

Chlorine is added to public water supplies to kill disease-causing pathogens, such as bacteria, viruses, and protozoans, that commonly grow in water supply reservoirs, on the walls of water mains, and in storage tanks. Chlorinated water can have a distinct chlorine taste and smell, which people usually get used to over time. The U.S. Environmental Protection Agency (EPA) limits the amount of chlorine in drinking water to levels that are safe for human consumption. The levels used for drinking water disinfection are unlikely to cause long-term health effects.

Organic matter

The organic matter could be decaying leaves, broken-down plants, or food waste that has accumulated in the drain over time. If the odour is recurring, it could be due to organic matter in the main water supply. If the odour is only present in certain faucets, the problem is likely in the fixtures or pipes supplying those specific faucets.

If the water smells musty, it could be caused by organic matter polluting the water. This can be addressed by sanitizing the plumbing system, including the water softener, or installing a reverse osmosis (RO) system to reduce the odour.

If the water smells like sewage, it could be due to bacteria left by food and soap in the drain or water heater. This can be resolved by disinfecting, cleaning, and flushing the drain or water heater.

If the water smells fishy, it could be due to bacteria infiltrating the water supply, and organic matter such as decaying leaves or broken-down plants could be the culprit. Contacting the water provider or installing a water filtration system can help address this issue.

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