Why Does My Water Smell Like Rotten Eggs?

Why does my water smell?

Having clean and odourless tap water is crucial for maintaining a healthy and comfortable living environment. However, if you’re asking yourself “why does my water smell” of rotten eggs or sulphur, it can be quite unpleasant and concerning. In this article, we will explore the common causes behind this issue, discuss the best methods to remove the sulphur smell from your water and provide information about the operational requirements of the equipment involved. By following these recommendations, you can effectively eliminate the sulphur smell and enjoy fresh and odour-free water in your home.

Sulphur requires careful treatment in order to address the question why does my water smell

Sulphur is a chemical compound. As such it responds differently to various influences. Ph, TDS, O2 content, all affect H2S processing. You need to know some of the chemistry of your water supply, or you are just guessing and hoping that you get the right sulphur removal technology. That might be an expensive way to learn. Perhaps you should read on.

Our first task is to determine “why does my water smell?”

The presence of a sulphur smell in tap water can be attributed to various factors. It’s important to identify the source before determining the most suitable solution. Here are some common causes:

1. Presence of Hydrogen Sulphide Gas

The Most Common Cause of the Rotten Egg Smell in Tap Water

Have you ever turned on your tap and been greeted by a foul odour resembling that of rotten eggs? If so, you’re not alone. The presence of a rotten egg smell in tap water is a common issue that many people experience. In this article, we will delve into the most common cause of this unpleasant scent and provide you with a comprehensive understanding of why it occurs.

Hydrogen Sulphide Gas: The Culprit

The most frequent cause of the rotten egg smell in tap water is the presence of hydrogen sulphide gas. This gas, also known as H2S, is responsible for the pungent odour that can taint the water. But where does this gas come from, and how does it find its way into our water sources?

Decaying Organic Matter: A Breeding Ground

One of the primary sources of hydrogen sulphide gas in tap water is decaying organic matter. Leaves, algae, and other organic materials that find their way into water sources such as wells or reservoirs can break down over time, producing this foul-smelling gas as a byproduct. As the organic matter decomposes, it releases hydrogen sulphide into the water, which ultimately reaches our taps.

Bacteria and Their Metabolic Processes

In addition to decaying organic matter, bacteria present in the water can also contribute to the presence of hydrogen sulphide gas. These microorganisms possess metabolic processes that produce the gas as a byproduct. Certain types of bacteria thrive in environments with low oxygen levels, such as groundwater, and are capable of generating hydrogen sulphide during their life cycles.

Identifying the Source

If you detect a rotten egg smell in your tap water, it is crucial to identify the source of the issue. This will help you determine the best course of action to rectify the problem. In some cases, the cause may be related to the water supply itself, while in others, it could be specific to your plumbing system.

Addressing Water Supply Issues

When the rotten egg smell is present in all faucets throughout your home, it is likely originating from the water supply. Municipal water systems can sometimes have elevated levels of hydrogen sulphide due to natural factors or the treatment process. In such cases, contacting your local water provider is recommended to seek guidance on resolving the issue.

Plumbing System Concerns

If the smell is isolated to certain faucets or fixtures, such as the hot water taps, the problem may lie within your plumbing system. An anode rod in a water heater can react with the sulphides in the water, producing hydrogen sulphide. Additionally, bacteria can accumulate in aerators, shower-heads, or other areas with stagnant water, leading to the odour. Cleaning or replacing affected components can often eliminate the smell.

Prevention and Treatment

Preventing the rotten egg smell in tap water involves addressing the root causes. Regular maintenance of your plumbing system, including flushing and cleaning fixtures, can help prevent the buildup of bacteria. Installing activated carbon filters or other water treatment systems can also reduce hydrogen sulphide levels and improve the overall quality and taste of your tap water.


The presence of a rotten egg smell in tap water can be off-putting and concerning. Understanding the common causes, such as decaying organic matter and bacteria’s metabolic processes, empowers you to take appropriate action. By identifying the source and implementing preventive measures or seeking professional assistance, you can ensure that your tap water is free from unpleasant odours and safe for everyday use.

2. Chemical Reactions

In some cases, the sulphur smell in tap water can result from chemical reactions. For instance, when naturally occurring sulphates come into contact with certain bacteria or chemical substances, they can produce hydrogen sulphide gas.

3. Corroded Pipes or Plumbing System

Corrosion of pipes or plumbing fixtures can also contribute to the presence of sulphur odour in tap water. When water comes into contact with corroded metals like iron or manganese, it can produce hydrogen sulphide gas.

Removing the Sulphur Smell from Your Water

Now that we understand the possible causes, let’s explore the best ways to remove the sulphur smell from your tap water:

1. Chlorination

Chlorination is a common method used to eliminate the rotten egg smell from water. By introducing chlorine into the water supply, it oxidizes hydrogen sulfide gas, converting it into a soluble form that can be easily filtered or removed.


In this comprehensive guide, we will delve into the process of chlorination and how it effectively reduces sulphur odours in households. We will explore the equipment involved, the operating parameters, the extent of sulphur removal, and the time required for the process. By the end, you’ll have a clear understanding of how chlorination can eliminate unpleasant sulphur odours from your home.

Understanding Sulphur Odours

Sulphur odours are a common issue that many households face. These odours are often characterized by a pungent smell similar to rotten eggs. The presence of sulphur compounds, such as hydrogen sulphide (H2S), is responsible for these unpleasant odours. They can originate from various sources, including contaminated water supplies or anaerobic bacterial activity in plumbing systems.

Chlorination: The Solution to Sulphur Odours

How Does Chlorination Work?

Chlorination is a highly effective method for treating water and reducing sulphur odours. It involves the addition of chlorine, typically in the form of sodium hypochlorite (NaOCl) or calcium hypochlorite (Ca(OCl)2), to the water supply. Chlorine is a powerful oxidizing agent that reacts with the sulphur compounds, effectively neutralizing their odour-causing properties.

When chlorine is introduced into the water, it forms hypochlorous acid (HOCl), which further dissociates into hydrogen ions (H+) and hypochlorite ions (OCl-). These ions attack the sulphur compounds, oxidizing them into non-volatile compounds that do not produce foul odours. The resulting by-products are usually harmless sulfates or other soluble compounds.

The Equipment Involved

To implement chlorination for sulphur odour removal, specific equipment is required. Here are the primary components involved:

Chlorine Feed System

A chlorine feed system is responsible for accurately and consistently adding chlorine to the water supply. It typically consists of a chemical storage tank, a metering pump, and appropriate control mechanisms. The metering pump ensures precise dosing of chlorine, while the control mechanisms monitor and maintain the desired chlorine concentration.

Injection Point

The injection point is the location where the chlorine is introduced into the water. It is strategically positioned to facilitate thorough mixing of chlorine and water, ensuring effective treatment. Common injection points include the water main or a designated point within the plumbing system.

Contact Tank

After the chlorine is injected, the water is directed to a contact tank. The contact tank allows sufficient time for the chlorine to react with the sulphur compounds and neutralize their odours. The duration of contact time may vary depending on the extent of the odour issue and the specific equipment used.

Operating Parameters

To achieve optimal results with chlorination, certain operating parameters should be considered:

Chlorine Residual

The chlorine residual refers to the concentration of chlorine remaining in the water after the treatment process. Maintaining an appropriate residual level is crucial to ensure effective odour control. The recommended residual concentration typically ranges between 0.5 to 1.0 parts per million (ppm).

pH Level

The pH level of the water can influence the efficiency of chlorination. Generally, a pH range of 6.5 to 7.5 is ideal for maximizing the oxidation of sulphur compounds. If the water’s pH falls outside this range, pH adjustment techniques may be required.

Water Temperature

Water temperature can affect the reaction rate between chlorine and sulphur compounds. Warmer water temperatures generally facilitate faster reactions. However, it is important to follow manufacturer guidelines and maintain appropriate temperatures.

Info Box

Chlorination systems are considered to be “engineered systems.” They need to be set up specifically in consideration of your water pressure and flow rates, daily water consumption, and other constituents in the water that the chlorine might interact with. Please contact me directly HERE to discuss the proper application of chlorination should that be your preferred water treatment system.

2. Activated Carbon Filtration

Activated carbon filters are highly effective in removing unpleasant odors, including the sulphur smell, from tap water. These filters work by adsorbing the compounds responsible for the odor, leaving the water fresh and clean. It’s important to choose a carbon filter specifically designed to target hydrogen sulfide.

Activated Carbon Filters: How Do They Work?

Adsorption Mechanism

Activated carbon filters work based on the principle of adsorption. The activated carbon material contains numerous tiny pores and a vast surface area, enabling it to attract and capture various impurities, including sulphur compounds. When water passes through the filter, the sulphur compounds present in the water adhere to the carbon surface, effectively removing them from the water stream.

Selection of Carbon Filters

To target sulphur odours specifically, it is important to choose activated carbon filters that are designed to address hydrogen sulphide. These specialized filters are typically referred to as “sulphur filters” or “carbon filters for sulphur removal.” They are specifically formulated with activated carbon optimized for adsorbing hydrogen sulphide molecules, ensuring effective odour elimination.

Equipment Involved in the Process

To implement activated carbon filtration for sulphur odour reduction, specific equipment is required. Here are the primary components involved:

Carbon Filter Housing

The carbon filter housing is a container that holds the activated carbon filter cartridge. It is designed to provide a secure and watertight environment for the filtration process. The housing is typically made of durable materials such as plastic or stainless steel, ensuring longevity and reliability.

Carbon Filter Cartridge

The carbon filter cartridge contains the activated carbon material responsible for adsorbing sulphur compounds. It is placed within the filter housing and serves as the primary element in the filtration system. The cartridge is replaceable and requires periodic replacement to maintain optimal performance.

Pre-filtration System (Optional)

In some cases, a pre-filtration system may be employed to remove larger particles and sediment from the water before it reaches the carbon filter. This additional step helps prolong the lifespan of the activated carbon filter cartridge, ensuring efficient operation over time.

Operating Parameters of Activated Carbon Filtration

To achieve the best results with activated carbon filtration, certain operating parameters should be considered:

Contact Time

The contact time refers to the duration that the water remains in contact with the activated carbon material within the filter cartridge. Sufficient contact time allows the carbon to effectively adsorb the sulphur compounds, ensuring optimal odour removal. The specific contact time required may vary depending on the flow rate and the manufacturer’s recommendations.

Flow Rate

The flow rate of water passing through the activated carbon filter affects the contact time and overall filtration efficiency. It is important to ensure that the flow rate falls within the recommended range specified by the filter manufacturer to maintain optimal performance.

Replacement Frequency

Activated carbon filters have a limited lifespan, and the filter cartridge needs to be replaced periodically. The replacement frequency varies depending on factors such as water quality, usage, and the specific carbon filter model. It is essential to follow the manufacturer’s guidelines and regularly replace the filter cartridge to sustain effective sulphur odour reduction.

3. Aeration with Birm Filter

Aeration involves exposing the water to air, oxidizing the Hydrogen Sulphide gas to a particle, dallowing the dissolved hydrogen sulphide gas to escape, and then filtering out the particles with Birm media.. This method is particularly useful when dealing with high concentrations of sulphur odour. Aeration systems should be installed at the point of entry. Introduction

In this article, we will explore the process of aeration and how it effectively reduces sulphur odours in households. Aeration involves exposing water to air, allowing dissolved hydrogen sulphide gas to escape, thereby eliminating the unpleasant smell. We will discuss the working principle of aeration, the equipment involved in the process, the operating parameters to consider, and provide insights into the extent of sulphur removal and the time required for the treatment.

Understanding Sulphur Odours

Aeration: How Does It Work?

Gas Exchange Mechanism

Aeration works on the principle of gas exchange. By exposing water to injected air, the dissolved hydrogen sulphide gas oxidizes into a particle, then the excess air is released into the atmosphere. As the water comes into contact with air, the hydrogen sulphide molecules present in the water transfer from the gas phase to the particle phase. This process allows the particles to be captured, and the excess air is released, resulting in the elimination of the sulphur and the odour.

Types of Aeration Systems

There are different types of aeration systems that can be used to reduce sulphur odours in households:

  1. Point-of-Entry (POE) Aeration Systems: These systems are installed at the point where water enters the house. POE aeration systems treat the entire water supply, ensuring that all taps and fixtures receive odour-free water.
  2. Point-of-Use (POU) Aeration Systems: POU aeration systems are installed at specific taps or fixtures, such as kitchen faucets or shower-heads. These systems provide targeted treatment for individual outlets, allowing flexibility in addressing specific odour issues.

Equipment Involved in the Process

To implement aeration for sulphur odour reduction, specific equipment is involved. Here are the primary components:

  1. Aeration Tank or Chamber: The aeration tank or chamber is designed to expose water to air, facilitating the gas exchange process. It allows sufficient contact time between the water and air to ensure effective odour removal. The tank or chamber is typically made of materials resistant to corrosion and is equipped with appropriate fittings for water inlet and outlet.
  2. Aerator or Air Diffuser: The aerator or air diffuser introduces air into the water, maximizing the contact between water and air. It is placed within the aeration tank or chamber and is designed to disperse air bubbles throughout the water, facilitating the release of dissolved hydrogen sulphide gas.
  3. Air Pump (Optional): In some cases, an air pump may be required to ensure sufficient oxidation through the aeration system. The air pump helps maintain a consistent water supply, ensuring efficient aeration and gas exchange.

Operating Parameters of Aeration Systems

To achieve optimal results with aeration, certain operating parameters should be considered:

  1. Contact Time: The contact time refers to the duration that the water remains in the aeration tank or chamber, allowing for effective gas exchange. Sufficient contact time ensures the release of dissolved hydrogen sulphide gas, resulting in odour reduction. The specific contact time required may vary depending on the system design and the severity of the odour issue.
  2. Air-to-Water Ratio: The air-to-water ratio represents the amount of air introduced into the water. It is an important parameter to consider as an appropriate ratio ensures efficient gas exchange. The ideal ratio depends on factors such as water quality, temperature and pH of the water.
  3. Water Flow rates: The Birm media requires sufficient water flow to backwash and clean the filter media inside of the tank. This flow rate almost always must exceed 5 gal/minute. More is better. And the larger the filter media in the tank, 1 cu ft., 2 cu ft., the higher the required flow rate.

4. Water Softeners and Catalytic Carbon Filters

In some cases, the presence of hydrogen sulphite gas is accompanied by hard water issues or excessive iron content. In this circumstance, the mineral content tends to hang onto the H2S odours after the treatment of the sulphur. Water softeners and catalytic carbon filters can be effective solutions in such situations. These systems not only remove the sulphur smell but also address other water quality issues, providing clean and fresh-tasting water.

Operational Requirements of the Equipment

To ensure the effectiveness and longevity of the equipment used to remove the sulphur smell, it’s essential to consider the following operational requirements:

Proper maintenance is crucial for the optimal functioning of any equipment involved in water treatment. Follow the manufacturer’s instructions.

AUTHOR’S NOTES: Although I understand the theory in this application, I do not recommend this approach. If you still have odour after pre-treatment for the sulphur, I suggest you run your cold water tap and smell only the cold water. If the smell is significantly less than on the hot side, removal of the magnesium anode rod in your hot water tank is the most likely culprit!

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