How Condensate Neutralizers Can Protect Your Plumbing System

Condensing water heaters, such as tankless brands from Rinnai, Noritz, and Navien, are highly favoured by homeowners due to their energy-saving and eco-friendly features, resulting in lower energy bills and healthier environment.

But there’s a little secret about them: they produce something called acidic condensate. Think of it as a kind of sour water.


Now, why should you care? Well, if this condensate isn’t handled correctly, it can harm your home plumbing and even the environment outside. We don’t want leaky pipes or to harm nature, right?

The good news is there’s a solution. We can use a condensate neutralizer to neutralize this acidic water, making it safe. By doing this, you’re not only taking care of your home’s plumbing but also doing a good deed for our planet. It’s like getting the best of both worlds: a cozy, warm home and a clean, green backyard.

Are Condensate Neutralizers Required?

Whether condensate neutralizers are required for tankless water heaters or any other device largely depends on the design of the device, the local building and plumbing codes, and the specific recommendations of the equipment manufacturer.

Let’s explore the details of when, why, and in which situations you might require one.

What Causes Condensation in Water Heaters and How Much Is Produced?

In condensing boilers and water heaters, condensate forms when water vapor in the flue gas cools and turns into a liquid. This process is termed “condensation,” and it starts when the flue gas temperature drops below the “dew point.”

The common dew point for natural gas combustion is around 135°F (57°C).

The presence of condensation signifies that the appliance operates efficiently, capturing heat from the flue gases effectively. When in minimal quantities, it’s not harmful.

However, in non-condensing appliances, a considerable amount of the water vapor, along with the heat it carries, gets released through the flue, making the water heating process less efficient.

For ultra-efficient heaters, it’s essential to be aware that the produced condensate needs to be properly managed and neutralized.

The volume of the generated condensate is directly related to the amount of fuel they burn and their operational efficiency.

A general guideline suggests:

For every 100,000 BTU of natural gas or propane (LPG) combusted in a high-efficiency water heater, roughly one gallon of condensate is generated. This amount can fluctuate depending on the unit’s design, efficiency, and the fuel type.


Should a condensing water heater have an input rating of 200,000 BTU/hr and it operates for 5 hours, it will utilize 1,000,000 BTU of gas. Based on the provided guideline: 1,000,000 BTU ÷ 100,000 BTU/gallon equates to 10 gallons of condensate in those 5 hours.

Why Is Condensate Acidic?

Condensing water heaters are designed to extract as much heat as possible from combustion gases, resulting in the formation of condensate, a mildly acidic water.

This acidity arises due to the interaction of these gases, primarily carbon dioxide, with water, forming carbonic acid. To understand the potential harm of this condensate, it’s important to be familiar with pH levels: a lower pH indicates higher acidity, and condensate typically has a pH between 3 and 4.

Importance of Neutralizing Condensate

Neutralizing condensate is essential for homeowners with high-efficiency appliances. Understanding its importance ensures the following:

Protection of Plumbing Systems: Acidic condensate can corrode metal pipes, drains, and other plumbing components over time. This can lead to leaks, water damage, and potentially costly repairs. By neutralizing the condensate, homeowners protect their plumbing infrastructure and prevent unforeseen expenses.

Environmental Considerations: Releasing acidic condensate into the environment can harm aquatic life and alter the pH of natural water sources. Neutralizing condensate helps homeowners reduce their environmental footprint.

Municipal Regulations: Many municipalities have regulations regarding the disposal of acidic wastewater. Homeowners might face penalties or fines if they discharge untreated condensate into public drainage systems.

Options for Condensate Neutralization: Where Do You Drain Condensate From a Tankless Water Heater?

Neutralizing acidic condensate is crucial for preserving plumbing systems and adhering to environmental guidelines, and it can be achieved through various methods, each tailored to specific needs:

  • Natural Ground Integration: Homeowners can create a bed of limestone directly in the floor where equipment like condensing water heaters or boilers are installed. The condensate can then naturally drip onto this limestone bed, neutralizing the acidity on contact.
  • Internal Neutralization Cartridges: Within the condensing unit, cartridges filled with limestone can be positioned. These cartridges allow the condensate to flow through them, neutralizing its acidity as it passes internally within the appliance.
  • External Neutralization Kits: An external approach involves attaching a neutralization kit to the condensing equipment. This kit, in essence, is a pipe segment loaded with limestone. As condensate exits the appliance, it flows through this limestone-filled pipe, undergoing neutralization before its eventual discharge.
  • Neutralization Tanks: These are tanks filled with alkaline media (like limestone chips) that neutralize the acid in the condensate. The condensate flows through the media, increasing its pH before it’s discharged.

How Does a Condensate Neutralizer Work?

A condensate neutralizer works by passing the acidic condensate over a medium (usually utilizing a pump), typically composed of alkaline materials like calcium carbonate (limestone) chips, marble, or magnesia.

As the acidic condensate flows over this medium, the acid reacts with the alkaline materials, raising the pH level of the condensate and effectively neutralizing its acidity.

Once neutralized, the condensate is safer for discharge into drains, sewer systems, or the ground without causing damage or posing environmental risks.

Consequences of Improper or Lack of Neutralization

Improper or lack of neutralization of the acidic condensate produced by high-efficiency appliances can result in several negative consequences:

  • Corrosion of Plumbing Systems: Acidic condensate can aggressively corrode metal pipes, fittings, and drains. This can lead to premature wear and tear, potentially causing leaks and water damage.
  • Damage to Wastewater Infrastructure: Municipal wastewater systems are not typically designed to handle highly acidic wastewater. Over time, untreated acidic condensate can corrode and damage public sewage infrastructure.
  • Environmental Impact: Discharging acidic condensate into the environment without neutralizing it first can harm aquatic ecosystems by reducing the pH of water sources. This can negatively affect aquatic life and the overall health of rivers and lakes.
  • Potential Fines and Penalties: Many municipalities and jurisdictions have regulations and standards related to the pH levels of wastewater. Discharging untreated or improperly treated condensate could result in violations, leading to potential fines or penalties.
  • Soil Degradation: If acidic condensate is discharged directly onto the ground or into a septic system, it can lead to soil acidification, affecting plant health and potentially contaminating groundwater.
  • Reduced Equipment Lifespan: The corrosive nature of acidic condensate can reduce the lifespan of the equipment it comes into contact with, including pumps and other components.
  • Health Concerns: In rare cases, if the condensate seeps into drinking water sources, it could pose a health risk due to the change in water pH and potential contaminants.

The International Plumbing Codes (IPC) and National Standard Plumbing Codes (NSPC) emphasize the critical need for neutralizing corrosive waste. Both these codes stipulate that harmful chemicals and corrosive liquids, which can jeopardize plumbing systems or emit harmful fumes, must undergo neutralization or treatment before being introduced into the plumbing framework.

While the NSPC is primarily designed to guarantee the correct installation of plumbing systems, the IPC offers a comprehensive set of regulations to protect the health and safety of building occupants in relation to plumbing systems and components.


Being a responsible homeowner means understanding and addressing the needs of every appliance in the home. When it comes to condensing water heaters, using a condensate neutralizer and ensuring proper neutralization of condensate is vital not just for the health of the plumbing system, but also for the environment.

As you enjoy the benefits of your energy-efficient water heater, take a moment to ensure you’ve taken steps to neutralize its acidic by-product, safeguarding your home and nature.


How Can You Tell the Difference Between a Water Heater Leak and Condensation?

Distinguishing between a water heater leak and condensation involves examining the amount, location, and temperature of the moisture:
Condensation typically forms as light moisture on the water heater’s outer surface or cold-water pipes. It might reduce as the heater warms up and is often seen when the heater’s exterior is cooler than the surrounding air.
Leaks produce more consistent pooling, often originating from the water heater’s base, relief valves, or connections. Leaks will be persistent over time, and the water is typically warm or hot to touch.

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