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6 Reasons Why Toilets Tend To Leak

Residential toilets are one of the most common culprits for water waste in homes and apartments. Leaks in toilets sometimes go unnoticed until the damage is obvious – high water bills from water waste and damage to property from leaking water.

Homeowners and property owners should know what causes toilet leaks so that they can find and fix them before they cause major problems. When toilet leaks are not addressed promptly, the headaches and costs can skyrocket. 

In this article, we'll talk about the importance of finding a toilet leak, the causes, the financial impact,  and ways to prevent it.

Importance of Finding a Toilet Leak

Finding a toilet leak as early as possible is important for several reasons.

First, leaks waste water, which is bad for the environment and can lead to a huge spike in water bills, even if the leak is small. 

Second, if leaks are not found and fixed, they can cause much bigger problems later on, like rotting floors and walls. This can lead to mold and mildew. Aside from causing health risks to residents, these problems can cost a fortune to fix.

Finding and fixing toilet leaks right away keeps homes and buildings safe, prevents damage, and saves water.

Anatomy of a Toilet 101

How a toilet works isn’t something most people spend much time thinking about, but it is important to understand how leaks can arise and what to do about them. Welcome to Anatomy of a Toilet 101! Don’t worry, it’s a lot easier than med school.

Basic Components


  • The tank holds water needed for flushing.

  • The flush valve mechanism and refill mechanism are inside the tank and regulate the flow of water into and out of the tank.


  • The toilet bowl receives waste (to put it politely). When the toilet is flushed, water flows from the tank to the bowl to wash the waste down the drain.

  • The bowl is designed to direct waste into the sewer system efficiently.

  • The bowl sits on a wax ring that seals the joint between the bowl and floor. This prevents leaks from the bowl drain onto the floor. 

Flush Mechanism

  • The flush mechanism consists of a handle a chain, and a toilet flapper valve at the bottom of the tank. The chain connects the handle to the flapper valve, so that when the handle is pressed, the flapper valve opens.

  • The mechanism is activated by the user to release water from the tank into the bowl.

Refill Mechanism

  • The refill mechanism consists of a fill valve and a float.

  • The refill mechanism regulates the refilling of the tank with water after flushing and shutting off when the water reaches a certain level.

white toilet anatomy

How Toilets Work

All of the components of a toilet need to be functioning properly. If any of these components wear out or break, serious problems can arise.

  • The Flushing Process

The flushing process begins with pressing the flush handle, which pulls on the chain and lifts the flapper valve at the bottom of the tank.

When the flapper valve opens, water rushes from the tank into the bowl, creating a siphon effect that pulls waste from the bowl into the sewer line.

  • Refilling the Tank

When the tank empties after flushing, the refill mechanism is activated.

The refill valve opens and allows water to enter the tank from the water line. The float rises with the water level in the tank. Once the float reaches its set height, it closes the fill valve and stops the water flow.

  • The Role of Seals and Gaskets

Seals and gaskets ensure water tightness between the tank and bowl and within the toilet flushing mechanism.

They prevent water leaks from the tank into the bowl (when not flushing) and external leaks.

6 Reasons Why Toilets Tend to Leak

1. Flapper Valve Deterioration

The flapper valve is important for maintaining water within the toilet tank. Over time, it can wear out due to chemicals in the water, cleaning agents, or simply through regular use. 

A deteriorated toilet flapper often does not seal properly. This allows water to continuously flow from the tank into the bowl. As the tank empties, the float lowers and opens the fill valve to refill the tank. Then the process repeats. 

Although such a leak may seem small, it can quickly add up to hundreds or thousands of dollars on your water bills.

2. Worn-Out Fill Valve

A faulty fill valve can cause continuous water flow into the toilet tank, sometimes leading to overflow into the toilet bowl. 

This malfunction is typically due to natural wear or buildup of minerals from the water, necessitating its replacement to prevent water wastage and potential overflow damage.

This continuous water flow may seem small, but the costs can add up quickly.

3. Faulty Wax Seal

The wax seal under the toilet ensures a watertight connection between the toilet and the drain pipe. However, after a while, this seal can break down due to the toilet's movement or changes in the floor, leading to leaks at the base of the toilet. 

Such leaks can damage the floor and require urgent repair to prevent structural damage.

4. Cracks in the Tank or Bowl

Over time, impacts, temperature changes, or manufacturing defects can cause a cracked toilet tank or bowl to develop in the toilet's porcelain. 

Even small cracks can lead to significant water leaks, either internally within the tank or externally, potentially causing water damage to the bathroom floor and necessitating costly repairs or replacement.

5. Loose Connections or Faulty Gaskets

The integrity of connections between the tank and bowl or at the water supply line is important for a leak-free toilet. 

Loose connections or degraded gaskets can result in leaks at these junctions. Regular maintenance and tightening can help prevent such issues.

6. Corrosion or Damage to the Supply Line

The supply line, which delivers water to the toilet, is susceptible to corrosion or physical damage over time. 

This deterioration can lead to leaks, either at the connection points or along the line itself, potentially causing water damage and necessitating a replacement of the line.

a plumber fixing a toilet

How to Stop the Toilet From Leaking?

  1. Replace the Flapper Valve: Often the culprit behind leaking toilets, a worn-out flapper valve can be easily replaced. Ensure you choose the correct size and material compatible with your toilet model to create a watertight seal in the tank.

  2. Fix or Replace the Fill Valve: A malfunctioning fill valve can lead to continuous water flow or tank overflows. Adjusting or replacing the fill valve can prevent water waste and stop the toilet from leaking.

  3. Replace the Wax Seal: If the leak originates from the base of the toilet, replacing the wax seal can fix the issue. This task might require removing the toilet, cleaning the old wax, and setting a new seal before reinstalling the toilet.

  4. Repair Cracks in the Tank or Bowl: Small cracks can sometimes be repaired with waterproof silicone or a porcelain repair kit. However, significant damage typically requires replacing the affected part or the entire toilet.

  5. Tighten Loose Connections: Check all the connections between the tank, bowl, and water supply line. Tighten any loose bolts or nuts, and replace worn-out gaskets or washers to ensure a leak-free seal. But be careful not to overtighten. 

  6. Replace the Supply Line: If the supply line is corroded or damaged, replacing it can prevent leaks. Use a high-quality, flexible supply line for ease of installation and long-term reliability.

  7. Regular Maintenance: Conduct regular inspections of your toilet's components, looking for signs of wear or damage. Promptly addressing any issues can prevent leaks from developing or worsening.

  8. Professional Plumbing Inspection: For persistent or complex leaks, seeking the help of a professional plumber can ensure a thorough inspection and repair. 

Why Submetering is Your Best Choice

Our case study clearly illustrates the potential financial and environmental benefits of submetering specific appliances within a property. Submetering at the fixture level is different from submetering an entire apartment unit on the water main.

It requires a very small device called a micrometer that is easy to install and reliably measures water flow.

In this instance, the focus is on submetering only the toilets in a building with 12 apartment units. The data presents a significant reduction in water usage and, consequently, substantial savings for the property owner. 

Let's analyze the impact and implications:

DrizzleX case study

Environmental Impact

Installing micrometers on the toilets in this building resulted in an impressive reduction of over 2,000 gallons per day on average. This added up to to over 750,000 gallons saved per year. 

This significant reduction in water usage not only helps conserve a critical natural resource but also demonstrates how targeted interventions can lead to substantial environmental benefits.

Financial Impact

The annual cost savings attributed to the reduction in water usage amount to $13,794 The building’s water bills were reduced by more than 60%.

This figure illustrates the economic advantage of implementing submetering systems for property owners, providing a strong incentive beyond the environmental impact.


Savings Calculation: Water usage savings translate directly into financial savings, emphasizing the efficiency of submetering systems in reducing unnecessary water consumption. This is particularly relevant for toilets, which are among the highest water-using fixtures in residential units.

Scalability: The data from this case study suggest that scaling the application of submetering systems to include other high-usage appliances or fixtures could further increase savings. This could include showers, sinks, and laundry facilities, among others.

How DrizzleX Can Help You

DrizzleX home page

DrizzleX allows you to detect hidden leaks, such as running toilets and leaky faucets, to stop millions of gallons of waste each year. It also alerts you to excessive water overuse by tenants. Typically, buildings that use DrizzleX reduce their water bills by 20-40% or more.

And you can expect a pretty quick return on investment (ROI). Buildings with DrizzleX save enough water to cover the entire cost of DrizzleX within about 9 months on average.

Usage Reports

One of DrizzleX's solutions is the "Tenant's Overuse" report. Since many people aren't really aware of their excessive water usage, an accurate report can be very helpful in preventing unnecessary expenses.

Using the reports, you can communicate with your tenants about their water consumption habits and back them up with precise data.

Leak Detection

Leaks can be sneaky because they aren't always visible. With property inspection, you can see the obvious ones. But silent leaks will only show up on your utility bills. DrizzleX gives you water control because you can monitor the water flow in your building.

The system will notify you about where and how much water is being lost.

E-mail Notifications

Once DrizzleX spots the leak, it will notify you via email. The message you receive will include all the details about the exact apartment and fixture that is the culprit, how many gallons were used, how much it will cost you if the problem isn't fixed, and even possible causes for the water waste and how to fix it.


DrizzleX also allows you to bill your tenants. Tenants conserve water when they are the ones paying for it. You can easily create water bills based on accurate water consumption and bill them fairly.

FAQs About Why Toilets Tend to Leak

Why does a leaky toilet often go unnoticed?

A leaky toilet may not make a lot of noise or show visible signs until the issue becomes significant, making it easy to overlook.

What are the common causes of a toilet leaking?

Common reasons for a toilet leaking include worn-out flapper valves, damaged seals, or issues with the toilet's internal tank components.

How can I prevent my toilet from leaking?

Regular maintenance, such as checking the flapper valve, the seal, and the condition of the tank's internal parts, can prevent your toilet from leaking.



Take control of your water usage and save money with our submetering system.

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