Toilet Failure Risks

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A review by the Insurance Institute for Business & Home Safety of homeowners’ insurance claims resulting from toilet failures submitted by multiple insurance companies around the country revealed:

  • Toilet failures are the second leading source of residential water losses, after plumbing supply line failures.

  • 78% of all toilet failures were caused by faulty supply lines, toilet flanges, fill valve assemblies or toilets that have backed up and overflowed.

  • Toilet failures cost an average of $5,584 per incident, after the deductible was paid.

  • Slow leaks resulting from faulty drain lines and toilet flanges (wax seals) generally result in less severe claims than those caused by the sudden failures of supply lines, fill valves, overflows and a cracked tank or bowl.

  • Newer homes are more likely to have a water loss caused by a sudden failure, which results in more severe damage.

  • Older homes are more likely to experience a water loss due to a slow and seeping failure. The loss severity decreases as the home ages.

  • Toilet failures on the first floor resulted in more severe claims than those in basements or on upper floors.

  • Approximately 14% of all toilet failures occurred in unoccupied homes.

Toilet Failure Mode Claim Frequency and Severity:

In a review of 1,304 toilet failures resulting in a claim, one-third were caused by an overflowing or backed up toilet. (See Figure 1Figure 1) A claim was categorized as a “backup/overflow” when the adjuster noted that the toilet overflowed, but the exact cause could not be determined. Many of these overflows/backups may be due to faulty fill valves or clogged drain lines.

Figure 1: Toilet Failure Mode Claim Frequency

Faulty supply lines, fill valves and toilet flanges (wax seals) accounted for a combined 45% of all toilet failures resulting in a claim.

The cost of a toilet failure can vary greatly depending on the cause. Generally, failures resulting in slow, seeping leaks will cause less severe losses than a sudden burst or overflow from a water source under pressure. Faulty drain lines and toilet flanges were more likely to result in slow, seeping leaks than the other loss sources.

Damage resulting from water losses due to toilet failure varied from just over $2,000 to more than $10,000 per incident. (See Figure 2Figure 2) Supply line failures resulted in 59% greater losses than the next leading cause.

Figure 2: Toilet Failure Mode Claim Severity

There was a significant difference in the severity of claims resulting from drain line and seal/flange failures compared to the other causes. There also was a significant difference between losses caused by the failure of supply lines as compared to other sources. However, there was no significant difference between a cracked toilet tank or bowl and fill-valve failures.

Loss Source

Lower Quartile

Upper Quartile

Inter-Quartile Range





Drain line








Fill Valve




Cracked Bowl/Tank




Supply Line




Table 1: Interquartile Range of Claim Payments by Toilet Failure Mode

The interquartile range defines the upper and lower boundary limits for which the middle 50% of all claim payments fall. Here, it illustrates here how the cost of a claim resulting from toilet failure can vary depending upon the loss source. (See Table 1Table 1)

Toilet Failures and Home Age:

In this study, the percentage of a water claim due to a toilet failure decreased as the home aged. (See Figure 3)

Figure 3: Percentage of Water Claims Due to Toilet Failures by Age of Home

More than 14% of all water claims resulted from toilet failures in newer homes less than 10 years old, as compared to an average of just 9% of all water claims in homes 40 years old and older.

The frequency of the individual causes of toilet failures resulting in a claim was examined. The causes were categorized as “slow failures,” for those resulting from failed drain lines and faulty toilet seals/flanges, and “sudden failures,” which represented all other loss sources. The age of the home for each of these two types of failures also was analyzed.

“Slow failures” due to faulty drain lines or toilet seal/flanges, which produced significantly less severe claims, were far more common in homes older than 60 years. (See Figure 4) By contrast, homes less than 60 years of age, were more likely to experience water losses due to sudden toilet failure modes, which typically cause greater damage and lead to more severe claims.

Figure 4: Frequency of Toilet Failure Types by Age of Home

Toilet Locations in the Home:

The severity of water damage resulting from a toilet failure varied by location. The most severe damage involved toilets located on the first floor of a home. (See Figure 5)

Figure 5: Toilet Claim Severity by the Location of the Toilet in the Home

There was a significant difference in the severity of losses based on the location of the toilet. Failures on the first floor resulted in approximately 50% higher claims than those involving toilets located in basements or on upper floors. First floor bathrooms are commonly located off central living spaces, such as living rooms and kitchens, which contain expensive furniture, kitchen cabinetry, electronics and hardwood flooring. While this type of exposure is also possible on upper floors, it is not as common. Further, if the toilet is located in the basement, damages can be minimized if the basement is not finished or by the presence of floor drains and sump pumps. There were no statistically significant differences in the costs associated with toilets that failed in basements or on upper floors.

The average severity of claims resulting from first floor toilet failures was calculated for those that occurred in homes with no basement on a slab foundation and for those homes with a finished, partially finished, or unfinished basement. The results revealed no significant difference in the severity of claims resulting from water losses on the first floor regardless of whether the home had a finished basement or a slab foundation. There were too few claims with partially finished and unfinished basements to determine whether these basement types had any effect on the claim severity. The basement type was known for 40% of all toilet claims reviewed in this study.

The study results also showed a disparity between the frequency of various causes of toilet failures located in the basement, first floor and upper floor levels. (See Figure 6)

A backed up or overflowing toilet was the cause of 58% of failures resulting in a claim in a basement, compared to the overall average frequency of 33% for all areas of the home. This may be due to the fact that basements toilets are installed below grade, making it more difficult to obtain the proper slope needed to reach the main sewer line.

Figure 6: Toilet Failure Mode Distribution by Toilet Location

Plumbing that does not achieve the required slope of ¼-inch per foot may not adequately drain. As a result, over time, solids can build up in the pipe and cause the toilet to back up and overflow. Since toilet backups/overflows are one of the less severe failure modes, this also explains why toilet failures in the basement are not as severe as those that occur in other locations.

Faulty supply lines were the most frequent cause of water losses resulting from toilet failures on a home’s first floor. This accounts for the increased severity of losses in this location since supply line failures are among the most costly.

Reducing Toilet Failure Risk

The most basic way to prevent water damage caused by a failing toilet is to remain in or near the bathroom until the valve has finished refilling the tank and bowl. Here are some steps to take at the first sign of failure:

To prevent tank overflow:

  • Lift off the top of the tank and lift up on the float valve.

  • While continuing to hold the float, shut off the supply valve. This valve is usually located on the wall or the floor near the toilet.

For a clogged toilet:

  • Lift off the top of the tank and make sure the flush valve is closed.

  • Do not continue to flush the toilet if it appears clogged. Use a toilet plunger or snake to clear the clog.

If a toilet is prone to clogging:

  • Consider flushing a second time once the toilet has stopped running.

  • This can help to remove solids from the drain pipe.

  • More serious toilet backups or overflows may require a professional plumbing service to clear the drain line.

Consider the following features when selecting a new toilet:

  • A 3-inch or greater gravity flush valve, the hole at the bottom of the tank leading to the toilet bowl, instead of the standard 2-inch. Or choose one of the newer toilet flushing technologies, such as a pressure-assisted flush valve.

  • A 2-inch or larger diameter glazed trapway, the hole at the bottom of the toilet bowl, instead of the standard 1 7/8-inch diameter. This can reduce friction and the potential for clogging.

Proper maintenance is the first step in preventing toilet failure:

  • Inspect the components inside their toilet every six months.

  • Remove the top of the toilet tank.

  • Flush the toilet and examine the operation of the internal tank components.

  • Is the fill valve operating properly?

  • Is the flush valve secure over the opening at the bottom of the tank?

  • Water running periodically in a toilet tank between uses is a sign that your internal tank components are beginning to fail. The most common problem is a leaking flush valve.

  • Periodically check the supply line connection to ensure that it is not loose.

  • Close and open the supply valve to the toilet twice a year. It should turn smoothly and should not have signs of rust, which could cause it to lock in position.

Inspecting for a slow leak:

  • Add a few drops of food coloring to the water in the toilet tank.

  • Allow the toilet to sit for a period of time without flushing it.

  • If you eventually notice colored water in your bowl, you have a leak.

  • Other indications include red streaks on the side of your bowl. These occur from mineral deposits left over from a constant stream of water.

  • Check the toilet base and supply line for signs of leaking.

  • If you have toilets on upper floors, inspect the ceiling directly below for signs of discoloration.

Important notes about this claim study:

1) This study includes the analysis of 1,304 toilet claims from a sample of 12,404 closed water claims. These claims occurred in 20 different states from five insurance companies.

2) Where analyses were conducted on the severity of toilet claims, only 11,377 closed claims and 1,134 toilet claims were considered. The remaining claims were removed from the sample as the claims had obvious upper and lower claim payment limits placed on the claim sample pulled.

3) All claim severity analyses excluded any claim payment values that were more than three standard deviations greater than the average claim payment. These claims were termed “outliers”.

4) All statements in this study related to average claim payments have been tested for significance using a one-way ANOVA and Levene’s test for homogeneity of variance. Where homogeneity of variance was not met, Brown-Forsythe and Welch statistics were used to validate the significance.

5) Where equal variances were assumed, Scheffe’s Post Hoc test was used to determine underlying variances between specific groups of claims. Where equal variances were not assumed, the Games-Howell Post Hoc test was used.


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