Can a Running Toilet Drive Up Water Bills in Multifamily Properties?

In large buildings and multifamily properties, unnoticed water waste can quickly escalate into significant operational costs. One of the most common and underestimated causes? A running toilet.

Though it may seem like a minor maintenance issue, a continuously running toilet can silently waste thousands of gallons of water per month. The result: unexpected spikes in utility bills and avoidable property expenses. In properties with dozens or hundreds of units, the financial impact multiplies.

Let’s break down how much water a running toilet can waste, why it often goes undetected, and how smart water submetering solutions like those provided by Mainlink can help you identify and stop leaks early.

How Much Can a Running Toilet Cost?

A running toilet continuously leaks water from the tank into the bowl, often without visible signs. So, can a running toilet cause a high water bills?

Here’s what the data shows:

Leak Size	Water Lost / Day	Estimated Daily Cost	Water Lost / Hour	Estimated Hourly Cost
Small Leak	~30 gallons	~$0.40	~1.25 gallons	~$0.02
Medium Leak	~250 gallons	~$3.30	~10.4 gallons	~$0.14
Large Leak	~4,000 gallons	~$53.00	~166 gallons	~$2.20

Rates vary across the U.S. from about $3 to $13 per 1,000 gallons. This table uses an average of $0.0132 per gallon, which reflects NYC prices.

Over the course of a month, a single large leak can cost up to $1,500. If this occurs in just 5% of units across your property, your losses could exceed tens of thousands of dollars annually without factoring in structural damage or repair costs. Many leaks are progressive and will worsen if they aren’t fixed promptly, so these already high costs could balloon far beyond manageable if not identified and fixed as soon as possible.

Why Do Toilet Leaks Often Go Unnoticed?

Toilet leaks are often silent and intermittent, especially in the early stages. Common causes include:

• Worn or misaligned flapper valves
• Float valve malfunctions
• Debris in the fill valve or seal wear

In many cases, residents are simply unaware of the issue. If a toilet keeps running randomly, it can be challenging to detect, especially if it occurs at night or when no one is home. Consistent problems are easier to spot, but by the time this happens, it’s likely the leak has been ongoing for quite some time and the water bill reflects it. Manual inspections are time-consuming and inconsistent, and relying on water bills to spot anomalies is often too late.

Manual Leak Detection: Useful But Not Enough at Scale

Household leak detection methods include:

• Listening for running water – A subtle but continuous sound in the tank may signal a leak.
• Dye test – Add a few drops of food coloring to the tank. If it appears in the bowl without flushing, there’s a leak.

While effective in single-family homes, these methods don’t scale across multifamily buildings. They require tenant cooperation or staff inspection of each unit – an inefficient, reactive approach that delays resolution and increases cost.

Detecting Toilet Leaks Before They Become Losses

Let’s take a look at a practical scenario to understand the cost impact of failing to detect toilet leaks before they progress to losses.

Imagine a 50-unit property with five floors. If just one running toilet goes undetected per floor, each leaking approximately medium amount –  250 gallons per day, this results in:

• 1,250 gallons lost per day
• Approximately $21 per day in water and sewer costs (based on NYC rates, in each state water prices are different)
• Around $630 in monthly losses
• 37,500 gallons per month wasted – enough to fill two average backyard swimming pools

This example shows just how damaging a leaky toilet water bill can be, especially if detection is built on guesswork and inefficient manual monitoring.

With Mainlink, you don’t have to guess. Our system automatically detects abnormal usage, sends real-time alerts, and helps you take action before minor issues turn into major expenses.

Why Smart Water Submetering Is the Better Solution

Smart water meters with automatic leak detection are among the most cost-effective solutions for identifying leaks – whether in a toilet or anywhere else in the water system. They replace labor-intensive manual checks with automated monitoring and deliver unprecedented visibility into water usage. They can be very effective at scale, allowing automatic leak detection, data collection, and meter readings across a large property or mobile home park.

Mainlink’s smart water submetering system makes leak detection proactive and scalable. Our solution includes:

• NTEP-certified ultrasonic water meters – High-precision, non-invasive metering with no moving parts
• Built-in leak detection – Captures even the smallest anomalies in flow
• Real-time alerts – Immediate notifications via mobile application and email
• NTEP-Certified resident-facing app – Tenants can monitor usage and receive leak alerts
• Data management platform – Full visibility across every unit, without remote displays or repeaters

This setup results in fewer service calls, reduced operational risk, and tighter control over property-wide water costs.

The Axioma Ultrasonic Water Meter: Built for Multifamily Monitoring

Developed by Axioma Metering and integrated into Mainlink’s platform, the Axioma Ultrasonic Smart Water Meter is built for:

• All-weather installations – IP68-rated for indoor and outdoor use
• Multi-unit applications – Ideal for multifamily buildings, RV parks, and manufactured housing
• Hardware reduction – No need for repeaters, displays, or extra transmitters
• Analytics-ready data – Connected to the Mainlink data management platform for detailed reporting and alerting

Together, this system gives you full, unit-level visibility while simplifying the entire infrastructure. 

Final Thoughts

 single running toilet can become an expensive, hidden liability. In large properties or portfolios, this issue quickly scales – potentially costing thousands of dollars each month. But with Mainlink’s smart metering solution, you gain full control and early visibility protecting both your budget and your buildings. 

Stop relying on delayed bills and manual inspections to identify your leaky toilets. Upgrade to almost real-time monitoring, instant leak alerts, and a smarter way to manage water. Contact us today to learn more about our resource-saving solution.