Water Loss Due to a Leak
Please read before use
All figures in this calculator are examples and estimates and are provided solely as a basis for calculation. This applies to water volumes, runtime, and monetary amounts, as well as to savings, payback periods, and results over several years. Actual values depend on the specific network, prices, and local conditions and may vary significantly. This calculator is not a substitute for leak detection, planning, or a quote. Binding figures are available only upon request. Your data is processed anonymously on our server only and is not shared with third parties.
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One bar less—that is, instead of bar—reduces the loss by m³ per year. That is percent.
A reduction of 10 psi—that is, instead of psi—reduces the loss by gallons per year. That is percent.
Optional. Temperature affects the result by only a fraction of a percent.
Cold or hot water? This is the only case where the specification actually makes a difference. If there’s a leak in a hot water pipe at 60 °C, the result differs by 0.8 percent; at 80 °C, by about 1.3 percent. For cold drinking water, however, it’s not worth entering this information: The difference between the coldest winter value and the warmest summer value is only 0.09 percent—so for a 1-mm leak, that’s 1,330.5 versus 1,331.6 liters per day, or 0.4 m³ per year.
Cold or hot water? This is the only case where the specification actually makes a difference. For a leak in a hot water pipe at 140 °F, the result differs by 0.8 percent; at 176 °F, by about 1.3 percent. For cold drinking water, however, it’s not worth specifying the temperature: even between 40 and 80 °F, the difference is only 0.17 percent.
Guidelines for Germany The temperature of drinking water in the ground is usually between 5 and 8 °C in winter and between 14 and 20 °C in summer. These are rough guidelines, not fixed values: The actual temperature depends on the depth at which the pipe is buried, the soil type, the region, and the volume of water flowing through the pipe. House connections laid close to the surface and pipe ends with low flow rates tend to be closer to the ground temperature than a main line with high flow. If you do not know the exact value, use the annual average of about 12 °C.
Guidelines The temperature in the pipeline follows the ground temperature and varies greatly across the United States depending on the region. It also depends on the depth at which the pipe is buried, the type of soil, and the amount of water flowing through the pipe. Shallowly buried service lines and pipe ends with low flow rates tend to be closer to ground temperature than a main line with high flow rates. If you do not know the exact value, use approximately 54 °F. This will hardly affect the result.
Guidelines The temperature in the system follows the ground temperature. It depends on the burial depth, the soil type, the region, and the amount of water flowing through the pipe. Shallowly buried service connections and pipe ends with low flow rates tend to be closer to ground temperature than a main line with high flow. If you do not know the exact value, assume approximately 12 °C. This will hardly affect the result.
Why is that, anyway? Temperature affects the flow through its effect on density. Warm water is less dense, so it has less mass to accelerate and flows out slightly faster at the same pressure. Although viscosity changes much more significantly with temperature, it has no effect here: The flow through the hole is clearly turbulent at Reynolds numbers above 20,000, and at those levels, the discharge rate is practically independent of viscosity.
For Context A flow rate of 0.50 instead of 0.62 changes the result by 19 percent; a pressure of 4 bar instead of 5 bar changes it by 11 percent. The temperature is negligible compared to these variables. If the checkbox is unchecked, the calculator uses 998 kg/m³, which corresponds to approximately 20 °C.
For Context A flow rate of 0.50 instead of 0.62 changes the result by 19 percent; a pressure of 60 instead of 70 psi changes it by 7 percent. Temperature is negligible compared to these variables. If the checkbox is unchecked, the calculator uses 62.3 lb/ft³, which corresponds to approximately 68 °F.
as many as a small village with 250 to 500 residents
as much as a medium-sized village with 500 to 1,000 residents
as large as a large village with 1,000 to 2,000 residents
as large as a town with 2,000 to 5,000 residents
as large as a small town with a population of 5,000 to 20,000
as large as a medium-sized city with a population of 20,000 to 100,000
as much as a large city with a population of 100,000 to 1 million
as large as a metropolis with a population of 1 to 10 million
as many as a megacity with more than 10 million residents
That's about times the daily needs of Arnis an der Schlei (Germany's smallest town), which has about 280 residents.
That is about times the daily energy needs of the North Sea island of Spiekeroog, which has a population of about 800.
That is about times the daily consumption of Helgoland, which has a population of around 1,450.
That is about times the daily demand of Baunach in Upper Franconia (where SebaKMT is headquartered), which has a population of about 4,100.
That is about times the daily consumption of Rothenburg ob der Tauber, which has a population of about 11,000.
That is about times the daily demand of Bamberg, which has a population of around 79,000.
That's about times the daily demand of Nuremberg, which has a population of around 530,000.
That is about times the daily demand of Hamburg, which has a population of about 1.9 million.
That is about times the daily demand of Tokyo, which has a population of about 14 million.
That is about percent of the daily needs of Arnis an der Schlei (Germany's smallest town), which has about 280 residents.
That amounts to about percent of the daily energy needs of the North Sea island of Spiekeroog, which has a population of about 800.
That amounts to about percent of the daily energy needs of Heligoland, which has a population of about 1,450.
That is about percent of the daily energy needs of Baunach in Upper Franconia (where SebaKMT is headquartered), which has a population of about 4,100.
That is about percent of the daily demand in Rothenburg ob der Tauber, which has a population of approximately 11,000.
That amounts to about percent of the daily demand in Bamberg, which has a population of approximately 79,000.
That amounts to about percent of the daily demand in Nuremberg, which has a population of approximately 530,000.
That amounts to about percent of the daily demand in Hamburg, which has a population of approximately 1.9 million.
That is about percent of the daily demand in Tokyo, which has a population of about 14 million.
- Small Village Arnis
- Middle Village Spiekeroog
- Large Village Helgoland
- Large Congregation Baunach
- Small town Rothenburg
- Mittelstadt Bamberg
- Major city Nuremberg
- Metropolis Hamburg
- Megacity Tokyo
That's roughly equivalent to a household with two adults and one child.
That is equivalent to about households, each with two adults and one child.
Based on a daily requirement of 125 liters per person. Children count as adults.
Based on a daily requirement of 82 gallons per person (EPA). Children count as adults.
Based on a daily consumption of 140 liters per person (Ofwat). Children are counted the same as adults.
- per day
- 1,332 litersgallons 1.33 m³kgal 6.97 €
- per week
- 9,322 litersgallons 9.32 m³kgal 48.76 €
- per month
- 40,508 litersgallons 40.51 m³kgal 211.86 €
- per year
- 486,097 litersgallons 486.10 m³kgal 2,542.29 €
Annual Cost
- Drinking Water Award
- 865,25 €
- Working Price for Wastewater
- 1.677,03 €
- Additional costs due to the leak
- 2.542,29 €
- Base price remains unchanged
- 7.500,00 €
The base price does not depend on the quantity and does not increase due to the leak. It is included here solely to provide context for the total amount.
Here's how much you'll save once the leak is fixed
The lost water still has to be collected, treated, and pumped through the system. It just never reaches any customers. The electricity used for this is wasted. As soon as the leak is sealed, both of these costs are eliminated.
- That much electricity will no longer be consumed each year
- 243 kWh
- That much CO₂ won't be produced each year anymore
- 84 kglb
Here’s how it’s calculated: 0.5 kilowatt-hours of electricity per cubic meter of water and 344 grams of CO₂ per kilowatt-hour. The first value is the average for the German water supply. Depending on the terrain and treatment methods, it ranges from about 0.2 to 0.8, so it can be adjusted accordingly. The second value is the German electricity mix for 2025, according to data from the Federal Environment Agency.
Here's how it's calculated: 2.3 kilowatt-hours of electricity per 1,000 gallons of water and 767 pounds of CO₂ per megawatt-hour. The first value is the average from a survey of U.S. water utilities conducted by ACEEE and NAWC. It varies significantly depending on the terrain and treatment process, so it can be adjusted upward. The second value is the average of the U.S. electricity mix according to the EPA’s eGRID 2023. Regionally, it ranges from about 240 to over 1,400 pounds.
Here's how it's calculated: 0.5 kilowatt-hours of electricity per cubic meter of water and 177 grams of CO₂ per kilowatt-hour. The first value is a general guideline; there is no published average from British utilities. Enter your utility's value above. The second value represents the UK electricity mix for 2025, based on the UK government's conversion factors.
Why there is no monetary amount listed here. The cost of this electricity is already included in the rate per unit listed above. If we were to list it here as well, the amount would be counted twice. That is why only quantities are listed here.
What Early Detection Can Save
A leak loses the same amount of water every day. Therefore, the total amount of water lost depends primarily on how long it goes unnoticed.
Without continuous monitoring
- Time to Repair
- 193 DayDays until detection: 191 dayDays On average, half an inspection interval (183 days) plus on-site search (8 days) Without inspection, the leak continues; here, calculated as one year until the water reaches the surface and is reported until the repair team arrives on site: 2 days
- Loss during this period
- 256 m³kgal
- The Value of Water
- 1.341 €
With SmartEAR®
- Time to Repair
- 3 DayDays until location: 1 dayDays until the loggers report and the team locates the site until the repair team arrives on site: 2 days
- Loss during this period
- 4 m³kgal
- The Value of Water
- 21 €
- Loss Avoided Per Leak : Difference Between the Two Losses Until Repair, One-Time Payment Per Leak Incident
- 252 m³kgal1,320 €
Projected for your network, per year
- Leak size
- 1 mm
- 5 barpsi
- Type of leak
- Creeping through sand or gravel
- Control
- every 12 months
- On-site repair team
- 1 to 2 business days
- Duration per leak
- 193 days without, 3 days under supervision
- Total electricity cost
- 5.23 €/m³/kgal Drinking water only, excluding wastewater Drinking water 1.78 € + wastewater 3.45 €
per year
Both bars are on the same scale. Each segment represents one leak; when there are more than 20 leaks, the scale intervals are grouped together.
It is assumed that each year, the same number of new leaks occur, all of which are of the size specified above, are located in the same soil, and last for the same amount of time. In practice, they differ. The projection shows the order of magnitude.
When Your Investment Will Pay Off
The budget is spent at the beginning, leaving a negative balance. Each year, the avoided loss is added, and operating costs are deducted. When the balance reaches zero, the investment has been recouped.
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Red: The investment has not yet been recouped. Blue-green: It has been recouped; the amount above that is profit. Hover over a year with the mouse or use the keyboard to view the details.
Enter your budget, and the calculator will show you how long it will take and how many leaks it will take to recoup your investment.
Enter a unit price in the field above to calculate the payback period.
Here's how it's calculated: Balance after n years = n × (annual loss avoided − annual operating costs) − budget. The investment is recouped as soon as the balance reaches zero. Interest and price increases are not taken into account.
Why half an inspection interval? The inspection interval is not the duration of the leak. A leak can occur at any time between two inspections. If it occurs shortly before the next inspection, it will be detected after a few days. If it occurs shortly after an inspection, it will continue for almost the entire interval. When averaged over many leaks, a leak therefore remains undetected for half an interval—which, with annual inspections, amounts to about half a year. The entire interval would represent the worst-case scenario and would, on average, double the savings.
Here’s how it works: In permeable soil such as sand or gravel, water seeps away directly, leaving no visible signs on the surface. A leak like this isn’t detected until the next systematic inspection—on average, half an inspection interval later. Without regular inspections, it often goes undetected for years and shows up only as a loss in the annual balance sheet. On top of that, there’s the on-site search until the exact location is pinpointed. With continuous monitoring, the loggers report anomalies on their own, and the search team is guided directly to the affected location. The time it takes for the repair team to arrive on site is the same in both cases and is factored in; the repair itself is not.
Here’s how it works: Loam and clay trap the water. After weeks or even months, the water pushes its way to the surface—perhaps as a persistently wet spot in the asphalt or a conspicuously green patch of grass—and is reported by residents or the public works department. If the next inspection detects the leak sooner, that’s the one that counts. With continuous monitoring, the loggers detect the leak long before water begins to seep out. The time it takes for the repair team to arrive on site is the same in both cases and is factored in; the repair itself is not.
Even without technology, a pipe burst is usually detected within minutes to hours: Water visibly leaks out, water pressure drops in nearby homes, and residents report the problem. Faster detection offers little benefit in this case. The real value of continuous monitoring lies in detecting slow, creeping leaks that no one sees.
Real-world example: At Stadtwerke Witten, locating a leak without a logger took 6 to 7 days. (opens in a new window) Learn more about SmartEAR® (opens in a new window)
A separate calculation, independent of the comparison above: It considers a single leak of the size selected above that continues to leak without being detected, and compares the value of the lost water to the one-time cost of leak detection.
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$
£
- Value of the water lost up to that point
- One-time costs for leak detection
The location is recovered in less than a day.
After days, the water saved paid for the detection system.
After months, the water saved paid for the tracking system.
With this leak, it takes about years to recoup the cost of locating it. A larger leak or multiple leaks pay for themselves much more quickly.
Enter a unit price above to calculate the value of the lost water.
Enter the cost of leak detection, and the graph will show when it starts to pay for itself.
Assuming the leak detection system finds this leak and it is then repaired.
Find Leaks Before They Cost You Money
Let us provide you with a quote now to help you find leaks in your network and save money. The request is non-binding, and we usually get back to you within one business day.
The value of the water that would be lost until repairs are made without continuous monitoring averages 193 days per leak, compared to 3 days with SmartEAR®. This is a one-time cost per leak, calculated annually based on the reported number of new leaks.
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All hole sizes for reference
This overview is displayed regardless of your selection above and lists all sizes side by side. The selected size is highlighted. Calculated based on a line pressure of 5 bar and a flow rate of 0.62.
- 1 mm486 m³
- 2 mm1,944 m³
- 3 mm4,375 m³
- 4 mm7,778 m³
- 5 mm12,152 m³
- 7.5 mm27,343 m³
- 10 mm48,610 m³
- 25 mm303,811 m³
- 50 mm1,215,242 m³
- 100 mm4,860,970 m³
The amount of loss increases with the square of the diameter: a hole twice as large loses four times as much.
| Leak | Day (liters) | Week (liters) | Month (m³) | Year (m³) | Additional Costs per Year |
|---|---|---|---|---|---|
| 1 mm | 1.332 | 9.322 | 40,5 | 486,1 | 2.542 € |
| 2 mm | 5.327 | 37.290 | 162,0 | 1.944,4 | 10.169 € |
| 3 mm | 11.986 | 83.902 | 364,6 | 4.374,9 | 22.881 € |
| 4 mm | 21.308 | 149.159 | 648,1 | 7.777,6 | 40.677 € |
| 5 mm | 33.294 | 233.060 | 1.012,7 | 12.152,4 | 63.557 € |
| 7.5 mm | 74.912 | 524.385 | 2.278,6 | 27.343,0 | 143.004 € |
| 10 mm | 133.177 | 932.241 | 4.050,8 | 48.609,7 | 254.229 € |
| 25 mm | 832.358 | 5.826.505 | 25.317,6 | 303.810,6 | 1.588.929 € |
| 50 mm | 3.329.431 | 23.306.019 | 101.270,2 | 1.215.242,4 | 6.355.718 € |
| 100 mm | 13.317.725 | 93.224.075 | 405.080,8 | 4.860.969,6 | 25.422.871 € |
This overview is displayed regardless of your selection above and lists all sizes side by side. The selected size is highlighted. Calculated based on a line pressure of 60 psi and a flow rate of 0.62.
- 1/16″294 kgal
- 1/8″1,177 kgal
- 3/16″2,649 kgal
- 1/4″4,710 kgal
- 5/16″7,359 kgal
- 3/8″10,597 kgal
- 1/2″18,839 kgal
- 3/4″42,389 kgal
- 1″75,358 kgal
- 2″301,431 kgal
- 3″678,219 kgal
The amount of loss increases with the square of the diameter: a hole twice as large loses four times as much.
| Leak | Day (gallons) | Week (gallons) | Month (kgal) | Year (kg-al) | Additional Costs per Year |
|---|---|---|---|---|---|
| 1/16″ | 806 | 5.645 | 24,5 | 294,4 | 0 $ |
| 1/8″ | 3.226 | 22.581 | 98,1 | 1.177,5 | 0 $ |
| 3/16″ | 7.258 | 50.808 | 220,8 | 2.649,3 | 0 $ |
| 1/4″ | 12.904 | 90.326 | 392,5 | 4.709,9 | 0 $ |
| 5/16″ | 20.162 | 141.134 | 613,3 | 7.359,1 | 0 $ |
| 3/8″ | 29.033 | 203.233 | 883,1 | 10.597,2 | 0 $ |
| 1/2″ | 51.615 | 361.304 | 1.570,0 | 18.839,4 | 0 $ |
| 3/4″ | 116.133 | 812.934 | 3.532,4 | 42.388,7 | 0 $ |
| 1″ | 206.459 | 1.445.215 | 6.279,8 | 75.357,6 | 0 $ |
| 2″ | 825.837 | 5.780.861 | 25.119,2 | 301.430,6 | 0 $ |
| 3″ | 1.858.134 | 13.006.936 | 56.518,2 | 678.218,8 | 0 $ |
Calculated using the flow formula Q = Cd · A · √(2·Δp/ρ) for continuous flow. Actual losses depend on the shape of the hole, pipe friction, pressure fluctuations, and back pressure in the soil, and are usually lower than these values. These values do not replace leak detection or a water balance analysis in accordance with DVGW W 392.
Calculated using the flow formula Q = Cd · A · √(2·Δp/ρ) for continuous flow. Actual losses depend on the shape of the hole, pipe friction, pressure fluctuations, and back pressure in the soil, and are usually lower than these values. These values are not a substitute for leak detection or a water balance analysis according to AWWA M36.
Calculated using the flow formula Q = Cd · A · √(2·Δp/ρ) for continuous flow. Actual losses depend on the shape of the hole, pipe friction, pressure fluctuations, and back pressure in the soil, and are usually lower than these values. These values are not a substitute for leak detection or the leakage assessment required by Ofwat.
What is the outflow figure, and why is it 0.62?
The discharge coefficient, also known as the discharge factor, is a correction factor. It indicates what proportion of the theoretically possible discharge actually occurs. The reason for this is geometric: Water flows toward the hole from all sides and cannot change direction abruptly at the edge of the hole. It overflows, and the jet constricts behind the hole.
- Pressurized water
- Hole with area A
- Narrowest cross-section: width approximately 0.79 times the hole diameter, area approximately 0.62 times the hole area
The narrowest point is called the vena contracta, or constricted vein. It is there that the jet reaches its full velocity, and it is there that the jet is narrower than the orifice itself. The discharge rate is determined by two factors.
Contraction ratio: The ratio of the cross-sectional area of the vena contracta to the cross-sectional area of the hole. For a sharp-edged hole in a thin wall, the classical potential theory according to Kirchhoff yields the value π/(π+2) = 0.611. Measurements of round holes yield values ranging from 0.61 to 0.64.
Velocity coefficient: Friction loss. The water does not quite reach the theoretical velocity predicted by Torricelli. Measurements range from 0.97 to 0.99.
The product of these two factors yields the discharge coefficient: 0.63 × 0.98 ≈ 0.62. This value is therefore not derived but measured; it has been systematically measured since the 19th century by researchers including Weisbach and Hagen. In standard German literature, such as Bollrich’s *Technische Hydromechanik*, the value for sharp-edged boreholes is listed as 0.60 to 0.62.
| Shape of the opening | Flow rate | Liters per hourgallons per hour |
|---|---|---|
| Rough corrosion pit, crack | 0,55 | 49 |
| Sharp-edged bore | 0,62 | 55 |
| Short cylindrical tube section | 0,82 | 73 |
| Rounded Nozzle | 0,97 | 87 |
| Calculated without the discharge rate | 1,00 | 90 |
Why Some Tables List Higher Values If calculations are performed without a discharge coefficient—that is, using Torricelli’s ideal discharge—a 1-mm hole yields 89 liters per hour at 5 bar and 98 liters per hour at 6 bar. Such values are often cited, but they represent an upper limit that no one actually achieves in practice. The flow rate cannot exceed the area of the hole; therefore, a discharge number greater than 1 is physically impossible.
Why Some Tables List Higher Values If calculations are made without a discharge coefficient—that is, using Torricelli’s ideal flow—a 1/32-inch hole yields 13.5 gallons per hour at 60 psi and 14.6 at 70 psi. Such values are often cited, but they represent an upper limit that no one actually achieves in practice. The flow rate cannot exceed the orifice area; therefore, a discharge ratio greater than 1 is physically impossible.
Limitations of the Method: In the case of actual leaks in water distribution systems, the root relationship to pressure does not always hold exactly. In plastic pipes, a crack widens under pressure, and the cross-sectional area of the opening is itself pressure-dependent. In technical circles, this is known as the FAVAD concept, which uses a leakage exponent that can rise from 0.5 to as high as 1.5. For round holes in metal pipes, as assumed by this calculator, 0.5 remains the correct value.
Version History – Current Version 1.36.0
What has been added since the computer was turned on, with the latest version listed first.
Version 1.34
- The comparison with villages and cities names actual places, from Arnis to Tokyo.
Version 1.33
- New: A chart with one icon per person and a comparison with households; for large numbers, the comparison is with villages and cities.
Version 1.31
- New: Save or print the calculation as a PDF, clearly marked as a non-binding sample calculation.
Version 1.30
- Amortization shows the status of the investment year by year: The budget is spent at the beginning, and then the avoided loss is recouped.
- New: Annual recurring costs, such as for cell service, cloud services, and maintenance.
Version 1.29
- New: Payback Calculation Using Your Own Budget: How long it takes and how many leaks it takes for continuous monitoring to pay for itself.
- The number of leaks can be entered freely and applies on an annual basis.
Version 1.28
- New: A note before use stating that all figures are examples.
Version 1.27
- The payback chart is shown in a separate box, with the field for leak detection costs right next to it.
Version 1.26
- New: You can request a no-obligation quote right below the results.
- The avoidable amount specifies the time period to which it refers.
Version 1.25
- New: this version history.
- The reference to the success story of Stadtwerke Witten is clearly identifiable as a link.
Version 1.24
- The network projection is based on the following factors: leak size, pressure, type of leak, inspection, repair time, duration, and electricity rate.
- New chart: Losses from all suspected leaks with and without continuous monitoring, with each leak represented as a separate segment.
- Text and tables span the full width, making the calculator more compact.
Version 1.23
- New: Projection onto your own network with 1 to 10 presumed leaks of the same type.
Version 1.22
- New: Choose how quickly the excavation and repair team will arrive on site, ranging from 1 to 2 business days up to 2 months.
- The time to detection is broken down and explains why, on average, a leak remains undetected for half an inspection interval.
Version 1.21
- New: Leak type selection. Creeping leaks in sand or gravel, in loam or clay, and pipe breaks are detected after varying amounts of time.
- New level: “No regular monitoring.”
- A clearer presentation of the comparison than just two maps.
Version 1.20
- New: Compare how much water a leak loses before it is detected, with and without continuous monitoring.
Version 1.19
- New: Version for the United Kingdom with prices in pounds and British benchmarks.
Version 1.18
- New: Version for the U.S. with measurements in inches, psi, and gallons, and prices in dollars.
- Switch between unit systems. Each system retains its own prices.
Version 1.17
- The base price and tracking fees include the thousand-point mark; 1,200 is read correctly.
- Reading Guide for the Payoff Chart: Shows the accumulated value at any given point in time.
Version 1.15 – 1.16
- A clearer payback chart with a legend and a labeled intersection point.
- Consistent display in translated versions of the page.
Version 1.14
- New: Payback chart. It shows when leak detection becomes cost-effective.
- New: Information on how much water is saved for every bar of pressure reduction.
Version 1.13
- New: Electricity and CO₂ emissions caused by the lost water are counted as savings once the leak is repaired.
Version 1.12
- Choose between a light or dark color scheme.
Version 1.11
- The texts are intended for water utilities. Volumes are categorized as daily per capita consumption.
Version 1.8 – 1.10
- New: Share a calculation as a link without saving anything.
- New: QR code to view the calculation on your cell phone.
Version 1.7
- Fully translatable; numbers appear in the format of the respective language.
Version 1.6
- New: Fold-out explanation of the discharge figure, including a cross-sectional diagram and a table of values.
Version 1.5
- New: Optionally account for water temperature.
Version 1.4
- New: Bar chart comparing all hole sizes.
Version 1.2 – 1.3
- The selected hole size is displayed to scale.
- More compact interface; adjusts to the width of the page.
Version 1.1
- New: Costs based on the variable rate for drinking water and wastewater, plus a base rate.
- The summary table highlights the selected hole size.
Version 1.0
- Initial publication: Water loss from a leak per day, week, month, and year.