Water Loss Due to a Leak
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.
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.
- per day
- 1,332 litersgallons 1.33 m³kgal 5.99 €
- per week
- 9,322 litersgallons 9.32 m³kgal 41.95 €
- per month
- 40,508 litersgallons 40.51 m³kgal 182.29 €
- per year
- 486,097 litersgallons 486.10 m³kgal 2,187.44 €
Annual Cost
- Drinking Water Award
- 729,15 €
- Working Price for Wastewater
- 1.458,29 €
- Additional costs due to the leak
- 2.187,44 €
- Base price remains unchanged
- 0,00 €
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.
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.
- 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 will take more than two years to catch up on the detection work.
Enter a unit price above to calculate the value of the lost water.
Enter the cost of leak detection in the field above, and the graph will show you when it pays for itself.
Assuming the leak detection system locates this leak and it is then sealed.
The link contains your entries. Nothing is stored on the server.
Link copied.
Please select the link manually and copy it.
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
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 | 2.187 € |
| 2 mm | 5.327 | 37.290 | 162,0 | 1.944,4 | 8.750 € |
| 3 mm | 11.986 | 83.902 | 364,6 | 4.374,9 | 19.687 € |
| 4 mm | 21.308 | 149.159 | 648,1 | 7.777,6 | 34.999 € |
| 5 mm | 33.294 | 233.060 | 1.012,7 | 12.152,4 | 54.686 € |
| 7.5 mm | 74.912 | 524.385 | 2.278,6 | 27.343,0 | 123.043 € |
| 10 mm | 133.177 | 932.241 | 4.050,8 | 48.609,7 | 218.744 € |
| 25 mm | 832.358 | 5.826.505 | 25.317,6 | 303.810,6 | 1.367.148 € |
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.
- 1/32″74 kgal
- 1/16″294 kgal
- 1/8″1,177 kgal
- 3/16″2,649 kgal
- 1/4″4,710 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 |
|---|---|---|---|---|---|
| 1/32″ | 202 | 1.411 | 6,1 | 73,6 | 0 $ |
| 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 $ |
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.
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.