Retention Tank
The retention tank selection application was developed in cooperation with a leading company in the field of production of concrete retention tanks, Ecol – Unicon. This tool allows for quick selection of the appropriate tank from the Hydrozone series using the most reliable rainfall data from the Polish Atlas of Rain Intensity.
The application allows for better design and adjustment of the retention tank to specific needs in four simple steps. It also contains useful elements for construction planning, such as the functionality of using rainwater. After making the selection, the system generates a PDF file that contains information such as the size of the retention tank, the value of the outflow, the functional diagram of the tank with capacities and a description of the selected functionalities.
The application is available in Poland.
Calculating the capacity of a retention tank
Calculating the capacity of a retention tank
How to calculate the capacity of a retention tank using the application?
To perform the calculations, the following data are required:
- the probability of rain occurring expressed as a percentage,
- the frequency of calculated rain,
- the assumed flow time through the channel [5-30 min],
- the permissible discharge limit, i.e. the maximum acceptable discharge of rainwater specified by the Manager or Network Operator.
Then it is necessary to select from the list the so-called reduced areas and provide their area:
On this basis, the individual choked outflow will be calculated.
In the next stage, it is possible to select additional tank equipment and indicate additional water destination, e.g. for fire protection, irrigation or municipal purposes. The application will take this data into account when selecting the retention tank.
Retention tank selection results
Based on the information provided, the application calculates:
- minimum tank capacity based on the selected precipitation model,
- total inflow to the tank,
- total outflow from the tank,
- tank emptying time,
- internal height of the tank,
- usable height of the tank.

Calculation results
Once you have made the correct selection, you can download the results as a PDF file and place them in your project.
Additionally, at any time you can directly contact the manufacturer of the solution to ask about the details of the selection, the accuracy of the calculations or request a quote for the solution.