AS-TOMMYSHAFT overflow serves for current flowrate measurements at the discharge from premises, where water streams are collected in retention, soakaway, or similar structures. From these premises, water flows away in a controlled manner to sewers or receiving watercourses. After its calibration, the relevant equipment is used as a billing meter of actual flowrates. In this way, the developer enjoys savings because the bill is based on the water quantity actually drained away and not on a lump sum charge calculated based on drained areas. AS-TOMMYSHAFT is designed according to the requirements of the new TNV 259305 Standard “Measuring systems of water amount passing-through in profiles with free levels”.

This system of rainwater measurements is repeatedly designed as a measuring point situated beyond retention and soakaway structures, with flowrates in the range from 0.1 litres per second to 39 litres per second.


We are able to supply this measurement equipment on a turnkey basis, i.e. the measuring device (plastic shaft, stainless-steel overflow), ultrasound probe, including the evaluation unit, installation works (plus calibration), and official approval (as a billing meter).

AS-TOMMYSHAFT is offered in a double-jacket design:

  • Double-jacket polypropylene structure prepared for concreting of the space between the jackets.
  • Suitable for demanding foundation conditions, i.e. faulty foundation grounds, waterlogged soils with significant effects of underground water.

ASIO AS-TOMMYSHAFT měření průtoku dešťových vod

The height difference between the overflow edge and the discharge pipe from the premises is 600 mm. Therefore, it is necessary to respect this value and reflect it in the equipment design. This operating height cannot be reduced; it will be necessary to calculate with burying the discharge pipe to an adequate depth.