Measuring flow velocity in (swimming) pools

Measuring efficiency and safety of counter current systems and filter pumps

Process data

Measuring task:
Flow velocity measurement in pools

Measuring point:
Under water with a certain distance to the counter current system’s nozzles or close to the water suction etc.

Measuring range:
Up to 2 m/s

Process pressure:

Process environment:
From 20 – 35 °C

Recommended products

Vane wheel anemometer ZS25

ProductProduct data Sheet

Handheld unit flowtherm NT.2

Productproduct data Sheet


There are different reasons for measring flow velocity in pools. Such as safety aspects, the goal to have a defined flow velocity in counter current systems or massage nozzles etc. Other possible applications are thermal baths and pools with flow channels. Even in very special applications for flow velocity measurement in pools Höntzsch offers  suitable measuring instruments.

Your advantage

By measuring flow velocity the resistance level on the swimmers can be precicesly adjusted.

Flow measurement at the water suction ensures safety of the pool visitors.

The probe can measure flow at any spot in the pool. Measuring results can be saved in the handheld unit and later evaluated.

Tried and tested
For decades Höntzsch vane wheel sensors have been used to measure flow in open waters (for example in fish farming/fish breeding). Users are communes, universities, research facilities and engineering firms.

Flow measurement in hotel and public pools

Höntzsch flow measuring sensors are used to ensure swimmers’ safety through water flows or adjust velocity of a counter current system. Höntzsch vane wheel sensors can also measure in white water in water parks. They also aid in the optimal adjustment of water flows towards the filter system.

Detailed examples of flow velocity measurement in pools:

1. Pool safety

There’s a whole range of national and international accident safety rules for swimming pools for example EU standards DIN EN 13451, DIN EN 15288 as well as standards DIN 19643 which in Germany is the athoritative set of rules for the preparation of swimming pool water, as well as leaflet DGfdB – R 65.07 and operating rules for pools BGR/GUV-R 108.

The variety of rules and regulations makes it clear that any measurement regarding hotel pools or public pools and training pools it’s all about safety. The suction parts of a pool can be especially dangerous for children if the suction is too strong so it needs to be avoided at all costs. The maximum permissible suction power is defined in DIN EN 13451-1 and -3, in policy R 60.03 of the German society for bathing. It’s a maximum of 0.5 m/s at the opening areas of the outlet grilles. With the help of our vane wheel anemometer and the matching handheld unit, suction in a pool can be precisely measured. The values are saved in the handheld unit and can later be transferred to a central computer for archiving.


2. Why do travel agencies check pool safety in hotels?

The operator is liable for any accident in the pool that traces back to technical defects in the system. Travel agencies want to minimise any possible risks worldwide to avoid damages of image and potential fincancial compensation for damage. That’s why they hire for example TÜV-organisations for these flow measurements.


3. Competitive swimmers want to know it exactly

Competitive swimmers use counter current systems to train in small spaces in one spot. That way the coach can easily give commands to improve their swimming style for example. Video recordings are easily possible and allow the swimmer to analyse themselves. But how fast does the athlete swim? To determine exact flow velocity a measurement instrument has to be used. This happens at a certain distance from the outlet nozzle and in different water depths. That way the athlete knows how they perform in which setting of the system.

Click here for the report about flow velocity measurement in the training pool of a competitive athlete.


4. How can characteristics of flow nozzles be optimised?

Another flow measuring task is checking and optimising characetristics of flow nozzles for pools and water parks. Design and flow mechanics is a science in itself. Nozzle manufacturers use flow measurement to study the concept of their flowed through components. Only the for the task optimally designed nozzle ensures long-term market success.


5. How can flow measurement in pools prevent sunburn?

There‘s a special application of this measuring task in dermatological research and development, where water resistance of sun screen is being testet. Defined flow conditions in a pool show the abrasion of sunscreen and therefore the effects it has on the sun protection factor. The goal here is to adhere to applicable standards.