Water temperature

Open water swimming competitions and triathlons are becoming increasingly popular. Good water quality is obviously vitally important in these situations to prevent health problems. For the ITU World Triathlon Grand Final in Rotterdam we are proud to announce the partnership with Eijkelkamp Soil & Water so that participants will always have access to the latest information.


In order to detect poor water quality on time, it is important that this quality is monitored. Using the mobile water quality instrument from Eijkelkamp Soil & Water, organisations are given continuous insight into the quality of the swimming water and can be promptly warned of abnormal values so that action can be taken. You can also check the real time water temperature of the Rijnhaven here.


The mobile water quality instrument will stay in the Rijnhaven until September 18, 2017.


Click on the image or here to check the temperature.

Eijkelkamp Soil & Water’s mobile water quality instrument measures the following parameters:


This parameter indicates the quantity of free oxygen molecules in the water. The oxygen concentration is an important indicator of the health of the water system, because oxygen is essential to life. Very low oxygen concentrations will nearly always lead to the death of organisms which results in the presence of the wrong kind of bacteria in the water. Ultimately this can lead to botulism. Botulism starts off with nausea, vomiting, fatigue, dizziness, general weakness, a dry mouth and stomach complaints. Botulism can eventually be fatal. Cold water can hold more oxygen than warm water, so the chances of pollution in low temperatures are smaller. Good oxygen concentration levels are above 4 mg/L.



Temperature affects the level of acid in water. Each organism has a specific temperature at which it is happiest. When the temperature deviates too much, the ecosystem becomes unbalanced. A pleasant temperature for people is in the range 18 to 25 degrees. Bacteria also find this to be a pleasant temperature, which can cause problems. High temperatures over a long period of time can cause contamination with E-coli and streptococcus bacteria. These bacteria cause abdominal complaints, fever and a feeling of severe weakness. Natural causes of temperature fluctuations are rainfall, groundwater influx and cloudiness. Human causes are often the discharge of cooling water and dumping of waste water from a water purification plant. The location where the readings are taken can also produce large temperature differences. When the sun shines on an exposed pond, the water temperature can get much higher than when the water is in the shade.


Cloudy particles in water retain heat causing the temperature in the water to increase. Warm water holds less dissolved oxygen than cold water, so the oxygen levels in cloudy water will fall more quickly. In addition, Turbidity is restricted by cloudy particles in the water. This reduces the process of photosynthesis and in turn the production of dissolved oxygen. Sudden changes in cloudiness may point to contamination. With regard to swimmers it is also unwise to swim in cloudy water. If a swimmer becomes unwell during a competition, it may be hard to find them if visibility is very limited. Good turbidity has a value below 100 NTU.


Further information

If you organise swimming competitions or triathlons in open water and you would like insight into the water quality, call Leon van Hamersveld at Eijkelkamp Soil & Water on +31 313 880 200 or email him at sales@eijkelkamp.com.


Water temperature