Summer holidays – for our auditors from the Systems division this is a busy time of the year. Because then it’s time once again for so-called “Mystery Checks” at public swimming pools or hotels in popular holiday regions. Mystery Checks, as these undercover inspections are called in Germany, serve to check compliance with management system standards. One aspect assessed by the auditors is quality management. Hotel and swimming pool operators do not know when our inspectors will show up – sometimes they don’t even know that such a check will be performed. This was also the case with the undercover audits of public swimming pools in Cologne and the surrounding area, which we carried out in cooperation with the Kölner Stadt-Anzeiger newspaper.

Undercover public pool audit

The auditors do not appear in TÜV Rheinland clothing, but arrive at the outdoor pool as normal customers. They pay admission and lie down on the sunbathing lawn wearing trunks or bikinis to make some observations initially. This is because observation accounts for the bulk of the audit. The general impression is first documented by means of a checklist. How good is the signage at the swimming pool and are there enough parking spaces? Are the principles of data protection observed when entering the public pool grounds? What about fire protection and escape routes? These are important things that a normal guest usually doesn’t pay any attention to; but they are of enormous importance for our safety.

We continue with the assessment of the basin and the slide. Are they structurally sound? Is the bottom of the pool visible? Are there any loose screws, sharp edges or tripping hazards? But that’s not all: from the changing rooms to additional facilities such as playgrounds, everything is scrutinized and also recorded in a photo documentation. It is not that easy to photograph all the “pieces of evidence” as inconspicuous customers – from the abandoned French fries fork on the lawn to the high-voltage power cable of the sausage trolley.
Mystery Check

The Currywurst must be hot

Speaking of fries and sausage: of course, the catering services available at the pool are also checked. In order to be able to compare the various pools, auditor Alina Roeder, who I was allowed to accompany one day during the Mystery Check, ordered Germany’s favorite pork sausage –Currywurst – and fries at each pool. In addition to the taste, the hygienic specifications are also checked. The auditor uses a thermometer to measure whether the fries and sausage are hot enough – that is, whether they have been freshly prepared rather than having spent a couple of hours on the hot plate. Our expert also immediately reveals the trick of pouring warm sauce over old sausage. The thermometer doesn’t lie. According to the DIN 10508 standard, Table 4, French fries and pork sausage must have a serving temperature of more than 65 degrees Celsius . For comparison, here is the photo documentation from one of our inspections:


The temperature of 81.1°C of the fries is fine. Here the temperature of the sausage without sauce was measured. At 60.9°C, it is clearly below the required minimum temperature. The taste test also shows that this Currywurst tastes cold and stale. The operator of the snack stand tries to hide the fact that their sausage has been prepared quite some time ago by pouring hot sauce over it. The thermometer shows that this attempt also fails, as the sausage remains at a temperature slightly below the minimum requirements even with the hot sauce.

And what about the hotels in holiday locations?

Many holidaymakers are not only drawn to public swimming pools in summer, but further away to popular holiday regions such as Greece as well. Amidst all the anticipation of the booked trip, one question often is on people’s mind: Is the booked hotel really as beautiful as it looks in the photos? After all, you have saved the whole year for the family holiday. This is why undercover inspector Olaf Seiche also checks hotels in popular holiday regions. He books himself into the hotel like a normal guest and puts the entire facility through its paces. The bottom line is: no matter how expensive or affordable a hotel is, it must always be clean and hygienic. Of course, the safety of the guests also has top priority during these undercover checks.

Even though our system auditors not only carry out mystery checks, but also check “normal” quality standards such as ISO 9001, I am not only positively surprised after my internship day, but also very pleased with the work of my colleagues. They do everything for our safety.


Viktoria Kux

Viktoria Kux

Social Media Manager

Viktoria Kux is Social Media Manager in TÜV Rheinland’s newsroom and responsible for all German-language social media channels of the company. Whether it’s a new photo for Instagram or a video for YouTube that needs to be produced – her everyday work revolves around all social networks.

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