Water Hygiene in Motorhomes

6 answers to some of the most frequently asked questions about “Water Hygiene in Motorhomes”.

1. Why does the quality of the fresh water in the motorhome play an important role – even if I don’t drink the water?

I keep coming across this question. Basically one must know that in drinking water, even in Germany according to current German drinking water regulations and high quality standards, 100 CFU (nucleating units: bacteria, fungi, yeasts etc.) are allowed per 1ml of water with drinking water, as well as the fact that microorganisms also multiply faster with rising temperature. Beginning at approx. 10°C, bacteria multiply, which for example equals triple the growth rate at 25°C. Boilers in recreational vehicles are generally operated at temperatures between 40°C and 60°C. This makes sense from an energy point of view, but is disadvantageous from a hygienic point of view. According to a recent study by the Helmholtz Centre for Infection Research (HZI) in Braunschweig, legionella, for example, multiply even at temperatures between 50°C and 60°C. If you have an intact immune system and you drink water contaminated with Legionella, the risk of illness is very low. But when taking a shower, for example, it’s a different matter. Legionella aerosols can be inhaled via the fine water mist generated during showering. These cause long-term damage and can cause serious infections such as legionellosis (pneumonia). Even if you use the water exclusively for washing dishes, I think a certain basic level of water hygiene should be guaranteed.

Question and Answer session with Michael Würtemberger, Dipl.- Ing. in Supply and Environmental Technology (FH) and Managing Director of WM aquatec GmbH & Co.KG

“Even if you use the water exclusively for washing dishes, I think a certain basic level of water hygiene should be guaranteed”

2. How should the risk of Legionella in freshwater systems be assessed?

The health consequences of Legionella in one’s freshwater system can be drastic and should not be underestimated. In Germany, around 3,000 people die every year from the results of legionellosis. By comparison: in 2017 there were around 3,200 road deaths in Germany.

3. In light of these facts, what do you recommend for hygienic operation of a freshwater system?

The frequency of cleaning and disinfection of the freshwater system depends primarily on user behaviour. In principle, however, it makes sense to disinfect the system every 3-6 months if there is year-round use. The standard for rental vehicles according to DIN 2001-2 is 3 months. If you go on holiday only 1 or 2 times a year, I recommend cleaning and disinfection at least once before the season. In Central and Northern Europe, water conservation is also recommended. Disinfection of water is necessary if you are in Southern Europe or outside Europe and/or if you find an unknown or untrustworthy source of water.

“The frequency of cleaning and disinfection of the freshwater system depends primarily on user behaviour”

4. What is the fundamental difference between conservation and disinfection?

This is an important aspect that needs to be distinguished. Conservation is the prevention of the proliferation of microorganisms over a longer period, in this case in a fresh water tank, including the hoses, up to the fitting. However, this requires water of drinking water quality. Disinfection is based on the assumption of a high level of germs or bacteria in the water, which is reduced by the addition of disinfectants in order to make the water potable.

“Conservation is the prevention of the proliferation of microorganisms over a longer period”

5. Which active substances are useful for conservation?

Silver-based products have been used since the time of Charlemagne to keep drinking water fresh. At that time it was still in the form of silver vessels in which the drinking water was stored, as nothing was known about the specific mode of action of silver. Today it is known that the positively charged silver ions dock with the microorganisms (e.g., pathogens such as Legionella, E. Coli etc.) and disrupt the bacteria metabolism or lead to cell death in over 30 different mechanisms of action. The microbial silver ions have a unique long-term effect like no other active ingredient on the market. Products based on chlorine or hydrogen peroxide cannot be “bound” in water; they evaporate and are therefore not suitable for conservation.

6. Disinfection products containing chlorine often have the same smell/taste – are there alternatives?

Yes, there are. As an alternative active substance, there is in Germany — according to current drinking water regulations — for example, chlorine dioxide, which indicates chlorine in the name, but has no similarity with chorine. Chlorine dioxide is a very broadly-acting disinfectant and also has deodorant properties, i.e. odours and flavours in the water are converted or not produced at all. In contrast to chlorine, far fewer disinfection by-products such as chlorophenols or AOX compounds are formed in drinking water. While chlorine already loses 25% of its disinfection effect at a neutral pH value of 7 (and even over 65% at pH 7.8), this is not the case with chlorine dioxide. Products containing chlorine dioxide are therefore a real alternative to drinking water disinfection.

“Products containing chlorine dioxide are therefore a real alternative to drinking water disinfection”