Every morning, you turn on your shower faucet, imagining washing away the impurities from the day before. However, even before the steam invades the bathroom, an invisible cloud of bacteria escapes from the shower head to tickle your face. Hot water running over your skin carries more than just soap, but should that be alarmed? Answer.
In the last meter of your pipes hides an entire tiny ecosystem. At night, while you sleep, microbial colonies organize inside the hose and shower head, taking advantage of a humid, warm and quiet environment. When you wake up, the first jet of water partially disintegrates them, projecting fragments of biofilm into the air – these viscous layers where bacteria live in communities, similar to microscopic cities.
The measurements taken in homes and laboratories are impressive, indicates a BBC article: hundreds of millions of bacterial cells can be found per square centimeter of pipe. Most are harmless, but some belong to less friendly genera, such as mycobacteria – distant cousins of those responsible for tuberculosis – or even fungi such as Exophiala or Fusarium, sometimes capable of causing infections.
These communities evolve: they grow, weaken, then start again depending on the use of the shower. After four weeks of regular operation, Chinese researchers observed a peak in proliferation before a decline, followed by a rebound after several months. They also detected the famous Legionella pneumophila, responsible for Legionnaires’ disease, particularly after periods of prolonged stagnation.
Rest assured, the risk for most of us remains low. According to Frederik Hammes, microbiologist at the Swiss Federal Institute of Aquatic Science and Technology, only showers contaminated with specific pathogens represent a danger, especially for fragile people. This is also the reason why hospitals regularly renew their shower heads and rigorously maintain their water networks.
Simple actions to adopt
But not all hoses are created equal. One study showed that flexible PVC pipe harbors up to a hundred times more bacteria than cross-linked polyethylene (PE-X) pipe. The first releases more carbon, a real feast for microbes. Opting for more neutral materials such as stainless steel or chrome-plated brass would therefore limit their installation. Conversely, rain showers or “low consumption” showers – as virtuous as they are – increase the formation of fine aerosols capable of carrying bacteria into the air.
The “antibacterial” gadgets touted by certain brands do not keep their promises. Built-in filters or silver ions have little real effect on microbial load. “Studies show that they modify the composition of colonies more than they reduce them”explains Sarah-Jane Haig, professor at the University of Pittsburgh.
Fortunately, a few simple actions are enough to limit exposure. Start by not standing in the shower for the first few seconds. Let the water run for a minute or two, time to flush out the accumulated micro-organisms – after a prolonged absence, this is all the more essential. Maintaining the water in the water heater at 60°C also helps deter Legionella, while regulating the outlet temperature with a thermostatic mixer to avoid scalding.
Ventilating your bathroom just after showering also reduces the concentration of suspended particles and an effective air extractor can significantly reduce the number of contaminated micro-droplets. As for the pommel, a regular passage with very hot water or a bath in lemon vinegar will be enough to disrupt the biofilms. Vulnerable people can also consider changing their hose and shower head every year.
Ultimately, your shower isn’t as “dirty” as it looks, it’s simply alive, brought to life by a complex microcosm. You can never chase it away for good, so you might as well figure out how to live peacefully with it.
