Drinking Water Quality
The quality of drinking water on board of airplanes is the subject of many discussions.
People seem to worrie mostly about the presence of bacteria (e.g. E-coli), besides the growth of fungi and algae
in the storage tanks and pipes on board.
Airlines will invariably reassure you that the drinking water on board is perfectly safe, and subject to numerous quality checks.
But they are less keen to provide information about the time intervals between thorough cleanings of the tanks and pipes. At the same time, several chemicals, a.o. Chlorine compounds, are added to the water to kill any fungi and bacteria. So it’s not so surprising that in particular tea served on board often has a strong “extra” taste. The same goes for coffee, albeit to a lesser degree, as coffee has a more predominant taste of its own. It is therefore with good reason that many cabin attendants will use only bottled water when making themselves a tea…
A few quotes from the internet:
- “From American research in 2009, the drinking water in one out of seven airplanes appeared to be contaminated with E-coli. This bacteria is a major cause of food poisoning. So the advise to be cautious in drinking water on board is certainly not unfounded.” (Source: de Telegraaf, 2014)
- “Multiple studies showed drinking water in airplanes to be full of bacteria. This was even confirmed by EPA and the Wall Street Journal. And when the water isn’t clean, neither is the coffee. You’d better order a bottle or a tin of Coke, so the bacteria will not bother you.” (Source: Amayzine)
Another (maybe less known) reason why using drinking water on board is not advisable, is the fact that the water storage tank is located in the cargo area, below the passenger compartment. To transport the water to the taps in the cabin however, no electric pump is used as one might expect. Instead, the system is pressurised by… Bleed Air! This is a cheap and effective way of transportation, but with one BIG objection: this air, just like the air for pressurisation and air conditioning, comes directly and unfiltered from the engines (except for B787). Consequently, it is by definition contaminated by oil fumes. The water on board is normally not drained completely, but refilled during ground stops. As a result, it will on average be in the storage tanks for considerable time, constantly in direct contact with this contaminated air.