I read today that 99% of bacteria live in colonies and attach to surfaces as biofilms. If you carry a reusable water bottle you might open it and rub your finger along the inner surface. My bet is that you’ll feel a slick coating on the inside surface of the bottle. That is biofilm, a colony of bacteria.
80% of all infections in humans come from biofilms according to Veysel Berk at UC Berkeley in a study published in the July 2012 issue of Science. A single bacteria is able to attach to a surface, start reproducing, and launch a reproducing colony that becomes a biofilm.
Bacteria’s ability to reproduce is one reason I advise private well owners that treating their well using chlorine or even hydrogen peroxide is only a temporary solution. One must kill every individual bacteria, which is highly unlikely, or the colony will reestablish itself. A whole house UV light provides protection from bacteria entering the home. If you install the UV light at the same time you disinfect the well then you have provided a more long term solution to the problem of bacterial contamination of well water.
Most bacteria are harmless to humans. Still…that is not always the case. For instance there is the newly prominent brain eating bacteria that is the scourge of Neti Pot users (see article below). But most are harmless: your showerhead, your bathtub faucet, and even your kitchen faucet is home to colonies of bacteria which get flushed out each time you turn them on. That’s why it’s good to run a bit of water before filling a container or jumping in the shower. Faucets can be treated by dipping them in vinegar. This is accomplished by hanging a small bag containing vinegar on the faucet or showerhead.
Bacteria can also colonize your water filter. For this reason I employ KDF media in my kitchen water filters. KDF creates an anti-bacterial environment within the filter using a small electrical charge, or ionization. Some people use carbon impregnated with silver as a bacteriacide. I don’t like this approach because I suspect that drinking the silver can kill the beneficial bacteria in your body.
It is a good idea though to clean your filter housings with every filter change. I recommend filling each housing with hydrogen peroxide and then running water to the filter faucet and letting it sit. The hydrogen peroxide will oxidize, or consume, the bacteria or biofilm. This is another reason I don’t recommend using the same filter for multiple years even though it may have some contaminant removal capacity remaining. It’s a good idea to change filters and clean the housings annually because the inside most likely does contain a colony of bacteria.
If you’re using a water bottle repeatedly you might stop right now and soak it with a solution of half vinegar and half water to kill bacteria. Water bottles become contaminated from our hands and from our mouths. So you have to clean them often. After you do, stick your finger inside and see if the film is gone. Now that you’ve touched it, you’ll need to clean it again. Even though bacteria are everywhere and most are harmless to humans it’s a good idea to take small precautions such as these to keep them in check.