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Recently, I've started drinking more and more tap water instead of buying bottles all the time (which is usually absolutely no issue in Germany).

I like to use a bottle for that not fill a glass all the time. At the moment, I'm using 1-l-bottles like this. They're meant to be reused, and the plastic is harder than for single-use bottles. I could not find the exact kind of plastic, though.

My question is be how often and how I have to clean that bottle. I'm drinking directly from it, but I'm not sharing it and using only tap water, nothing else. I'm refilling it around three times a day approximately.

Is rinsing the bottle opening with tap water once a day and using dish soap once a week reasonable, or more than necessary, or not enough?

6

If your water source is clean and assuming you are a relatively clean person in a fairly clean environment (not working in sanitation), You can probably get away with never cleaning it and not get sick. Tap water usually has some chlorine in it to keep basic bacteria and virus levels low. So refilling it with this water will keep the general levels low inside the bottle.

Contamination will primarily come from you -- your hands and mouth. Your body is constantly fighting off bacteria and viruses and the levels you transfer to the bottle will be quite low and easy for your body to kill. However if bacteria left unexposed to the cleansing tap water (like trapped under a piece of food or debris) they can multiply. In these cases the most common bacterias will alter the flavor of the water, however your body will easily fight them off.

Unless you are sick or very unclean (wiping the lip of the bottle with dirty hands), the amount of harmful animals transfered to the bottle will be very small.

Allowing the bottle surfaces to completely dry will kill a large range of bacteria, and rinsing/washing occasionally will also remove debris where they can breed.

An occasional rinse with vinegar will help destroy both viruses and bacteria on many of the hidden surfaces that the chlorinated tap water isn't strong enough to penetrate completely. Vinegar is also non-toxic to drink.

For example I live in the tropics where bacteria and viruses thrive in the heat and humidity. In our case the water is chlorinated, but the water is filtered through a charcoal filter before being placed into the bottle to reduce the chlorine levels (the bottle itself does not get the benefit of the chlorine to clean it). With daily use (and drying, but not washing) it can take several months before a water bottle starts to taste off and a vinegar rinse removes it. We also store water in water bottles that we do not put in our mouths, but pour directly from them. In this case, they are on their second year of never being washed and are fine.

7

Given that your water is clean I don't think cleaning the bottle is a major concern. Personally I would rinse a water bottle out with tap water before filling (or maybe once a day if using it lots) and only bother with soap if visibly dirty.

Therefore I would say your suggestion is more than necessary but not excessive.

For reference I fill my water bottle for cycling to work most days and clean it less than I recommended (I don't clean it at all if filling from the office water cooler) and I haven't had any ill effects yet.

One case where I would recommend you clean your bottle well is if you leave it filled for a long time (say over a week), particularly if it is left in direct sunlight. In this case bacteria/mold can grow in the water which you probably don't want to be drinking.

From a hiking perspective, providing that the water is drinkable, I would apply pretty much the same principles. Although I would be even less keen drink water then has been standing a long time.

  • 1
    Thansk for your answer, sounds reasonable. Though concerning leaving it in the sun, I'd say that depends on whether the UV light hits it directly or if things such as window glass filter out a lot of it. If there's no filter and it's the right kind of bottle, Solar water disinfection might come into effect. – helm Oct 7 '14 at 17:23
  • The WHO actually has a method for sanitizing water bottles by placing them in the sun (google SODIS). Here is an interesting table of comparisons. who.int/water_sanitation_health/dwq/0207tab20/en – user6972 Oct 8 '14 at 21:49
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As long as the water you are filling it with is clean, it won't be the problem. What may cause an issue is your mouth. Human mouths are not especially clean, and while microorganisms are kept at bay in the mouth, they can start to multiply rapidly in water.

I always recommend washing bottles once a day. As a simple, convenient and quick hygiene step it removes one worry from your list of health checks.

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    To avoid contamination from your mouth, don't drink from the bottle (or if you do, learn the technique of pouring from the bottle into your open mouth rather than putting your lips to it). – nekomatic Oct 9 '14 at 12:03
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More important than the cleaning is, in my opinion the choice of the bootle. I switched to a bottle explicitly designed for a use like yours, in my case a Nalgene drinking bottle. My reasons for doing so:

  • Health concerns:
    While I think there are regulations about what materials are allowed in drinking bottles, they have shown to be insufficient in many other areas. Soft plastics often contain softeners which have hormonal or cancer-inducing effects. The nalgene (and others designed for this purpose) bottle is BPA-free.

  • Hygienic reasons:
    The wide-mouth bottles are super easy to clean. You can easily clean the inside as well.

  • Practical reasons:
    The lower building form allows for easy refills, even under lower taps. If you have problems drinking from the wide-mouth models (which is not as easy as it looks!), you can buy an adapter or one with a smaller opening. These bottles are also very useful for outdoor use (for example because of the scale on their side) and can therefore be found in nearly any outdoor store.

  • Environmental concerns:
    Because they are easier to clean and more durable, it is the better choice to buy a good bottle once and use it for months or even years.

About your original question, how (often) to clean it:
I clean my bottle every couple of days to prevent them from smelling. I wash them by hand with normal dishwashing-soap, but you could also put them in the dishwasher, if you have one. If you really want to desinfect them thoroughly (which seems like a little bit of overkill for me, since I never had any problems), don´t use boiling water, since this could destroy the coating of the bottle and make bad substances solve in your water (this is true for any plastic bottle!). I would use vinegar for desinfecting.

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Cleaning once a week may be slightly more than enough, but it is reasonable. Depending on your environment, there may be factors that cause the bottle to smell bad.

Something I have learned from biking is to store the empty bottle in the freezer at night, or when not in use. Freezing kills a lot of things and prevents growth of mold/mildew. It has the added benefit of slightly cooling your water when filled in the morning.

My recommendation would be:

  1. Rinse it out when filling
  2. Freeze it while empty at night when possible
  3. Wash with soap when you feel it needs it.

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