Soft drinks in my office’s community fridge keeps disappearing. How to deal with this?

What are other people bringing/doing?

Is there a norm where other people are bringing in 2 liter bottles or are you the only one? Is there an understanding amongst the team that individual servings like cans are personal while large bottles are for sharing? Do people label things in the fridge?

These types of questions are worth figuring out or asking to whomever you can trust to give you an insightful answer to how your office works. It may turn out there is someone who regularly brings in leftover 2 liter bottles from events, and so anytime there is a 2 liter bottle in the fridge it means someone wants it gone. Or every Monday the manager brings in some 2 liter bottles for the team to enjoy and your 2 liter bottle is getting mixed up with it. Or there is an understanding unless there is a name in big black sharpie marker it is fair game (my team is the reverse where if you want something fair game you have to label it FREE or something similar).

Observe

For now it may best to not bring in any sharable beverage you do not want others to consume until you have had a chance to observe how other people use the fridge, and understand what office understandings govern it. Also observe to see if anyone else is complaining about people raiding other people's beverages (or lunches for that matter), since that would indicate this is an active and known issue and so you can safely chime in that you too have been impacted.

Alternatives

When all else fails, the question becomes: Is there an alternative way for me to enjoy my soda? You have mentioned a few ideas that are viable, but have various drawbacks. You will have to weigh if the drawbacks are worth it. Though I do recommend the soda in an opaque plastic bag in the back of the fridge with your name on it. Someone would have to put in quite a bit of effort to get it, and should get the hint that it is not intended to be shared. This step also provides some good evidence if you do have to file a complaint that you did take steps to avoid any miscommunication and that someone was actively and aggressively taking stuff from the fridge that was not theirs.

In my experience, large bottles of soft drink in the work fridge are leftovers from catering, and are free game to consume and also dispose of.

I would try switching to single-use can/bottles of soft drink. Only leave one in the fridge at a time and consume it on the day that you put it in.

You're assuming that people are taking your bottle to drink from. However, you also say that the fridge is for people to leave their lunches, and typically people wouldn't be leaving their lunch in the fridge for more than a few hours at a time. As it stands, you haven't offered any proof or observations that support what you claim has been happening, so you shouldn't be jumping so quickly to assuming that everyone is stealing from you especially if it doesn't seem like anyone else is having this problem.

As such, might I suggest an alternative possibility: the fridge is getting regularly cleaned out because it was never intended for people to leave their items in it long-term. This is an entirely reasonable policy seeing as it would affect everyone if someone ended up forgetting their lunch and leaving it in there to rot for days or weeks. I suspect that whoever is cleaning out the fridge (every other night or whatever) isn't seeing someone's soda stash but rather a partially drunk and likely abandoned bottle of soda.

I also want to suggest that you consider your own conduct for a moment. You have been assuming that it is acceptable that you use this fridge as your own personal drink storage long term, and depending on the number of other people that use this fridge, I would hazard a guess that that is not a correct assumption. Even if you say that you don't mind if other people occasionally help themselves to a drink, your attitude suggests that you still expect people to respect that it belongs to you which goes back to your treating the community fridge like its your own personal storage space. The longer you do this, the more likely it will be that your behavior will end up rubbing people the wrong way, which is not something you want to be doing especially when you only just started working there.

You should talk to your manager or supervisor, but not with the goal of finding and punishing the presumed thieves but instead with an open discussion about the fridge policies in general. Ask if the fridge does indeed get cleaned out regularly, and if leaving your large bottle of soda in the fridge long term is even something you should even be doing. Maybe you can try to negotiate some kind of arrangement where you clearly label your bottle that not only is it yours but that it shouldn't get thrown away. Of course, whoever cleans the fridge might not be looking too closely at labels, so whether or not your arrangement gets honored might not be something you can reliably depend on.

And if you do find proof that a person or persons have been stealing swigs from your bottle, you can address that situation then.

Depending on what you most want to achieve, there are a few approaches you could try:

1. If you want to avoid the risk of people's first first impression of you being negative (a group mail or complaint about people taking your drink could seem petty), just stop bringing in fizzy drinks. It'll be cheaper and healthier to bring a refillable water bottle instead.

2. If you really want fizzy drinks and don't want to be seen as making a fuss, stick a large label on the bottle and write your name on it.

3. If you really want fizzy drinks and want to optimise costs and/or fridge space (I presume there isn't capacity for everyone to have a large drinks bottle reserved for their personal use), mail round your team saying you've been bringing in drinks and have noticed that many people enjoy them; would others be interested in sharing the costs of buying more?

Personally, I'd go with option 1. If you go with one of the others, be prepared for the possibility you're told that the fridge is intended for lunches rather than longer-term storage of snacks.

I propose two initial actions.

First, speak with your mentor/team lead/manager in private, raising your concerns about the soda disappearing and your desire to not make a big deal about it. Someone who has more experience navigating the company culture might be able to give you specific actionable advice (even if it's "ah, we usually treat soda in the fridge as fair game"). That you're asking here instead of a trusted mentor is a warning sign that you might not have one at your company. If there is none feel free to skip this step.

Second, do label the bottle with your name (I'd refrain from a possessive, just your name once in an obvious location). If it continues to drain or disappear you have established a "just cause"* for a complaint - failure to label a large container might imply it's for general consumption (vs diverse individual food items which obviously are not). I would bring up this plan when discussing concerns with the trusted mentor so you present yourself as proactive (never** raise a problem without a plan to correct it; doesn't have to be a perfect plan, just have something so you present yourself as proactive).

One possible reason an unlabeled soda bottle might be considered "fair game": if the company occasionally orders pizza with soda it would come in similar bottles, and it would be most reasonable to leave those (unlabeled, of course) in the public fridge for later employee consumption. This could have trained employees to assume soda bottles are leftovers from company orders.

* The point of a "just cause" is to prevent losing trust when taking an otherwise unacceptable action. In particular you want to provide sufficient reason for (almost) everyone to say "well, that wouldn't implicate me" and "I'd take action too". If you can, your action is socially justified.

** If the problem is big, complex, urgent, dangerous, and/or can harm the whole company, feel free to raise it immediately without a plan. Recognize that in some cases the problem is known and mitigated by something you were not aware of or the company/manager has deliberately chosen to accept the risk (perhaps because they feel the expected loss is less than the expected cost to mitigate it). In those cases you might lose some social credit, but less than if you have to explain later that you knew about the problem but were unwilling/afraid to report it.

Ask your manager about company policy for use of the fridge.

At some companies, anything not labeled with its owner's name and date it was put in the fridge may be disposed of during a periodic clean out. This is to keep people from leaving things until they go bad, and to make sure there is space for other users. It would be unusual to apply this to a bottle of soda, but depending on past arguments over use of the fridge the rules may simply be that strict.

In some companies, things that do not carry a name and aren't obviously personal like a lunch bag are presumed to be left over from a company event, and available to anyone who wants to claim them.

It is certainly better if these policies are posted. But they have often developed informally and nobody who knows them thinks to actually write them down.

Don't presume malice, presume misunderstanding. And remember that the misunderstanding may be yours. Or may not.

In any case, grabbing a marker and labeling your things with your name in large, obvious letters would be the obvious first step. Hopefully, even if you are running into a clean-out rule, somebody will notice that and think to tell you about that policy.

Don't complain to the internet. Ask your manager how to handle it. Helping you understand company policies and practices is part of their responsibilities.