I have reviewed how can we prevent theft of food from shared fridges by coworkers and whilst similar I think the differences warrant me posting this as a separate question.

Me and my team (12 in all) share a tiny communal kitchen space with another team consisting of 8 people including their manager. Both teams work in completely unrelated disciplines and have no contact between them apart from the simple fact that we’re based in the same building and share a kitchen.

Each team has a small fridge, for people to keep milk/sandwiches/lunch etc. I buy a couple of pints of milk each morning which generally gets us through the a day’s tea drinking. Unfortunately, over the last 3/4 weeks the milk has been used by the other team quite extensively, to the point where upon checking their fridge they have none in there and by midday ours has been completely used.

I’ve been off for a week and returned on Monday to find what I can only describe as open warfare between the teams, generally comprising of blanket attacks of passive-aggressive (through to openly aggressive) notices and post-its being left in the kitchen. Both sides are contributing to this, I understand it started with a ‘Development Team only milk’ post-it and has now escalated to what are (admittedly amusing, but) unproductive insults.

I put an immediate stop to my team leaving notes etc. however the ‘milk theft’ is still ongoing. I’ve spoken to my counterpart in the other team and without repeating the conversation verbatim essentially explained that whilst I’m in no way suggesting that my team are blameless in the great note-war that’s been ongoing that I understand their frustration at what is essentially theft of their property. I was left pretty stunned by his response which was along the lines of ‘I don’t use milk, I can’t tell them what to do, they’re not children’ and a general lack of any interest in working with me to resolve the situation.

I cannot take this any higher, myself and my counterpart in the other team both report into Exec level (different directors) and I refuse to take such a petty matter to my boss who is genuinely too busy to be bothered over something so small. In fact I feel stupid posting this on here but I’m literally at the end of my rope. Nor do I really want to stop buying milk for ourselves, I shudder at the thought of us spending a day without tea and honestly don’t see why we should have to in this situation. As we work in an austerity measures ridden Public Health Service there is no possibility of the organisation footing the bill for anything which is the reason I buy it for my team in the first place.

How can I influence my counterpart to address this matter with his direct reports?

UPDATE

I may have missed a few details in the original post (in the interests of trying to keep it from essay length) such as;

• I raised the option of having a shared milk fund about 3 weeks ago (when this had first started) and was pooh poohed by both the other teams manager and its members on the grounds that they had 'only used a little bit of the milk' and it wouldn't happen again.
• There is no confusion whatsoever over who has bought the milk, I made it clear at the same time I discussed a shared fund that this was milk I bought out of my own pocket for my team. We literally have to beg for things like stationary due to the reduction in public spending over here so there can be no doubt that anyone is under the impression this is being paid for out a budget funded by the tax-payer.
• Moving the fridge is impossible, whilst it's small it is about waist height and we've no spare plugs for it to be plugged into regardless.
• We don't really have the option of buying a mini-fridge due to the lack of plugs already mentioned and due to the fact that it's a hospital building everything has to be PAC tested by an external company for health & safety and insurance purposes (public sector bureaucracy).

I'm going to plump for keeping the milk out of the fridge for the next week and in our (entirely separate) office. Unless they actually walk in and try to take it, in the extremely unlikely possibility of this happening they'd be turned away politely but firmly, this will prevent them from using it. I appreciate it's not going to resolve the simmering hostility between the teams but honestly don't see why I should be further out of pocket as a result of petty thievery and the poor management of them by my counterpart. I don't resent for one minute shelling out for my team, it's a small thing on my part that keeps morale up in an incredibly stressful environment but at £10.00 a week (about $16 I think) I'm not doubling it in the interests of appeasing another team with no real belief that this would change their behavior.