How much drink would you allocate for a party?

I'm organising my friend's hens night for this Saturday & am worried I don't have enough drinks. I am providing soft drink & they are providing their own alcohol if they want. There are 18 women. Two are pregnant so won't be drinking alcohol & four others won't drink either, or will have very little because they are driving home. We are starting at 1pm with pampering treatments & then going all night as a big pyjama party. I have 13L of soft drink and am thinking it might not be enough. Should I be catering for at least a litre per person? What would you allocate?

I'd be thinking that that would be enough soft drink but I am wondering about juice and milk for the morning.
Mind you - I work on the theory that if someone brings a bottle of rum thinking that they will be drinking rum and cokes all night they would also bring some coke IYKWIM.

I would organise it as around 4 drinks per person, 4 drinks would be around a litre, so yep I reckon a litre per person, and maybe a couple of litres extra just in case?
It's better to have too much than too little!
:)

I always buy a bit extra than what I think we will need - if there are leftovers, so be it, but if there is not enough it is annoying and a hassle to have to go to the shops to get more. If we are having a lot of people over we tend to buy a carton or two of cans of soft drink, then we will have maybe a big drink bottle filled with punch or cordial or even just water as a back up. Extra milk is handy too, for cuppas.

I would definently work on at least a litre per person...plus extra just in case. You can always store any extra for future parties, bbq's, BB meets, LOL.

Aaaah yes juice & milk for the morning, good thinking Muppity.

Off to the shops for me again tomorrow!

i think a litre per person is about right.. but still have back up! what about flavoured mineral water as well.

i'd work on a litre or more per person - and have LOTS of water available (not sure of the quality of Sydney water, but we make sure to have bottled water when we have drinkies) - if you have people drinking, it's good to have water for them over night or early morning (or if like me, i drink a good half litre before sleep to flush out the hangover). for those that aren't used to lots of sugary drinks, they might have a glass of softdrink and then a drink of water in between...

Don't forget your tea & coffees! And cocoa for the PJ party ....

I generally work out what I think I need (I go by the alcohol units recommendation - 1 drink every hour) and then add 50% so I don't run out.

If you get ice and crush it in blender etc, it extends the drinks as well as being a bit spesh :)