What's the easiest way to make a lot of decent coffee?

[Lochroy]

Well, think 20 cups rather than two but not 200

I'm organising an event soon and I don't drink coffee, but people seem a bit sniffy about instant. I own one cafetière (but don't actually know how much coffee to put in it when I do use it!!) and have scope for purchasing or borrowing items from other organisers. What's the easiest thing to do? Just borrow a couple more cafetières?

It makes fairly strong coffee, some of the older folks find it too strong and top it up with hot water. Maybe they are only 1 litre pots, I'm not sure.