Coffee for 30 people (off the grid)

Army style  boil 6 qts water put coffee in chinoise with cheesecloth, pou boiling water over groundsin large pot. mix once disgard drounds. and keep hot on gas stove. Or you can tie grounds in apron and make a large tea bag and let steep in boiling water.

You can do "drip" in several large brewers, with water heated on the stove.  Similarly, you could make a "cold brew" base, such as "Toddy" and add hot water.  Or, buy several large French press pots.  One of those methods or some combination of them is probably best. 

They way you'd use cold brew is to brew a base concentrate, and store in the fridge until wanted.  Once you've got the base, it's no more trouble than making instant; just dilute with hot (or iced) water, at a ratio of 2 or 3 water to each part base.   Cold brew is a lot better than instant, and truly awesome for iced coffee (good for cooking too).  A commercial sized "Toddy" runs around $90 and makes enough base at one time for around 8 gallons (128 8oz mugs) of regular strength coffee.  Each max batch takes around 5 lbs of grounds.  You'd probably brew two batches per week. 

Vac Pots are great, but they're expensive. 

"Army" or "Campfire" coffee -- brewing loose then straining though cheesecloth -- might be fun when you go camping, but it's wretched compared to even inexpensive but OK instant coffee like Nescafe Classico. 

Using cheesecloth for a drip filter is not a good idea.  Too loose, Lautrec.   If you're going filter pour-over or drip, get a bunch of Chemexes or Hario Woodnecks or something.  I vote Chemex because your situation sounds so sixties.  A "10 cup" (50 oz) Chemex is around $40.  If they were all you were using, you'd want at least four.

A 10 cup "family size" propane burning brewer runs around $100.  I think there are also small commercial size (about right for you), propane fired coffee makers.   Probably expensive, and I don't know who makes them.    

No matter what method you choose, use good beans, store them correctly, grind the right size, and don't grind until just before using. 

Hope this helps,

BDL

My error mixing defined by me means the first coffee that comes thru will be the stringest the same as in an electric drip pot home so you want to mix all the liquid dripped  coffee together to get an equal blend throughout.  With apron technique water is not coming into direct contact with grounds where  other drip method is.  I have used this method as have many others before me to make hundreds of cups IT WORKS. Instant coffee tast like instant coffee with a slightly metallic taste .(I for one refuse to drink  instant of  any kind)  Its your choice. I am not 'brewing loose or pouring wter over grounds then straining, I am in essense using same drip technique you use in a Mr.Coffee. grounds go in cheesecloth lined chinoise water poured over.

i think i too woud brew it in a pot on the stove, then dump it in a self contained sterno coffee urn to keep it hot for duration of service. cost to make, cheap, cost to keep at temp, very cheap. And I THINK these urns brew, but it takes a lot longer.

You can use any type large strainer. Just make sure you use cheesecloth and before you use rinse the cheeecloth in water to remove any starch if any.

I wonder why no one sells cheesecloth liners for coffee makers. 

BDL

You Know what you can use ,you can use the cones filters to clean and filter the oil from fryers also ,use it with a china cap and pour the water over ,good luck