Our condo's (12 units, 2 buildings) water usage went from $300 to $3000 in a few months. We don't have separate water shutoffs to test each unit. Nobody's reporting any visible leaks. Any idea how to proceed? We are going to go bankrupt at this rate.
You could install flow meters on each unit and bill them separately.
I seriously doubt that this is a small-scale leak like a running toilet or a dripping faucet. If a 12-unit water meter is reporting 10x the normal usage, that's like 100+ apartments' worth of water that's unaccounted for. That would be hundreds of thousands of gallons of water per month. There's no way it's just dribbling inside some wall.
(I assume this isn't something seasonal like an irrigation system for a golf course, or filling up swimming pools...?)
My guess is that either your water meter is broken or there is a serious break in your water main. Either way I could call the water company immediately.
(You might also double-check the bills to make sure you're really being billed for a ton of water and not something else like equipment fees or late payment charges. The bill should tell you how much water you're being charged for, usually measured in hundred cubic feet, "HCF".)
Is it possible that they were billing estimated usage which was too low for a long time (many months or years) and then when they finally sent someone to actually read the meter they needed to do a big adjustment? Was the usage really high more than one month in a row?
Without separate shutoff valves installing individual meters would require knocking down walls, which is not feasible in a condo.
The best option seems to be to hire a leak detection company.
Turn off the main valve and see if the meter is still turning. If it is...you have a leak underground.