Water bill is 400% higher then last bill, faulty meter or leaks?

[Henry Lazerow]

I have a 4 unit in Rogers Park that received a water bill over 400% higher then last billing period. The building has been fully occupied with same tenants all year so I do not see any actual increase in usage. Is this likely from a leak or a faulty meter? What's best course of action disputing the bill or areas I should check for leaks? 

Thank you, 

[John Warren]

Henry I normally check the toilets in buildings like this. Even newer toilets can have small parts fail that cost big money. The ACE hardware by me in Berwyn actually has free die tablet tests that we use. You throw them in the tank and then you can see the die in the bowl if the toilet failed. You would be surprised at how many newer toilets have significant leaks and also that even very good tenants won't notify you because they don't notice.