Tenant should only be responsible for the portion of "normal" water usage.
Unless you can prove that tenant knew *continued* and *significant* leaking issue without reporting and completely ignored it. But in this case, they already attempted stopping the leaks that were visible to them.
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It has a lot to do with *actual* cause of the leaking as well. If the leaking was found mostly underground, there is no way you can blame the tenant.
Yes, landlord is a risky business; one may not always able to transfer a blame to tenant.
What about the insurance coverage?
Why the water bill is under landlord's name to begin with?
