Toilet Running/Leak Detector?

[Achi Adamit]

Just had a $5k water bill due to a running toilet in an apartment that brings in $520/mo. Tenant failed to inform me or the management company that the water has been flowing for months.

I've looked all over and found the following device sold on Amazon: https://www.amazon.com/nth-Solutions-LLC-LeakAlertor-6000/dp/B01N3ARQOL/ref=sr_1_1?keywords=leakalertor&qid=1570370732&sr=8-1

Has anyone used this or anything similar to stop debilitating water bills?  Alternatively I will have the management company read and submit water meter readings on a monthly basis.

Tenant admitted to having known about the water sound - do I have any recourse based on that?  Unfortunately there's no lease that we're aware of since we inherited this tenant.