Our insurance company wanted us to replace both water heaters before insuring our home but ultimately okayed it based on that they both had drains and we already had a warranty transferring on the home.

If its not either one of those I'd fo a water test on the plumbing waste. 

Generally tenants pay all utilities, but its very common for landlord to pay water around me.

Examples: I take a refundable pet deposit instead of a non-refundable one or a monthly fee, I currently pay the whole water bill without taking money from tenants because the duplex is watered together (I will eventually get a separate meter but the outlay is more than I want to pay right now) assuming it doesn't get out of control, paid for the new doorknobs on the bedrooms because the tenants requested locks despite the lead tenant saying they would pay for it, planning to replace the microwave hood simply because it's louder than it should be though it still works, etc.I'm probably losing out on a minimum of $100 monthly.

It has copper water lines with lead solder joints.

Bad deals flow here like water.

Chesterfield announced world's biggest water/surf park yesterday too.  

My hot water heater has a leak, I had a plumber look at it and they couldn’t find the issue.

Only had to Paint walls white, clean carpets and replace refrigerator What was the outcome?

Replaced the water heater.