Essentially, the landlord was not respecting the tenant's quite enjoyment of the premises - while you may own the building, when you lease a flat, it is the tenant's space and, as long as they are not doing anything illegal, damaging the property or putting others at risk, you have no real say how they enjoy the property.While the amount of the fine seems a little excessive ($6000 to each tenant), it does show a situation that escalated unnecessarily.

It could be that one of them is missing something, it could be that another is including something twice or even unnecessarily.

There was no concern for harm for brushing teeth, just ingesting large amounts of water with limits outside EPA limit can be harmful over time. 

If my properties were close by I’d always be worried about them or checking on them (probably unnecessarily).

They are often quite simple, have few parts, and can be easy to troubleshoot and even do some routine maintenance and minor repairs yourself.I've had to deal with a couple furnace issues in the last year, in both cases a bad logic board was the cause, and we only discovered this after having multiple HVAC companies come out and assess the problem, struggle to find the root cause, often replace other parts unnecessarily, and ultimately shrug their shoulders and recommend a full replacement at $5k+.In one case, I went online, bought a logic board and installed it myself to fix a furnace that wasn't working consistently.

For example, lead paint should never be dry scraped or sanded as it creates lead dust which is then inhaled or ingested.

It will prevent many people unable to buy a home from doing so, it restricts the way people can sell their property unnecessarily, and forces people to use (and pay for) services that they dont need (apprasials, etc).

Search through Bigger Pockets Members list and look for members in your area who have information associated with their names that is related to what you are seeking.Involving yourself in forums, blogs, podcasts, and webinars will avail you opportunities to engage with members while ingesting informative information.Consider spending 30 minutes for 40 consecutive days on Bigger Pockets.

I have seen many of these go bad unnecessarily.

I used a realtor for both my previous properties, but listings seem few at the moment and I need to learn how to approach each potential buy independently to avoid dishing out potential profit unnecessarily.