The 1 pieces are great because there aren't any seams to caulk/that can leak.

It doesn't leak. 

It can alarm you to any potential leaks. 

An AFCI  device senses the delta between power and in neutral in an attempt to detect an arc that's bridging air space.Most AHJ'S here now require pretty much every circuit to use a AFCI/GFCI combo breaker.Those retail circuit seekers (tracers) from the retailers aren't very good, a good budget one is north of$500, good one's are $1500-$3k

Personally, if the pipe fittings were not leaking, and did not show signs of significant corrosion, then I would probably leave them alone until there was an issue.

Common problems are sewage backups, mold, infestations of rats, and other pests, faulty wiring, roof leaks and it violates the city’s building, health and fire code poses health and safety risk.

No leaks from roof or in basement.

Deck is falling down (covered by HOA) but has resulted in an ongoing ceiling foyer leak.

If they find the tank has leaked the costs go up big time .

Please remember it is not your responsibility to play detective and spend hours digging into her past.