I have a leaking oil tank. 

I'm a gc, but had a buddy call the other day asking about a boiler leak, as well as some electrical work.

In a couple of places around the old chimney the plaster had fallen because the roof was leaking around the ceiling.

I haven't had a leak since!

Too many people in a place can cause that.3) Look in the attic and crawl space for leaks/standing water. 

The home has decay on the corner trim on the roof, shingles are near the end of their service life, leak in furnace, and some pretty bad electrical issues.

It also increases the likelihood of a hose being hooked up wrong and a water leak.

.
* Roofing cannot leak and must have at least two years of life remaining.
* Attics and crawl spaces must have vents and be free from damage.
* No active termite infestation.
* The property must be reasonably free from environmental hazards, odors and excessive noise.

Also immediately buy and set a lease addendum that you need working leak detectors in every leak able spot (under bathroom and kitchen sink vanities, by dishwasher, by washing machine, by hot water heater, by ac condensate line, anywhere basement might flood ( near sump pump).

Shouldn’t the landlord work to protect their investment by fixing the leak immediately after it was identified?