Having not seen it, it's hard to tell you what to do but having cleaned  houses for over 25 years, I've gotten a lot of stains and water marks out using Bar Keepers (it's the same thing as ZUD, if you find that instead).

When we purchased the property two months ago the inspector had noted water marks in this area but said the readings were all dry and to monitor for leaks coming from plumbing from another unit’s second floor.

Of course not, so why would we use the high water mark of 2006 as anything other than a warning sign of prices being expensive again?

@Daniel Coleman One way to avoid someone posting your plans on the web as well as making it clear that they are looking at a bid set is to apply a big transparent red watermark saying "NOT FOR CONSTRUCTION" on them, a program like bluebeam makes adding something like this to every sheet a quick task.

Watermark with a tel. # all my pictures.

When they completed the demo we found a few water marks on the basement wall at the front of the house and the back of the house and towards the floor.

Dyllon Bobo at watermark home loans is pretty creative. 

You can get marginalized in the stock market, while in the housing market, you can only risk your initial downpayment if the house is foreclosed on or you simply cannot make enough rental money for the house.You must also pay watermark fees for an ETF fund.

Look for water marks on the drywall ceilings.

It is not leaking much at all and I cant find where it is even coming from.I starred at it 10mins and did not see a drop but the floor is wet.I believe it is leaking from the top under the ridge where the metal cover ends since i see water mark stains on the ridge and top half.My tenants said the city was messing with the street water lines and then they noticed the water heater leaking immeaditly.