things can work well one day and break the next.i think you did all you could do. i'm not sure if there is a pressure test for sewer systems or not. i know the last house i bought, there was 99.99% saturation on one of the walls. i was sure that there was a leak in the pipe behind the wall. i called out a leak specialist and he said that he could detect even the smallest of small holes in a pipe. the saturation ended up being from the window sill being sloped and the water ran into the wall. easy enough fix.the $75 charge to have the leak specialist eased my mind, but in your case, if there wasn't even a faint leak or crack, i don't think you would have had anyway of knowing beforehand.

Is this area still worth looking at or is it over saturated with STRs? 

If you are in a market that is saturated with investor and one where there are many new and rookie investors I can tell you that there will be TONS of people mailing the standard "yellow letter" and yours would just get lost in the shuffle.Here in the New Orleans area, we are completely saturated with investors.

I would say to avoid any markets that might be over saturated with investors.Feel free to look at:The Best Types of Markets for Profitable Turnkey PropertiesandWhat to Ask When Working With a Turnkey ProviderGood luck!

Some people told me it is a bad idea to invest in Portland as it is saturated market.

It's also important to look at actives because if there is a market with a million actives then you're going to have a lot of competition and the market may be very saturated.

Is the area overly saturated with investors now? 

@Jeremy RowanA friend and I were considering doing some direct mail for the purpose of flipping but reconsidered after seeing the saturation of the market in DFW.

at some point massive saturation in a market like Texas had to happen.. and I think one other thing.. is this prediction that mellenials don't want to own they prefer renting..is not coming to pass as predicted..

Depending on your location the mass lists that you purchase could potentially be very saturated.