Since that's not possible in this case, is there another way I can gauge sewer-related risk of a specific property?

I'd lean on your agent to put pressure on them.

A few bad apples raise your blood pressure and cost you money.  

I believe this added supply will put pressure on rental prices for 4-plexes and apartments.

if you're forced to take his deal or nothing, then walk. if you're feeling some kind of social pressure to take a deal you don't want for ANY reason but especially if you think he will only help you because he's making money on you, WALKsounds like you just don't want to rock the boat which I understand, but that's a bad habit to get into.

And the statement about feeling shady implied you were feeling pressured, either internally or externally, to do something you didn't really like.Just my 2cents.Secure funding, either conventional or hard money, then put it under contract.

I personally have spent more than 25 years in the petrochemical industry and have had to wear fresh air respirators and full chemical suits in numerous pressure vessels and towers that have had toxic or inert atmospheres that were considered IDLH "Immediately Dangerous to Life and Health", and I still don't have the time nor the desire to worry about how someone's hair or lack thereof would impact whether or not I could work for or with them.

Hence, there could be some pressure on market rents.For Insurance try: Ramey King Insurance OR BenchmarkFull disclosure I have no affiliation with these insurance brokers nor have I used them.

If you decide to go in this direction, I'd suggest reaching out to several companies in the area, asking them questions, gauging response times, online capabilities, reviews, and current inventory of homes.

I would like to know how much capital I should have saved up to get a gauge of where I am at currently prior to going through with an  investment property.