Buying park with 40+ septic systems on 1:1, older system. Owner says they haven’t had any failures.
2)Any recommendations for DD (not spending $30k to drain and inspect them all).
3)Would our insurance help with any individual septic replacement?
I’d be stunned beyond anything if any insurance company would ever insure this type of event.
Agreeing with Zepp on this.
As a couple alternatives though would be to A) visit the local health department and inquire if there have been any failures and/or repairs at the park, who did the work (and then visit with them and see what their thoughts are on the park system). Or B) you could try to walk the park without the seller and ask a couple residents if there have been any issues. With only 40 spaces everyone would know if there were any issues.
One other thing you could do would be to pay for a few tanks to be opened up and pumped. Homes with big families maybe. Any reverse flow out of the drainfield will give you a heads up.
Some septic systems depending on the soil and construction can last decades. My folks have one that is 60 years old and brother and I flushed all kinds of stuff into it growning up. 
You can do a load test.
Open up the lids and measure the levels of septic. Run a hose into the tank for 30-1 hour. Remeasure the levels.
If the levels rise, then you have a drain field issue.
Also, you can inspect the tanks and look for signs that the tank is backing up. If you see a “ring” of debris that is higher than the static level of the water, that is a good sign that the drain fields are not taking on the water anymore. Also, check the baffle on the exit side. If it’s under water that a sure sign of bad things to come.
We operate three, soon to be five, communities on septic all either 1:1 or 2:1. Several things here:
Call environmental health and request all historical permits they have on file. This will tell you where they are, what they are, and whether they’re functional as far as the county knows. This should also include any repair permits that have been issued over the years. You should also ask to speak with the EH guy who covers the territory the park is in. He’ll know the details if there are any REPORTED ongoing issues.
Prior to each purchase we spend the money to dig, pump, and inspect each one. This really shouldn’t be 30k. Going rate in our area of NC is 250-350/tank. This will uncover any structural issues with the tank, tell you if you have toilets running, tell you who puts grease in the drains, etc. Even if it is 30k, that 30k could theoretically save you from a huge mistake if you’ve got a bunch of issues and/or could give you grounds to retrade the deal. I got a purchase price reduced by 200k on an 800k purchase because I was thorough on my DD and retraded.
It sounds nuts but we’ve bought parks with known septic issues. Mom and pop almost never have a pump and/or maintenance schedule. We bought a park several years ago with two “failing” drain fields. One pump schedule later and we’ve not had any issues. We pump every 2-3 years depending on the park and if the systems are shared or individual. We typically find that most issues are self-inflicted i.e. grease, tampons, wipes, running toilets, etc. If we find issues, the tenant gets the bill and you lease should state this.
In our experience, the biggest threat to septic longevity is groundwater. Look at how the property drains. Does it drain toward any tanks? Does it hold water or does water pool near any? Is the park in a natural low spot? If there are any low spots near septics, have your septic contractor dig you some 3-4ft deep perc holes near (within 5-20ft) the drain fields. If the perc holes fill with groundwater while he’s there pumping and inspecting, this may be cause for concern, especially if there is a layer of clay or bull tallow in there or at the bottom.
How spaced out are the homes? Do you have room for repair fields if one does fail? If not, you’ll be moving a home out and using the pad as the repair area. Its not ideal, but even this isn’t the end of the world. If there’s a chance you’ll lose lots due to septic failure, discount the price accordingly.
Don’t let septic scare you, but don’t be cheap either.
This is legit advice from Jake and I concur with all of it.