OK, I agree with the above. Nothing wrong with septic as long as you keep it maintained. A great way to recycle your water (no flow through waste as a muni system) and you are independent of regulators and charges as long as it's functioning and historic. Same for well.
I'm on a river and have septic (1930's) and two wells. Kitchen well dug to ~70 ft in the 1940's - sanitary seal 20 ft. About 75 feet from one leach line. More than 100 feet from the other. They diverge in an L pattern. Second well is garden (wife has registered culinary garden - restaurant trade) and it's 120' deep with water table at 20' ... Sanitary seal for well number 2 is 50 ft.
Point being that is it's all maintained well, these systems can run well into the hundreds of years w/o trouble.
So, if you like the property, buy it. Live there and do incremental upgrades as time and budgets allow.
last year was first major repairs to septic in 85 years. Pumped and new lid installed with new rim seal and risers. One leach leg dug (by hand, two laborers) and reset with new drain rock, existing tiles, and new top seal. The old top seal had failed and dirt had in-filled the drain rock. Total cost was less than $3,000. Contracted teh tank lid and pump out. Hired the day labor to re-set the first leg of the leach field.
Works better than ever. In a few years, I'll have a couple of laborers dig up leg #2 and re-set it the same way. It'll be good for another 100 years at that point. Have the tank pumped every 20 years or so to get the "un-digestable" solids out of the tank.
Wells need new pumps and controls occasionally. New pressure tanks maybe every 30 years or so. Depends on if you do maintenance on a regular schedule ... The less maintenance, the more you'll be replacing stuff ...
Muni systems are why we have water shortages in the USA. They are almost all pass-through systems, and send their waste down stream. Require new water from upstream.
Well and septic systems are much better balanced. Septic keeps waste in top zone until it can be digested by bacteria. It'll slowly settle into the water table, but it's a decade long process. Much more self reliant system. Well and septic systems that are working well, are good almost indefinitely
And, if you are worried about bacteria in the house water, use an in-line UV system at least 4 ft long. It'll kill anything in the water - no taste or pH changes to be worried about. AND, use copper pipe to feed the house because copper will keep all the bugs away. There are very few bacteria that can survive a copper rich environment. Copper pipe is mandated here by the County Building Department, and we're glad it is