Monthly operating cost will vary significantly if there is much treatment taking place. However annual lab should average $2500.00 many of the really expensive samples are on a 3, 6, or 9 year sample cycle so most years it will be sub $500. Two main costs are operator and electric. Operator if you can find a good one my guess is $400 to $800 per month for a once a week onsite type deal. Electric $150 to $250.00. If you have treatment: chlorine, ph adjustment, iron, hardness removal… you have more costs obviously.
Capex is really dependent on the set up. You may have one well pump $6000 (10 year life) and one booster $3000 to $6000 (5 to 8 year life). Most likely there will be a pressure tank or two and maybe a reservoir. You could have a $2000 (2000 gallon plastic) reservoir or a $150,000 (40,000 gallon steel) one. I see it done both ways. Would need more info to ball park capex on them.
If your well is working good, keep it. I have had my Park for 40 years. Original well was only 50’, started getting Nitrates in it, so drilled one 80’, water was full of sulfur, drilled one 335’ water seemed fine, but tested high for manganese and iron. ?State gave me a grant to hook to City water. I spent a month running 1500 feet of new water lines and split my system. The City water only goes inside the mobiles and all outside watering remains on my wells. Any one of the 3 wells will handle the outside watering. This keeps my City bill under 5,000 gal a day and around $500. in the summer, my well use is 24,000 gal a day, so you can see the savings, and no more testing, no more certification and the tenants gladly accepted a slight increase for City water.
Septic is ALWAYS an on going battle. Cooking grease was my main enemy. I put out a letter to all tenants to stop pouring grease and oil down their sinks. Many had never thought it was a bad thing to do. This alone doubled my times between pumping.
Here is a secret I learned that is worth it’s weight in gold. Forget those high priced enzyme treatments. Equal parts of Yeast, brown sugar and baking soda, is far superior. My septic pumpers were amazed at the difference. Yeast is bacteria, it feeds and multiplies on the brown sugar and the baking soda provides the extra Oxygen it needs to survive.
Every 3 months mix a pound of each and flush it. I also added aeration to the gray side of my tanks. bacteria needs oxygen.
When cleaning lines, pour in baking soda followed by white vinegar, followed by hot water. works well and the septic tank bacteria gobble it up.
The main tank is 7500 gallons. With about 100 people on it. (people, not mobiles).
the concoction works REALLY well and is really cheap.
Sams Club has all the ingredients in Bulk, Costco has them at their commercial store, not sure about regular stores.
I have gone from pumping this tank every 6 months to every 2 years, and it is not bad at 2 years. Also having a vent pipe in your leach field is a big plus, it needs to breath.
Best of luck: Bob