I hate plumbing. I'm a pretty handy guy, as far as home repairs. I can do minor electrical, carpentry, painting etc., but plumbing has to be by far the worst. To further clarify, drains and such.

We moved into another house about 2-1/2 years ago. This house is almost 50 years old, but has been updated / modernized over the years by previous owners. However, plumbing issues have been our biggest issues.

Last December we had to replace a broken septic tank inlet line and have some field lines re-connected, to correct an improper installation done just before we bought the house.

More often, and just recently, the kitchen drain line has been troublesome. It is the longest line to the septic tank outfall (roughly 45-50 feet), and unfortunately doesn't have much slope to ease drainage through it. We have screens on the drains to catch particulates, and don't pour grease down the drain. Yet this line gets slow or stopped up about every 2 months. Some of its issues might be left owner from previous owners.

I bought a 25 foot drain snake that I can connect to a drill, and I can access the cleanouts in the basement. The snake length allows me to go from the kitchen drain to the outfall, accessing the most downstream cleanout. I have snaked the drain from the sink drain and all the way to the outfall, but it's still clogged as of this morning. I am going to re-snake a section that might contain the issue tonight.

In the long run, I'm either going to have a section replaced to add more slope, or add a small pump.

First world problems, I know.

You need to have a plumber come and scope it to see what is going on.

I did this recently for a gutter downspout that went into an underground pipe out to a lateral line near my street and the plumber found that it has settled over the past 70+ years and was basically running uphill and the water was backing up right at my foundation during heavy rains.

He put a snake with a camera down there and saw exactly what was going on. It's finally getting replaced next week at the cost of $1900...OUCH but he's got to dig up 40+ feet of this and also going to tie in a drain at another low trouble spot nearby

What I did one time, was bring in a garden hose and stick it in the sink output with a rag around it. Turn on the hose and let it build up pressure. It will only go so high before it comes out the roof vent.

^^^^
Oh that must have been fun!

OP here -- just after I posted this, I had a thought - the vent pipe might be plugged. It's relatively close to the eave, so I might try to snake it when I get home.

Check your toilet

OP here. This may be a little long.

Luckily the vent pipe was close to the eave. Had to trim some bushes to get the ladder in place, but that's something we do anyway through regular yard work. I dropped the pipe snake down the vent pipe and felt some resistance. Turned on the drill and worked the pipe snake back and forth until the resistance was gone. Then I let the pipe snake go its entire 25-foot length just to be sure, then reeled it back in.

We had some standing water in the kitchen sink. Strangely, it didn't appear to go down. So I went into the kitchen and fed the pipe snake back down the kitchen drain cleanout its entire length, in case I was pushing a blockage. I went to the basement and cracked open the last cleanout before the septic tank outfall. I could hear some air hissing, and when it stopped, I carefully opened the cleanout. No water behind it, and I could see the pipe snake from upstairs in the line. Closed the cleanout. I go upstairs, and the kitchen sink is now drained. Hmmm. I went back to the basement, carefully opened the cleanout again, and ran a 10-foot cable that I use for bathroom drains into the line, and felt some resistance about 6 feet in.

So, I reel in the pipe snake upstairs, and then put it into the basement cleanout and start turning it. Yep, apparently a blockage I was pushing. I finally got it to the septic tank outfall, which is a larger pipe. Pulled the pipe snake out, closed the cleanout, and went back upstairs.

Turned on the dishwasher and ran it on "hot wash" settings. It didn't back up into the sink when it discharged, like it would sometimes in the past. Let it run an entire cycle and it appeared to be fine. After that run, we refilled the dishwasher and ran it again. This time some water did back up into the sink, but drained away after a few minutes. This dishwasher has 4 discharges through the wash cycle. Subsequent discharges 2 and 3 had some backup into the sink (each smaller than the previous), but discharge 4 did not. So I don't know if there was a maybe an air lock / bubble in the line?

Anyway, I'll watch it over the next few days and see what happens.

Did I mention that I hate plumbing?

You really need to get that scoped.

I had tree frogs getting into the 3/4 inch vent pipes I had on the plastic barrels I used for water storage.

You never know, maybe a squirrel storing nuts.