Plumber question

Went to lake house and discovered that the toilet doesn't flush good. Sometimes it requires plunging. We have a big flush volume type toilet. Sinks seem to drain properly. Toilet was installed last year with a new shower. All was working well last year. We haven't used the toilet in a couple of months.

We are on a septic tank.

The sinks seem to drain well. I fill the sinks up and they drain as usual, not slow, not fast.

The house has no sewage flush plug. Built in 1970.

Any ideas before I call Roto Rooter?

Not a plumber but.... It could be roots growing in to the septic lines. Your best bet might be to have them run a camera through the lines at the house all the way to the septic system.

Another common one (with toilets) is: IF PVC was used was it an outside coupler or an inside wall coupler? What I mean is, does the pipe go inside of the toilet flange (creating a lip) or does the flang go inside of the pipe (leaving a straight wall)? Another location is the 90 or 45 coming off the pipe. Is it a street 90 going inside the pipe or a traditional 90 where the pipe goes inside the sleeve? The reason I ask is the ones used where the pipe goes inside of the 90 or flange tend to have sharp edges. Depending on how they are cut and who cut them, some guys clean the edges before inserting, some do not. For PVC (dealing with toilets) I've found it better to get the ones that go inside of the pipe.

The same issue can hold true for the old cast type systems. Sharp edges inside of the pipe tend to hold on to things. Over time, it builds up until eventually, there is a blockage.

As you are saying you have not used it in awhile, I would suspect one of two things however. The first would be easy to find with a camera system... Roots growing in your lines exiting the house and going to the septic tank. The second would be worth checking. Your vent stack pipe. You very well could have a blockage in your main vent stack that is causing your toilet and other systems to not vent properly and dischage the water.

I know you said your sinks don't drain fast or slow. I'm betting that because it was an older house/camp/cabin, there isn't proper venting for the sinks. There is a maximum distance you want to run stuff from the vent stacks. After that, the vent stack becomes null and void as the recepticle (usually a kitchen sink) doesn't get proper venting. There is however an easy solution. There is a product called "Sure vent" which allows you to connect it under the sink and allows the sink to vent properly. To install, take the stub pipe out of the floore and attach a sanitary T. To the center of the T, run your trap to your sink. Put another stub pipe on the top of the T and install the sure vent. Make sure the dust tape is removed. This will help with venting. When installing the sanitary T, make sure the center sweep goes "Down". There is a right and wrong way to install based on how you want the water to flow.

Hope this gives you a few ideas on what to look for. I suspect roots in the lines but also venting.

For a guy who isn't a plumber, I'd say you got this. Good job.