bathroomplumbingtoilet
So my toilet only flushes down during the summer months. Yet during winter fall and spring it wont go down all the way. Can't figure out why. Tried a snake and every other means to unclog but I doubt its clogged.
I'm in Michigan. summers are usually 80 or a little higher. 50 60s in fall and spring. and as low as-1 in winter.
I've been a victim of this before. This is bad news.
In my (rare) case, the roof of my apartment building drained to the middle of the building and down the sewer pipes. During phenomenal downpours (twice in five years), the flow of water coming down that pipe was faster than the flow of water leaving the building. The water backed up to the lowest point where it had an exit which was my primary bathroom. It did so with such intensity that water was violently sloshing out of the toilet bowl, the stopper on the sink was forcefully ejected, and the bathtub was backing up at the same time. The only good news in all this mess is that it was fresh water.
Clearly, this is not quite your case. However, it is an indication of the same similar fact: you have a flow going in the wrong direction in your sewer line. Before the astonishingly violent discharge and water flowing everywhere, the toilet would gurgle.
Since it's a septic tank for you, you need that serviced now.
The reason the flushed water level is lower is probably that the siphon link between the bowl and the sewer line isn't being broken.
Even though you snaked the line near the toilet, it sounds like the line is still blocked or slow draining such that standing water sits in the line above the point of connection to the vent. Vent lines for toilets are often connected as shown:
Standing water above the reducing wye where the vent connects will cause water to be pulled from the toilet bowl as water flows down the line (such as when the other connected toilet is flushed). A flood when you flush both toilets indicates the sewer line is slow draining and cannot handle that much flow. Possibly the vent is plugged. More likely there is an obstruction such as tree roots infiltrating the line. If you have a septic system then it is time to pull the inspection lids, especially the one at the inlet. Check for obstructions such soap caked near the intake baffle.
Best Answer
This screams frozen vent stack.
To keep your drains flowing, you need to equalize the pressure. The problem is your sewer lines contain harmful gasses you don't want in your house. As such, you have a vent stack, a common drain pipe that allows gasses to vent out of the roof.
In deep winter (i.e. well below freezing, which is common in Michigan) what can happen is that the warm(er) water has some vapors that will head up the stack. Due to the extreme cold, the vapor condenses as it leaves the top of the stack. It then strikes the cold pipe, freezing to it. And now this makes for a nice perch for snow (image source)
There's a couple of things to do