Question about plumbing. Currently at a certain point in the wash cycle when running our washing machine water is backing up in our kitchen sink. I'm curious whether this is a clog problem or something related to our septic system.
Impossible to say without a whole bunch more info.
Our neighbors have a similar problem and it has nothing to do with their septic system.....or the venting......or a clog. Their problem is due to the fact that the drain line is undersized for the output of modern washing machines. The 1 1/2" branch drain can't take the water as fast as the new machine puts it out and so.......the water backs up into about 20' of adjoining pipe and emerges just a tad from their kitchen sink. (Everything worked fine with the old machine)
This is not to say that your problem isn't related to your septic (although not all that likely if everything else functions properly....including toilets)....or an impeded/non-existant/undersized vent (possible)....or a clog/partial clog in the drain-line (posssible also).
On-site diagnosis would be best/most reliable.