I live in a 16 year old townhouse with a basement and two levels abouve ground... recently, the basement toilet gurgles when the washing machine (also in basement) is draining... then the gurgling led to lint backing up into toilet. Now, I went down stairs to find the toilet had overflowed, and was in fact full of grayish blue water. I don't smell sewage... seems to be washing machine backwash. Do I need major help??
Thanks, John

You have a clog, call the plumber and have them use a cable [sewer machine] to clear the drain. If it happens again, have them also run a camera down it.