I had Major Drain come out and hydrojet my sewer line. Two years ago the sewer backed up into my basement. Very expensive. My house is 70 years old and surrounded by huge trees. Yup, it was tree roots. At that time I was advised to get the line water jetted every 3-4 years. The Major Drain guys were on time, sent a camera down the line to the city sewer, and showed me the new tree roots. They are gone now and I have some peace of mind. So now instead of every few years I’m going to hydrojet every TWO years, as the MD guys recommended.