On Thursday, January 14, 2016 at 7:31:48 PM UTC-5, wrote:
On Thu, 14 Jan 2016 14:55:40 -0700, Don Y
wrote:

On 1/14/2016 2:44 PM, TomR wrote:

But, like you, I think that if I used the pressure approach the issue of
trying to get the overflow plugged, plus the question of whether the
pressure would make the slip joints in the sink trap come apart, made me
hesitant to try it.

Then I thought, what if I took apart the sink trap, and I installed the
expandable pressure piece directly into the sink drain line, would that
work? I haven't tried it yet, but maybe that would be an option.

You still have the vent up to the roof to contend with. The pressure
solutions really only work to dislodge "dislodgeable" obstructions :
I find them preferable to resorting to chemicals as those are easily
overused.

But, if someone has made a special effort to clog your drain
(e.g., roots infiltrating the sewer line), no amount of pressure is
going to help. (a motorized snake with cutting head for root
problems)

If you really have roots clogging your drain, a backhoe is the more
appropriate tool. You can cut them back somewhat with a snake but they
will be right back. I suppose you could kill the tree but you can
still use the backhoe to dig out the stump and while you are there,
fix the pipe ;-)

I just did something similar myself with a mini Kabota.

I use Root-X twice a year. Haven't had a blockage since I started doing that about
4 years ago. I've had the line scoped and I've seen the problem. Roots are entering
the top of the pipe at a junction between 2 sections.

$5K to have it lined, not sure of the cost to have it replaced or $75 a year to introduce
2 lbs of Root-X through the clean out in the spring and fall. I consider it just another
maintenance item.

rootx.com

Others have suggested rock salt but the beauty of Root-X is that it foams up, fills the pipe
and coats the roots that are coming into the top of the pipe. Salt water will only contact
the roots that hang low enough to reach the flowing water. Since low roots aren't my
problem, I need something that gets the ones on top.