Toilet problem

[Norman D]

I have a split-entry ranch home, which means that the ground floor varies from ground level to about 3 feet below ground level. Ever since I installed a toilet on the ground level on an existing waste system setup there has been a tendency for the toilet to either back up or go down slowly if it's flushed when the washing machine is on, or for awhile after it shuts off. The washing machine drain pipe is located a few feet downstream of the toilet. I've had the waste line Roto-Rootered several times all the way out to the sewer connection at the street, each time resulting in a slight, but temporary improvement. The Roto-Rooter guys have told me that there were no significant blockages but that there might be a slight kink in the line under my front yard, resulting in a section of the line actually pitching upward. This would be extremely expensive to fix so I'd like to avoid it if possible. Would an upflow toilet help? Any advice you can provide would be greatly appreciated.

[Norman D]

Let me correct an inaccuracy in my message. The washing machine is about 4 feet away from the toilet but its drain pipe goes into the ground right behind the toilet, so the wastewater from both probably meet only a short distance from the toilet.

[Ned Flanders]

did they run a 2 inch vent up to the attic for the new toilet ? slow flush could be lack of proper vent..

[Norman D]

I saw the hole in the floor and I just put on a wax ring and set it down and connected the water supply. I thought that the existing venting would take care of it since the new toilet dumps into the same waste pipe as the upstairs toilet. Maybe I should just have a plumber look over the whole setup, which is completely out in the open on the other side of the wall, which is the furnace room. Several Roto-Rooter guys looked at it and didn't say that anything was wrong. Not meaning to be too cynical, but maybe the Roto-Rooter guys just wanted to be able to keep coming back!

I've timed the upstairs and downstairs toilets, and even when there's no conflict with the washing machine, the downstairs toilet consistently takes

4 seconds longer to empty the bowl than the upstairs toilet. (They both have 1.6 gallon flushes.) Does that pretty much prove the theory about the vent?

[Mark M.]

Sounds like you installed your toilet over a floor drain which means the toilet is now double trapped. This will never work right. The toilet needs 3" minimum drain line that is vented but not trapped.

Mark M.

I thought that the existing venting would take

[Norman D]