We finished our basement last year and installed a bath also. There are toilets that are made with a pump/grinder in a base below it but I believe it required a step up to the toilet. We installed a crock in the floor in a utility room behind the bath with a pump to the sewage line. You will need to vent this as well. This was the cleanest look for us and what we thought was the proper way to do it. The cost for us was about 800 in labor plus material to install the crock and piping.

Just a toilet? I would think any future homeowner you'd want to sell to would demand a sink to wash hands after using the toilet. I would imagine you could use the drain and water lines.

In most localities the health codes require that any room equiped with a watercloset MUST HAVE a sink for washing your hands.

If the floor of your basement is lower than the gravity flow house drains you will need a sewage ejection pump to lift the discharge up to the drain line.

There are small self-contained sewage ejectors that will sit on the floor and can be equiped with a conventional toilet as well as permitting the discharge from a sink however the plumbing codes are very restrictive in how to install a sewage ejection pump system.

1. The International Residential Code requires that we compute the load at 1.5DFU's for each 1GPM from the pump. Minimum pump size is 14.2gpm so the minimum DFU load is 1.5DFU x 14.2gpm = 21.3DFU's for the pump. This value must then be added to the existing fixture load on the drain line to determine the required size of drain line.

Under the IRC a 3" horizontal branch line is limited to a maximum of 20DFU's therefore even though the discharge line from your pump may be a 1-1/2" or 2" line it may not be connected to a branch line. It must be connected to the house main drain line providing the combined load of the pump and existing load do not exceed the maximum rating of the main drain. (A 3" horizontal main drain with a 1/4" per foot pitch is limited to 42DFU's.

The sewage ejector must also be equiped with a dedicated vent through the roof which may not be combined with any other vents in the structure.

There are also a number of requirements on how the discharge line must be connected to the drain line.

While the Uniform Plumbing Code assigns different DFU values to both the fixtures and the piping the end result is the same, the discharge line MUST BE connected to the house main drain line, not a branch unless that branch is at least a 4" line.