How to Install a Toilet in a Basement With a Rough-in Pipe

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Installing a toilet onto an existing rough-in pipe isn't difficult. The dividends in convenience are well worth the trouble and minimal expense if both water and sewer are roughed in.

Toilet rough-in with supply line

Things You'll Need

  • Flexible Toilet Supply Hose

  • Hacksaw

  • Wax Toilet Bowl Gasket With Rubber Gasket Flange

  • Open-End Wrenches

  • Hammer

  • Toilet

Step 1

Install the water supply line on the left side of the toilet nine to 12 inches from the floor. Fit the supply line with a 90-degree shutoff valve.


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Step 2

Close up of toilet flange. Insert the closet bolts at the red marks and move them to the blue marks. Remove the center plastic disk with a hammer.

Remove the plastic knock-out cover from the floor flange by tapping it with a hammer to break it away. Place the wax seal onto the floor flange with the rubber side in the drain.

Step 3

Insert the closet bolts that came with the wax seal into the toilet flange slots on the floor. Move them until a line drawn between them is centered over the drain and parallel to the wall.

Step 4

Lift the stool over the flange, align the mounting holes with the closet bolts and set the toilet down. The closet bolts should now protrude from the mounting holes on the toilet.


Step 5

Press the toilet stool down fully onto the flange until it contacts the floor on all sides of the stool. An easy way to do this is to temporarily place the seat on the stool and sit on it.

Step 6

Put a supplied washer over each bolt and follow with a nut. Turn the nuts down until finger tight. Use an open-end wrench to tighten firmly, but do not over tighten as porcelain cracks easily. The goal is to tighten enough to keep the stool from rocking. If too much of the bolts protrude after tightening, cut them off with a hack saw.


Step 7

Complete assembly of the toilet according to the manufacturer's instructions. When tightening the bolts that connect the tank to the stool, use the same caution to avoid over tightening and cracking the toilet. It is better to tighten a little more later than crack the toilet now.


Toilets are heavy, bulky objects and breakable, so you might want elicit help getting it in place. A helper can also align the closet bolts for you. Snap-off closet bolts can be purchased for under $5. If your toilet came without snap-off bolts, consider these to make the job easier. Use pliers to break them off where you need to.


Porcelain can crack easily resulting in an expensive mistake. Use small open-end wrenches and not sockets. Small open-end wrenches will help you control the torque applied to the bolts to keep you from cracking the porcelain.


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