How to Move Plumbing Under a Concrete Slab

Call your city or county Department of Housing and/or Building, the Plumbing Division, to find out if you need a permit for your plumbing work. In many cases, a permit will not be required if you're moving existing fixtures -- but if you're adding new plumbing, one will likely be required.

Apply for the permit, if necessary, and pay the required fees. Do not begin any work until you've received your permit.

Locate the blueprints to your home by getting them from the original builder or contractor. Your county clerk's office may also have these plans on file, but you'll have to pay a fee to receive them if so. The blueprints will show you where the plumbing lines run under the slab; if you cannot obtain them, draw up your own plans and find the piping with an electronic pipe locator.

Remove the flooring in the room where you're working. Carpeting and linoleum should be cut with a sharp knife, pulled up by hand and discarded. Tiles must be busted up with a sledgehammer and disposed. Wood flooring must be pried up with a crowbar.

Break up the concrete only where you must, using a small jackhammer. Remove concrete only where you need access to existing plumbing and where you plan to place the new plumbing.

Haul the pieces of concrete away in a bucket or wheelbarrow and dispose.

Turn the shut-off valve for the toilet, sink or tub you're working on and test the water. If the fixture you're working on does not have its own shut-off valve, you must go outside your home and locate the main shut-off near the street.

Cut the existing pipe just beneath the trap -- a curved, often P-shaped length of pipe found beneath fixture drains -- with a small handsaw.

Attach a new fitting to the cut piece of pipe. Use a soldering iron -- on metal pipes -- or plumber's putty to seal the connection and prevent leaks.

Attach your new piping to the fitting. A new fitting must be placed for every bend and turn in the pipe. Seal the connection between each joint.

Run the new piping to the existing drain line you located beneath the slab.

Turn the water back on at the shut-off, and test the lines for leaks. Fix any leaks that appear by readjusting fittings, re-soldering or adding plumber's putty, and test again. Proceed when the new plumbing is sound.

Mix concrete and water together in a bucket to get a thick, even consistency.

Pour concrete over the broken-up areas of slab while the mixture is still wet.

Level the concrete out with a trowel to even it and remove imperfections.

Leave the concrete to set and cure for approximately seven days.

Replace the flooring by laying new linoleum or carpet, installing new wood or tile.