I do not think there is an owner who has not wondered how to move or repair the plumbing that is under a concrete slab. At a first glance, it seems an almost impossible thing to do it. The concrete slab creates an impression of strength and solidity. In fact, it is not only an impression. You have to remove the concrete slab before you start repair the pipes and drains from underneath. Removing the concrete slab is pretty challenging, really a hard work.
Steps to Take:
1. Before starting, check with your local authorities for the necessary permits. However, if you only want to move the existing fixtures or you need to do only repairs, no permit is required, but if you want to add new plumbing, you will need a permit. Do not start any work, before receiving the necessary permit.
2. The best would be to have the blueprints of your home, where you may see how the plumbing lines run under the concrete slab. Check with the county clerk’s office. They can have your home blue prints and for a fee, you can obtain them.
3. First, you need to remove the flooring (linoleum, carpet, hardwood or tiles).
4. No need to break the whole concrete slab only above the piping line. Use a jackhammer to break the concrete and then remove the pieces.
5. You have to turn off the valve for the fixture you are working on. If you do not have a specific shut-off valve for the fixture, then you need to turn off the outside main shut-off valve for the whole house.
6. Now, it is the time for plumbing work. Using a handsaw, cut your pipe, just beneath the trap.
7. Add a new fitting to the pipe. Seal the connection with soldering iron (metal pipes) or plumbing putty.
8. Attach the new piece of pipe to the fitting. However, you need a new fitting for every pipe curve.
9. Next step is the new pipe running to the existing drain line, which is also under the concrete slab.
10. Turn on the shut-off valve. Make sure you do not have any leaks. If you have leaks, you have to fix them, adjusting the fitting or sealing the pipe again.
11. Prepare the concrete, mixing the composition with water and pour the concrete in the ditch.
12. Level the concrete and allow time to cure.
13. The last step is the replacing of the flooring.