Installing a new water line under a slab foundation may be necessary during house renovations or when you are adding an extension to your house. Running a new water line under a slab foundation is a major task and you should only carry it out with the help of a friend. You do not need to be an expert to run a water line under a slab foundation, but you do need to take precautions to avoid causing any damage to your house.
Determine the location where you want to place the new water line. Clear the work area of obstructions.
Break up the floor using a hammer where you want to place the new water line. Dig a hole until you reach the slab foundation. If your garden is on the other side of the wall and foundation, dig up the soil in a 3-foot-by-3-foot area using a shovel until you reach the slab foundation. Make sure you do not dig under the foundation or cause any damage to the wall.
Cut a hole through the soil under the slab foundation using a high-pressure washer. Place the hose end to the soil under the slab foundation and turn the washer on. The high-pressure water will cut a hole through the soil through which you can lead the new line under the foundation. Work quickly so you do not remove too much soil. Wear protective goggles.
Push the PVC or metal pipe under the slab foundation through the hole you have cut using the high-pressure washer. Connect the water line to the main water pipe.
Replace the soil you have removed during digging. Make concrete using concrete mixture to repair the floor you have broken up. Follow the manufacturer's instructions for mixing the concrete.
Ask a friend to help you run the new water line under the slab foundation. He can stay on the other side of the foundation and assist you by giving directions which way to direct the washer or which way to lead the PVC pipe.