Dealing with a rotted-out cast iron kitchen drain can be a daunting task, but replacing it with ABS (Acrylonitrile Butadiene Styrene) can bring a breath of fresh air to your plumbing system. In this blog, we will provide a step-by-step guide on how to replace a rotted-out 2″ cast iron with ABS for a kitchen drain. With the right tools, materials, and know-how, you can ensure a smooth and efficient replacement process that will improve the efficiency and longevity of your kitchen plumbing.

1. Gather the Tools and Materials

Before starting the replacement process, gather all the necessary tools and materials. You’ll need a reciprocating saw, ABS pipe cutter, screwdriver, plumber’s wrench, ABS cement, ABS fittings, and safety equipment.

2. Shut Off the Water and Disassemble the Drain

Turn off the water supply to the kitchen sink and remove any accessories connected to the drain, such as the P-trap. Use a screwdriver to detach the cast iron drain from the kitchen sink.

3. Cut Out the Rotted Cast Iron

Carefully use a reciprocating saw to cut out the rotted cast iron section. Take caution to avoid damaging other parts of the plumbing system. Dispose of the old cast iron safely and responsibly.

4. Measure and Cut the ABS Pipe

Measure the length of the cut-out section and cut a corresponding piece of ABS pipe using an ABS pipe cutter. Ensure a precise and clean cut to facilitate a tight fit.

5. Dry Fit the ABS Pipe and Fittings

Before permanently attaching the ABS pipe, dry fit it along with the ABS fittings to the existing plumbing system. Make any necessary adjustments to achieve a proper fit.

6. Apply ABS Cement and Assemble

With the dry fitting completed, disassemble the ABS pipe and fittings. Apply ABS cement to the ends of the pipe and fittings and quickly assemble them back in place. Hold the parts together for a few seconds to ensure a strong bond.

7. Reattach the P-Trap and Test the System

Reattach the P-trap and any other accessories you removed earlier. Turn on the water supply and test the system for any leaks or issues. Make any adjustments if necessary.


Replacing a rotted-out 2″ cast iron with ABS for a kitchen drain is a practical and essential task to maintain the functionality of your plumbing system. Following this step-by-step guide, you can confidently complete the replacement process and enjoy the benefits of a durable and efficient ABS kitchen drain.