One of the most unpleasant things that can happen to your toilet is leaking corrugation - it can bring lots of troubles.
Leakage can cause mold, floor damage, and lots of other things that can damage your house, so it's better to fix it quickly.
Here's how you can do that.
First, locate the water valve behind the toilet, usually near the floor. Turn it clockwise to shut off the water supply to the toilet.
Flush the toilet to remove any water left in the tank and bowl. This will make the next steps less messy.
Unscrew the nut connecting the corrugated water supply line to the toilet tank. You might need pliers or a wrench to do this.
Be prepared for a little water to drip out when you disconnect it.
Check the corrugation for any cracks, splits, or damage. If you find any, it's best to replace it with a new one.
You can find a replacement at your local hardware store.
If you're replacing the old one, attach the new corrugation in the same way you removed the old one.
Hand-tighten the nut, and then give it a little extra turn with pliers to ensure it's secure, but be gentle to avoid over-tightening.
Turn the water valve counterclockwise to reopen the water supply to the toilet.
Once the water is back on, watch for any leaks around the new corrugation. If you see any, tighten the nut a bit more.
Flush the toilet and make sure it fills properly without any leaks.