A new 40-gallon gas water heater with a six-year warranty costs about $600. If you do it yourself, plan on four hours or so for the job.

Your water heater should have instructions on its side explaining how to do this. Be careful, though: If you smell gas from your heater, leave your house and call your gas company for assistance.

Does your water need repair to keep it running smoothly? This comprehensive guide will help you maintain your water heater so it lasts for years to come.