There is no definitive answer to this question as it depends on a number of factors, such as the condition of the pipes, the climate, the water quality, and the amount of use. However, most experts agree that water mains should be replaced every 30–50 years. If you’re thinking about replacing your water main , we recommend contacting a professional to get an accurate estimate of the cost and time involved. Replacing a water main is a complex and expensive project, so it’s important to make sure that it’s absolutely necessary before proceeding.