Its the second time already at a different location.

Should I change the entire pipe?

Its a 20+ yo house with pvc pipes.

Whats the cost of changing the entire pipe and how long will it last?

Whats the most durable material used these days?

Whats the downtime to changing the entire house?

Depending on the size, changing all the pipping works typically do not take more than a day.

However, due to the age of the installed products, changing the pipes can reveal existing issues that can lead to complications which in turn, will incur longer downtime and costs. (to buy and replace heaters, taps etc)

Currently, the popular materials used are copper pipes, stainless steel pipes and PVC. (in the order of popularity)

All 3 materials are very durable, the main difference is actually the products used and workmanship of the plumber. Also ensure quality copper, stainless steel or pvc are used, as all 3 materials have their own grades as well.