How much to replace a well water holding tank?

You need to give MORE specific information. There are a number of types of tanks. The primary holding tank in a normal domestic well system is a 'bladder pressure tank.' These usually have a grey pressure switch at the input pipe. - They can be piped in with different methods. However, I have replaced 3 this week in 3 hours, 3.5 hours and 5 hours. The longest one had copper piping and took a lot of disconnecting and reconnecting in sequence. Most (as in the 3 hour one ) have flexible high pressure pipe and are easier to work with. Some tanks are not pressure tanks, but purely 'Holding' tanks usually used in connection with a low producing well. Thes have a pump used to supply the pressure tank. YOU must define whether you are referring to a pressure tank, or just a holding tank. The actual pressure tanks range in cost according to size. A 33 gallon tank is normal in a house and cost around $350 for the tank. They go up to a 120 gallon tank for large houses, which are around $850 each.