Rough-in plumbing pipes cost on average $4.50 per square foot for new construction, whereas repiping an existing home with PEX tubing typically will cost $0.40 to $2.00 per linear foot. The average cost of installing new plumbing in a home ranges from $2,280 to $5,120. A bathtub, sink or toilet can cost anywhere from $450 to $1,800 to replace.