The average life span of the water line feed from the city main to inside your home is 50-60 years, some may last a lot longer and some may leak earlier due to shoddy plumbing, experiencing electrolysis etc. A repair is not always advised let alone legal to perform, the most important factors to consider are the age of the existing pipe, if there was a previous repair made and the existing material type of the water line.
What material is your water line made of?
Making a repair on a lead or galvanized pipe is not only bad plumbing practice but it is also illegal to perform in NYC. The NYC DEP has updated the plumbing code stating any repair work performed on lead or galvanized piping is illegal and falls outside of the updated NYC plumbing code. If the existing material of your water line is made of copper, ductile iron or brass, you should refer to the age of the pipe to assist in making the most cost effective decision for your needs.
How old is the existing water main?
If the water line is at the point of its average life span it is not advised to make a repair on the pipe. At 50-60 years it is most likely that the water main has surpassed its prime, is more prone to leaking if altered and will require additional repair work in the future.
If you water line is 25-35 years old you should weigh the pros and cons of replacing the main vs. repairing. In many cases it will end up being a few hundred dollars additional to replace the main than to repair it. EX: if your house is on the same side of the street as the city water main, most of the cost is associated with the permits, labor and roadway restoration which would be used for both a repair and replacement. If you plan on staying in your house for many years to come than it may make most sense to replace the entire water line and avoid spending any additional money on future work.
If your water line is 15-20 years old you should factor the cost of water line installations going up over the next 10-15 years along with when your roadway has most recently been paved. When a roadway has been paved within the previous five years, there are additional permit and restoration costs included in repairing and replacing a water main. You can contact the Department of Environmental Protection on future plans for your street and weigh the cost benefit of replacing the line now vs. after the roadway has been paved.
How is the water pressure in the house?
If you are experiencing problems with the amount of water pressure in your home, you should have a licensed master plumber analyze the size of your water line with the amounts of plumbing fixtures in your home. If you have a leak on your water line coupled with a pre-existing pressure problem, this is a good chance for you to resolve both issues at one time. The Licensed plumber will increase the size of your entire water line instead of making a repair, leaving you with low amounts of pressure feeding your home. Read more about water pressure problems and your home here.
What size is the existing water line in your house?
If you are planning on adding any bathrooms, kitchens, showers etc.. in your home, you should inquire about the current water line size vs. what will be required to properly feed the property when you have the additional plumbing fixtures installed. You want to avoid spending money on repairing a water line leak today when you know there may be a need for additional work in the near future.
It is also common that the previous owners may have added showers, sinks, toilets etc. in-between the time when the original water line was installed and you moving into the house. You may have an undersized water line feeding the house due to previous upgrades; in this case it also makes more sense to increase the size of the water line to make sure the property has sufficient water pressure for years to come. You also want to keep up with city requirements to avoid being mandated to increase the size of the water main feeding your home.
Read more about what size water main your house may requrie here