The water main valve (AKA house control valve) is used to stop the flow of water from the city water main to inside the house. The water main valve is usually located within 2’ of the foundation wall and is most commonly used when an internal plumber has to repair piping on the inside of the house. The type and size of a water main valve in a building may vary pending type of water main (domestic or sprinkler), size of the pipe, and the year it was installed.
If you have experienced a broken or leaking water main valve you must first stop the water flow from the city main to inside the building, there are several options as to how the water can be turned off. A curb valve is usually located within 2’ of the city curb line and can be used to stop water from flowing to the inside of the building. A curb valve can be closed using a curb key however; it does take experience and a level of expertise, especially when the curb valve is giving resistance. Another option would be to close the water at the tap connection which is usually located 4’ below ground level in the roadway.
The option of closing the tap connection in the roadway becomes costly due to the required DOT permits, labor and material for restoring the roadway. There are many scenarios where this is the only option due to a broken curb valve or if the water line is too big or old to work with under pressure. The final option is working “on the fly” or under pressure is the most cost effective option yet is extremely risky and can become quite expensive if not handled properly. Working under pressure means the water continues to flow from the city main to inside the building and if not managed properly it can result in a great deal of damage to your basement and the surrounding electric services.
The most common reasons for replacing the water line valve are if there is any work being performed on the internal plumbing, if the existing valve is not closing or is stuck in a halfway closed position, or if a new meter or backflow prevention device is being required for the building. If you are experiencing any of these issues it is very important that you consult with a licensed and insured master plumber to work on the repair.