Combined Water Main Installation Cost & Process
February 1, 2017

As time passes it seems that the DOB (Department of Buildings) is becoming more restrictive with their requirements to protect a property using fire sprinkler protection. What most people don’t know is that this will require installing a new water main from the roadway, to inside the house and at this point having sprinkler heads installed in the house.

Most people’s initial comments include “I already have a water main, why can’t I use this to feed the sprinklers?” In most cases the pre-existing water main size is not large enough to supply the required volume and pressure which is determined by the engineer who is working on approving your plans.

The second most common variable has to do with the existing valves, and what is required for any water service supplying a building with fire protection. Many domestic water mains are installed using a ball valve which does not comply with the plumbing code when installing a combined or sprinkler water main. It is always required to have an OS&Y valve installed, the stem on this type of valve serves as an instant notification  as to whether the valve is open or closed.

Ball valve for domestic water main
Ball valve for domestic water main

OS&Y valve for Sprinkler
OS&Y valve for Sprinkler

This type of water main also requires a curb valve which is not required on all domestic water mains. The curb valve would be utilized if the Fire Dept. had to turn off the water from the outside of the building and could not gain access inside the building.

Curb valve below ground
Curb valve below ground

Curb box/Access point
Curb box/Access point

Combined vs. Sprinkler water main

For the most part these two water lines are exactly the same. The only difference is that the combined water main feeds the domestic water as well as the sprinklers. Once the combined water main enters the house it branches off and feeds the building as needed.

A sprinkler main is designated to feed the sprinkler heads throughout the building. In this case the building would have another water main designated for the domestic water system.

How much does a sprinkler main cost?

The overall cost of a combined water main or sprinkler main varies pending the location, size of the pipe, linear footage, depth of installation etc. You may have a new 2” combined water main installed on a small side street in Brooklyn totaling 25’ of new pipe for a total cost of $12,000.  On the very next day we may install a new 3” water main two blocks away on a major thoroughfare, totaling 60’ of new pipe and may cost $35,000.

Installing new sprinkler across Beach channel
Installing new sprinkler across Beach channel

Installing on West 4th st NYC
Installing on West 4th st NYC

It is always important to have an onsite estimate performed to get an exact price, including a detailed proposal including all of the pricing variables.

The installation process

The installation process includes excavating over the city main, in some cases may require trenching 75% of the job from the street to the foundation wall pending the layout.

Mid install
Mid install
Progress
Progress

Once the excavations are completed the new pipe is installed in the trench or through the tunnels.

Pipe is in!
Pipe is in!

All water mains serving as fire protection will require an on-site inspection by the DEP before the street/sidewalk is back-filled, and once processed by DEP, a formal sign off is issued to the licensed plumber. In most cases the property owner needs this sign off to obtain his certificate of occupancy.