If you run a water utility, a city water system, a hospital or a large facility and need a new connection on an existing main, the first question in any wet tap vs. dry tap decision is simple: can that main come out of service? A wet tap, also called a hot tap, makes the connection while the main stays pressurized and operating. A dry tap is made on a main that is out of service. This guide explains when each one fits and what to send Koppl before a technical review.
Wet tap vs. dry tap: the short answer
- Wet tap (hot tap): the connection is made on a pressurized, operating main. A fitting and valve are installed and tested first. Then a tapping machine cuts through the open valve.
- Dry tap: the connection is made on a main that is not in service. That can be a new line before it goes into service, or an existing main that has been shut down.
Industry guides describe the same split. McWane Ductile's overview of [pipe tapping methods](https://mcwaneductile.com/blog/what-are-the-three-pipe-tapping-methods/) notes that a dry tap can be made on a new line before it is placed in service, while a wet tap connects a new service to a pipe that is already live.
What a shutdown means on an existing main
A dry tap on an existing main means shutting that main down first. An Opflow article summarized by [American Leak Detection](https://americanleakdetection.com/blog/2009/june/whats-the-best-way-to-tap-a-water-main-) notes that shutting a main down can cause water loss, raise the potential for contamination, and lead to lack-of-water or dirty-water complaints.
A shutdown is also a coordination job for the owner. Every customer or building on the isolated section is without water for the work window. Notices, scheduling and the return to service all have to be planned around it.
When a dry tap can make sense
- The main is new and not yet in service, so no one on it needs to stay supplied.
- The main is already out of service for other planned work, and the connection fits inside that window.
- Your own utility standards call for a dry connection in that situation. Local rules decide which method applies.
When a wet tap is the better fit
- The main serves customers or buildings that should keep water during the work.
- A shutdown would affect a much larger section than the connection itself needs.
- You need to add a branch, sensor, drain or sampling point on a line that has to stay in service.
Koppl's [hot tapping service for water mains](https://koppl.com/services/hot-tapping/) is built for this case. The crew plans fittings for steel, ductile iron, cast iron, copper, PVC, concrete cylinder and other qualified pipe. A hot tap is not right for every line. Whether it fits depends on a technical review of the actual pipe, its condition and the operating conditions.
How Koppl makes a wet tap on a live main
Koppl follows four stages on a hot tap. The exact method changes with each application.
- Define the line: confirm material, diameter, wall condition, media, pressure, temperature, access and the required connection.
- Engineer the connection: select the fitting, valve, cutter, pilot drill, machine travel, test plan and field controls.
- Install and test: fit and secure the connection, complete the required tests and verify the isolation path before cutting begins.
- Make the tap: advance the cutter through the open valve, retain the coupon, retract the machine and close the valve under a controlled procedure.
Koppl uses a wired pilot-drill retention method, so the cut piece of pipe wall comes back out with the cutter. Koppl also fabricates its own fittings, including SV-150™ tapping fittings with 4 to 24 inch outlets, shown on the [Koppl products page](https://koppl.com/products/). For a longer walk-through of the method, read [Hot Tapping 101: connecting to a pressurized pipeline](https://koppl.com/knowledge/hot-tapping-101/).
What to send Koppl before choosing a method
You do not need to pick a wet tap or a dry tap before the first call. As the guide to [planning municipal water work by service and outcome](https://koppl.com/blog/water-lines-vs-pipelines/) explains, describing the outcome you need is a better start than naming a method. Send what you know:
- Pipe size, material and wall thickness, if known.
- Operating pressure, temperature and media.
- The connection size you need.
- Location and site access.
- Your desired schedule and whether the main must stay in service.
- Drawings and current photos, when available.
Call Koppl at (323) 888-2211. The Montebello office is open Monday through Friday, 6 AM to 4 PM Pacific. For an urgent condition, call the same number. Crew availability and timing are confirmed for each request.
Frequently asked questions
Can a hot tap be performed without shutting down the line?
That is the purpose of the method. A qualified hot tap creates a new connection with the system still pressurized and operating, subject to technical review of the line and service conditions.
What information should I provide first?
Start with pipe size, material, wall thickness if known, operating pressure and temperature, media, connection size, location, access, and the desired schedule.
What happens to the coupon?
Koppl uses a wired pilot-drill retention method so the cut coupon can be recovered with the cutter when the machine is retracted.