Water floating with 192-fiber – 25,300 ft in one go
Told by fiber technician Michael Walther | 1 March 2025
Preparation is key
We were contracted to install a fiber optic backbone line between two small towns in central Sweden. A week earlier, we had already reviewed the plans and gone on-site to survey the route. On long-distance installations like this, positioning is everything — especially when the terrain includes elevation changes and several bends in the duct.
The client wondered if we should split the cable onto two reels since the total run was about 5 miles. I said no. I know what my equipment can handle — and avoiding a splice in the middle means real savings and better performance for the customer.
Equipment and setup
We were installing into a 40/32 mm duct (approximately 1.57″ / 1.26″), using a 192-fiber cable with a diameter of about 0.31 inches. Two cabinets along the route were looped together as a precaution, in case we needed to adjust the setup during the installation.
For water supply and pressure control, we used a flushing truck with about 2,100 gallons of water.
The Installation – Fine Control in the Field
We began the installation at low pressure — about 60 psi — and let the water run for around 5 minutes before feeding the cable. Flushing first is key; it keeps the cable from getting ahead of the water, which can easily happen at lower pressures. Our starting speed was roughly 400–425 ft/min.
After about 5,250 ft, the cable started to outrun the water flow. We stopped briefly, then continued — this time at 175 psiand about 210 ft/min. Once the pressure stabilized, we reduced it to 115 psi, which brought the speed back up to around 350 ft/min.
At roughly 10,000 ft, we hit what we call “spaghetti fiber” — the cable begins to coil inside the duct, and the feed speed fluctuates. You can even hear it in the machine. But the Jetting V2 gives great feedback — compact and responsive, yet strong enough to handle large drums. By dropping the speed and increasing the water pressure, we were able to regain full control and stabilize the installation.
The Final Stretch – and a Sudden Stop
At about 20,000 feet, we were holding a steady 210 ft/min at roughly 220 psi — right up until we ran out of water. We disconnected the hose, sent the truck to refill, and waited. Restarting isn’t always easy when that much cable is already inside the duct, but after about 15 minutes, we built the pressure back up and kept going without any issues.
In the end, we installed 25,300 feet in a single run — no splice needed. We wrapped up the job by looping the cabinets, opening the duct ends, and labeling the cable.
And calling the client to let him know he wouldn’t have to pay for an unnecessary straight splice? That was the best part.
Advantages of Water Floating
- Up to 50% longer installation distances compared to air
- Water is a more efficient cable carrier than air
- Acts as a continuous lubricant during installation
Downsides of water floating
- Higher cost due to the flushing truck
- Slightly slower feed rate than air
- If the network owner requires flushing the water out afterward, the cost increases further
My Recommendation from the Field
Use air for runs up to 10,000–13,000 feet. Beyond that, water is the better option. Of course, it always depends on the cable and duct you’re working with — but that’s the rule of thumb I go by.
Equipment Used
- Jetting V2 Fiber Blowing Machine
- Jetting V2 Floating Kit
- Jetting Cleaning Plugs
- Jetting Cable Heads
- Flushing Truck
