Laminar Water Jet Design
The following webpage describes the steps I used to build a small water feature in the entryway to my house. It's called a "Laminar" water jet. While it's by no means the caliber of laminar jet you'll see at the casinos in Vegas, it was relatively cheap and easy and I think brings some excitement to an otherwise boring entryway.
Designing the Laminar Jet
It doesn't take much searching around to the web to find a ton of different designs for building your own laminar water jet. In the general, the larger the diameter of your cannon the larger stream, larger flow, and longer distance you can make your jet shoot and still have a nice laminar flow. Some designs claim to build a laminar jet for $15 others for $300. I picked the middle of the road. I wanted something robust and something that wouldn't leak all over the place.
Laminar Jet - Materials List
I took a trip to Lowe's and spent about $50 on materials for my laminar jet design. I picked up a 24" piece of 4" ABS pipe that I cut down to 16". I also picked up some fittings to reduce the 4" pipe to a garden hose fitting. Also on the list were some test plugs, shown in white, various size washers to test, and an end cap that could be unscrewed for cleaning out the water jet down the road. I used some 2" thick filter media, scouring pads work fine as well. You'll need about 200 drinking straws as well.
The first step was to cut a few circles out of the filter media or scouring pad, just larger than the diameter of the pipe. I stuffed the 4" to 2" reducer fitting full and then fit on the 4" ABS pipe.
The next step is to fill the pipe with drinking straws. You want to fill the pipe and full as possible with the straws. The straws I used had the flexible tops and they worked fine.
After the straws are in place, you press in the second round of filter media. If the diameter is a little larger than the pipe, it will take some effort to get the material in the pipe which is good. It will hold all your straws firmly in place. There should now be just a couple inches of free space from the top of the filter to the top of your pipe.
Testing your Water Jet
To see what size jet would work best I used the test plugs and drilled various size holes and ran a few tests with a garden hose.
I found I liked a 1/2" hole best and could create a nice stream 8-9 feet in distance before the stream was no longer laminar.
Next I installed the permanent fittings on the water jet. I used the 4" ABS screw plug and drilled a 7/8" hole in the top. I then glued in a metal washer that had a 1/2" diameter center hole. You have make sure there are no metal burrs or glue on the edge of the jet hole. A little emery cloth works well to clean up the inside of the washer. 100% silicone worked best for holding the washer in place.
The finished laminar water jet design is shown above. Once I had all the materials in hand, it took me about 1 hour to assemble and have a jet ready to go. Some folks like to tinker around for days trying to perfect the jet. I found something that worked relatively well and just went with it.
Landscaping with Laminar Water Jet
Installing the water jet into the landscaping is where you have a ton of options. Most people will rig up a pump and recirculate the water. I took a different approach and tied an old shop vac tub to a pipe and then tied it into the storm drain. The laminar jet is fed by secondary water. I ended up putting a 25psi pressure regulator and a valve to get the exact and constant pressure I needed. The secondary water is controlled by a sprinkler valve and tied into my sprinkler controller. I can have the water come on a a few hours a day or whenever I like. In the future I may tie it into a motion detector so that I only comes on when somebody walks up towards by front door.
I had some old bricks laying around and some gravel and made a couple of circles. One catches the water for the drain and that other surrounds an oversize sprinkler valve box that contains the laminar water cannon. I can pull back the gravel and remove the valve box cover for any maintenance that may need to be done in the future.
Here's the finished product. The laminar water stream drops into the middle of the catch basin perfectly every time it is kicked on. Now I just have to add some bark, a few shrubs, and flowers to make the entryway very inviting!
Here's a short video clip of the final design.