Waterblock/Flow Meter

I have been water-cooling computers for over eighteen months. During this time, I have constructed seven different water blocks.

Recently I posted some pictures of my computer and its latest water block at HardOCP and Virtual Hideout.

These pictures and the recent article on the Bucket Bong have prompted many inquiries about the design of my water block. Today, I will show you how to build your own.

About a year ago, Overclockers.com showed one of my 2nd generation waterblocks:


This block is an aluminum junction box for electrical cable. It was a good performing, low cost solution, but two metals created a great deal of galvanic corrosion inside the block.

This experience and some inspiration from SurlyJoe led me to refine my requirements for any future work, which are as follows:

  1. The block must be made from only copper, to limit corrosion
  2. The parts must be inexpensive and easy to get.
  3. The block should include a window so that I can monitor corrosion or algae growth.
  4. It must look good.
  5. The process must require a minimum of tools. I live in an apartment. Like many of you, I do not have access to a machine shop.

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Below is the result of these design requirements: A high turbulence waterblock/flow meter.



I constructed the block from a 2-inch plumbing cap combined with a few other plumbing parts. I then used Marine Goop to attach the clear plastic plate. It’s quite comforting to look at the spinning rotor and know that I have adequate water flow.

The cooling is quite good because the copper parts create lots of surface area and the coldest water flows straight down the center shaft to cool the chip, before it exits, spinning the rotor. When combined with the Bucket Bong, the performance is very good, but probably not quite as good as the Danger Den maze blocks.

This water block cools a Duron 600@1070, 2.10 volts and also cools an overclocked Voodoo 5 5500. The processor runs at 26c/78f at 80% load and does not rise above 30 C under full load.



Next, I’ll tell you how to build all this.

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How To Build This

This water block is easy to make. You need very few tools. A drill and hacksaw will be adequate. If you are careful, the cost of this project, with the exception of the pump should be under $20.

You will need:

  1. One 2 inch copper pipe cap
  2. Three half inch to 3/8 copper hose connectors
  3. One piece of Plexiglas, 3.5 x 2.5 inches
  4. One plastic washer from a CD spindle
  5. One McDonald’s straw
  6. A small amount of solder


The first step is to lap the copper cap to a reasonable degree of smoothness. I like to do the heavy sanding before I attach any more delicate parts.

It is important that you smooth both the bottom and the top. These caps can be quite rough and a smooth finish will ensure a good seal to the Plexiglas plate.

You can also see that I like to use many progressively finer grades of sandpaper. This makes the work go faster. I do all my sanding on a thick piece of plate glass to ensure flatness.


The next step requires that we cut one of the copper hose connectors at an angle and solder it inside a matching angled hole near the top of the copper cap.


We then cut a T-shape in one of the other copper hose connectors. Pliers are used to bend one flap inward and the other outward. This forms a directed nozzle that will cause the water to swirl inside the block.


In earlier designs I used a tiny elbow to direct the water flow, but I think this is simpler

The next step is optional. A wonderful way to make copper heatsinks is to use copper rivets. They cost between 5 to 25 cents, depending on the size.


I put rows of them on video card RAM, clock generators, or anything else that seems to need it. They make copper ram sinks that cost $5 apiece seem silly.

Just make sure that you lap the bottom each one before using. On this water block we will add a few over the CPU core to help draw out the heat.

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I don’t have many tools, so I just solder things by heating them on the stove.


The wet piece of paper towel keeps the previous joint cool while the bottom gets hot enough to melt the solder and bond the parts. Notice how the angle of the inlet and outlet cause the water swirl in a clockwise motion.

A moment after I shot this picture, I moved a rivet and turned the centerpiece clockwise about a quarter turn to ensure that the water would swirl and not go directly out the hose connector near the top.

The end result should be something like this:


Use as little solder as possible, as the solder has a much lower thermal conductivity than the copper Just place a bead around the outside of the center piece.

You can see by the mark of the removed heat sink that the heated solder spreads very easily under the parts. When done right it is like a thin film between the parts.

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The final stages involve constructing the rotor and assembling the finished unit.

The rotor is made from a washer from a CD spindle and a McDonald’s straw. Cuts are made into the washer with a razor. The rotor blades are made by cutting the straw in half and pushing equal lengths into the cuts on the washer.



A drop of superglue at each joint then bonds all the blades.

The last hose connector is cut into two to create a small copper riser that is gooped to the center shaft. This keeps the rotor spinning well above the rivets. I also add a drop of goop to the flap so that the water flow stays focused as it exits the center shaft.

You are now ready to add the rotor and the remaining piece of the copper hose connector. If you have done everything properly this should be the result.



Make sure that the rotor blades are facing the right direction.

We then add the Plexiglas, which has been drilled to match the hose connector and the holes in your motherboard, and do a few tests before gooping everything together.

Before bonding, I like to take the unit and place it inside the case over the processor to verify the best positioning of the hoses.

It is also good to attach the pump and run some water though it while holding the Plexiglas tightly in place. It will leak, so stand over the sink, but it should show whether your rotor is spinning freely.

You may have a sharp edge or stray drop of glue jamming the rotor. If so, you need to find this out and fix it before gooping.

Gooping is the point of no return. Be very careful at this stage of construction. If everything is perfect, then goop the hose connector to the center shaft and test the rotor to see that it still spins.

If it does, bond the Plexiglas to the block with beads of goop on both the copper cap and the outside of the hose connector.

Let it dry a day and test it with water flow for another day before installing in your computer.

I have now made my third block of this type. I have been very careful and I have not had any leaks.

Please feel free to make your own version of my design by adding your own improvements. I would enjoy seeing your results posted on the website.

The constant exchange of ideas in the overclocking community keeps it all interesting.

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