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This is an idea I had for a story I'm writing. It takes place in a building that has no power, but I'd like for some of its features to still work. One idea I had is a way to keep the water on without the need for electricity.

Just so we know, I'm not an engineer or mechanic, so I don't know much about this stuff.

My idea was for the structure to be placed next to a creek or river. This flow would turn a waterwheel which in turn would turn an archemedes screw to carry the water to the top of the building (maybe to a storage tank). Of course, using water directly from a natural water source isn't such a wise idea due to contaminants that could enter the water from upstream. This is why the water would be carried to the roof, because from there it could drain down through a filter (basically just a container of sand, which I've heard can be quite effective at removing bacteria and whatnot, and was actually used in the ancient world). After that, it would flow into a lower reservoir from which it would go throughout the rest of the building.

I don't know if this would work in reality. Can a waterwheel actually power an archemedes screw that draws from the same water that powers the wheel? Would height matter, given that as the screw took up water it would be adding weight to itself which the wheel would have to fight against. How strong of a current would you even need for this to work? I've seen waterwheels in real life that were powered by creeks, though I'm not sure what they were used for. Even so, this would leave a problem where all the water throughout the facility is gravity fed. And yes, the water would have a way to flow out. All waste products would be dumped into the creek/river downstream from the screw.

Would any of this work in principle? I can't find much about what these things are used for. In the past they were primarily used for irrigation. Today they're often used in circumstances where the water has physical objects in it that would interfere with other types of pumps (waste disposal and fish ponds being two examples I have found). I also recall reading that they were used in the Hanging Gardens of Babylon to draw water up to the upper levels. Of course, I've never heard of anyone actually using the water. When you do read about water systems in the ancient world, normally they were simply 'powered' by digging a tunnel to the bottom of a lake that was at a high elevation. The ancient Romans used this for their fountains, and many of them are still working to this very day! They did drink from these (which was actually their primary purpose oddly). I do know some ancient people had things like baths and showers, but I've never heard of how these things worked. Point is, it doesn't appear that an archemedes screw is something you should use if you want high throughput. It may work if the water isn't being used all the time, so it can be stored up to create pressure when it is needed.

Either way, its an amusing little project. Could such a thing work in reality? Has anyone ever tried to build something like this? Practical of not, its an interesting idea to consider. A completely analogue water delivery system that needs no outside power of any sort.

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  • $\begingroup$ water purification and distribution is irrelevant to the question about the archimedes screw ... it just adds clutter to the post $\endgroup$
    – jsotola
    Mar 1 at 6:35
  • $\begingroup$ What is wrong with the answers given? Why don't you accept one or even vote for them? $\endgroup$
    – Solar Mike
    May 1 at 5:32
  • $\begingroup$ You should have asked this question in worldbuilding.se $\endgroup$
    – joojaa
    May 1 at 9:14

3 Answers 3

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An Archimedes screw requires rotational power to turn it. A water wheel provides rotational power. In principle it should be possible to make it work. There are a few practicalities:

  • Waterwheels and turbines work best when there is a height difference between the inflow and outflow. Just lowering a paddlewheel into a river won't generate much power. As soon as you apply a load to the shaft the wheel will slow down or stop and just obstruct the stream. Most mills used a millrace to generate a fast flowing stream of water which hit the paddles or buckets so that -gravity would extract much of the potential energy before release and the impact of the water would contribute from its kinetic energy.
  • The Archimedes screw runs at an angle. It won't work in a steep or vertical orientation.
  • There will be some clearance between the screw and the channel. This will create a leakage path back to the source. Losses will be proportional to the length of the screw. Losses can be reduced by tighter tolerances but that means shorter screw length between support bearings. That in turn means a multi-stage system but that could be an advantage as now you can zig-zag the screws up the side of the building. I imagine the Babylonians rose the water to height in stages too.
  • With leakage, etc., you might find that a multi-stage system with decreasing screw size is the most cost effective. A wild guess, but let's say you could get 80% of the water drawn in out of the top you can see that the second screw only needs 80% capacity of the first and the next one needs 0.8 × 0.8 = 64%, etc.
  • Power required will be proportional to the sum of the water pumped in each stage × the height of that stage + friction losses.
  • The driving wheel, obviously, has to be able to capture that much power.

You could also have a look at "hydraulic ram pumps" which operate without external energy (other than that provided by the fluid).

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  • $\begingroup$ So, this gonzo idea of mine may not be the best way to provide a building with water when there's no power? Maybe also it would be 'simpler' to just have some on-site source of power? I know this old mill in my town was powered by some tiny hydro dam built in a local creek. I have no idea why such a tiny thing should be able to power a complex that would dwarf a football field and has at least 4 floors, but clearly it did work. Solar panels are another option I guess, since unlike anything turbine-based they don't need their lubricant replaced. $\endgroup$
    – user47074
    Mar 1 at 1:11
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The house I grew up in in England had a water tank in the attic which was filled by city water supply, level controlled with a ball valve. The house was fed by gravity from this tank, the bath was on the second floor just about 10ft below the tank and water supply was excellent -so no problem with gravity feed for you.

Archimedes type screws are also being used to provide power. As for power, there is a flour mill close to where I live that can still operate with a three foot head of water and a screw turbine that was installed about 100 years ago. If you could see all that it powers, it’s quite amazing; it grinds corn meal, any grade of flour and operate other functions. Haines Mill and here Some historic water powered mills

There are waterwheels that run on flow, rather than head, if you have a sufficiently fast stream of water, which are still being installed as micro power plants for off grid applications. As Transistor mentioned, most waterwheels run from a millrace which draws water from further upstream down a small channel, this to maintain a higher head of water.
Archimedes screw design link (Rather complicated!!) Here is a simplified model analysis Archimedes screw

I’m wondering, if instead of an extremely long Archimedes screw, could you have a shorter one connected simply to a pipe that would provide enough pressure to pump water 20 ft or 30 ft high? Here’s a mini example: link

Edit: The AST works equally well as a power generator or a pump. As a power generator it can work off pressure difference (head) or KE (flow). Usually when used as a pump it is flow that is most important, (irrigation, sewage treatment) but there is no reason it cannot be used to generate pressure as its function is completely reversible.

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The usual solution to this in the 1800s was a hydraulic ram. This consists of a long pipe parallel to the stream with a valve in it. When the water runs quickly it sucks the valve open, diverting the flow to a pipe up the hill via a non return valve. The water then slows and the valve closes.

These are reliable and easier to package than a series of archimedes screws. They also don't need gears.

https://en.wikipedia.org/wiki/Hydraulic_ram

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