The CSIRO described their work in a media release:
While the general concept of using an aerated showerhead to save water is not new, the technology behind the CSIRO's device is novel.In 2005 I bought an aerating shower head from the Australian business E-Co Shower. As CSIRO describes, the unit sucks in air, and mixes it with the water to give you a shower of bubbles.
Developed by a team led by Dr Jie Wu, the aeration device is a small nozzle that fits inside a standard showerhead. The nozzle uses a small Venturi tube - a tube for which the diameter varies, creating a difference in pressure and fluid speed. Air is sucked into the Venturi tube as a result of the partial vacuum created, causing air and water to mix, forming tiny bubbles within the water stream.
From: 'Air shower' set to cut water use by 30 per cent, Media Release 06/223, CSIRO, 9 November 2006
As pointed out on PhysOrgForum, what CSIRO announced appears to be very similar to the existing E-Co shower. Even some of the wording of the the CSIRO media release appears similar to the wording of the E-Co web site from 2003:
- E-CO : "air and water mixing together causes bubbles"
- CSIRO: "air and water to mix, forming tiny bubbles"
Previously I tried a water saving shower head. When on the high setting this produced a narrow jet of water. I had to move around it the shower to get my whole body wet and the force of the water was almost painful. On low setting it produced a fine mist which did not seem to wet the body. Either way it was not a pleasant result.
The E-Co units seem to be particularly popular with institutions. There is a vandal resistant model which just has a small hole for the water to come out of, instead of the usual rose pattern. The unit is only about 20mm wide and 40mm long and can be securely connected to the pipe coming from the wall. As a result there is little for anyone to vandalize.
Also there is the Oxygenics shower head. I am not sure I believe the health claims for the "oxygenated" spray, but it seems to operate on the same principle as the E-Co and CSIRO units and they have a clever animation showing how it works.
The only innovation in the CSIRO approach seems to be that it is an adapter designed to be added to a normal shower head whereas E-Co make a complete shower head. E-Co make an adapter for hand-held showers and basins. E-Co include testimonials from Canberra residents and from the Department of Defence, so it it difficult to believe that CSIRO didn't know of it.
The innovative technology behind Oxygenics® is based on the Venturi Principle. As water enters the base of the showerhead, it is propelled through an accelerator fin to increase the velocity of the water flow. It is then directed through a channel where oxygen is injected into water. The result? Phenomenal coverage and a continuous range of sensations - from a soft relaxing spray to a deep, therapeutic massage to everything in between. Are you ready to be wowed? Get ready for a healthy, powerful, oxygenated spray!
From: Oxygenics, 2007
There is also a US Patent for such a device from 1978, complete with diagram:
The passage of water from conduit 17 and through the chamber within the shower head establishes, in accordance with the Bernoulli, or venturi principle, a low pressure environment within the shower head. The low pressure environment tends to draw ambient air through outlets 20 and 21. The drawn air mixes with the water within the shower head due to the turbulent nature of the flow therein and is ultimately ejected through nozzles 31.There are only two things I have found wrong with the E-Co shower: is the price and the web site used to sell it. The price is very high compared to a cheap plastic water saving shower head. But the device is very well made, from solid metal and comparable in price to fashion shower heads. E-Co let the quality of the product down with a poor web site, which makes it hard to buy.
Because the ejected jets of water are mixture of air and water, the spray striking a bather will not have the conventional sting of sharply defined jets of water. Instead, the spray will tend to be "softer" and produce a physiological massaging effect which is very pleasant. Aside from the physiological benefits, the amount of water seemingly necessary to provide the bather with a shower to which he has become accustomed to, consumes approximately one-half of the normal water useage. Thereby, aerator 15 can effect a water savings of approximately 50 percent and yet require no change in habits by the bather nor in any manner curtail or restrict the habits developed from a lifetime of showers."
From: Shower head aerator, Richard Harmony, United States Patent 4072270, February 7, 1978
There is also another use for a Venturi in a shower: This is the "Venturi shower", where cold mains pressure water is used to draw hot water from a low pressure tank:
"High pressure mains cold water is used to "suck" tank pressure hot water through the special venturi valve inside the unit, so that the resulting mixed water comes out at a much greater rate than could be achieved using an electric shower or ordinary shower mixer valve. The venturi shower uses no electrical connections, it simply plumbs straight into the heating system."
From: Venturi Shower, tubz.co.uk, 2007 http://www.tubz.co.uk/venturi_shower.php