Can a valve compress air in water flow to reduce one's water bill?

Factual Questions
1

I think my employer is falling for a scam, or at least is being misled.

Our corporate dept. wants us to install a water valve just downstream of our main water meter. The valve maker claims this device (in their words) “uses the latest technology to increase the density of water running through a meter which improves meter accuracy. To increase water density, the [device] compresses the air in the water flow as it is being metered. [The device] has drastically improved the efficiency of upstream water past the meter. An additional benefit is the elimination of turbulence that typically accompanies water passing through meters.”

This ‘technology’ is supposed to save us 10-15% off our water bill. The price for a 3-inch valve is $20k. From pictures, it appears to be a valve body with some sort of a spring loaded ‘valve’ to cause ‘backpressure’. Similar devices go by the names of Watergater or theSmartValve.

I can imagine it saving money by simply restricting water flow, but all the scientific sounding jargon about compressing air and turbulence seems suspect. And the testimonials on their websites are really off-putting.

Do such water valve devices actually save 10-15% on water bill by compressing air and reducing turbulence to improve meter accuracy? Reeks of BS to me. Seems like a orifice plate would do the same thing.

2

I’m going to go out on a limb here and cry “bullshit” without even bothering to investigate it further.

Water is not particularly compressible in domestic settings. To increase the density of water by means of increasing pressure, to a point where would it would make an appreciable different to the metering, seems like a load of hooey to me. It’d certainly take more than a 3 inch valve.

I’ll leave to the more experienced engineers to tell us how and in what way this particular bullshit is manifested.

3

Compressing water to save on metering is flat-out nonsense. Water is, for daily purposes, essentially incompressible*.

Air dissolved in water isn’t floating about in discrete pockets like in a beer or soda (that’s gas that’s broken out of solution), it’s actually individual, discrete atoms of gas, finding spaces in between the incompressible water. You can’t meaningfully compress that either.

If you’ve got actual bits of air in your water, you have a problem that can be solved by bleeding your pipes, and (though I’m no plumber) I expect you’d be hearing the pipes gurgling.

* When I said “essentially incompressible”, you’d need roughly 1,000 atm of pressure to get a 5% compression ratio in water. That’s not what they’re claiming per se, but that’s the only part of their claim that makes sense.

** Quick edit: A look online suggests “the Smart Valve” restricts your water flow. If you’re saving 10% to 15% of your water bill, it’s because you’re using that much less water. I suspect that, past the hooey, that’s what the other valve is doing.

4

Thank you for your replies. It confirms what I thought.

I really think we could achieve the same savings with a much cheaper restrictor if that’s the route corporate wants to go.

5

And corporate may want to rethink the whole thing if they think they’re getting 15% cost savings without flow restriction. Especially if they insist on the same unrestricted flow.

Because TANSTAAFL.

6

Twenty thousands dollars is a lot of money. So assuming that this isn’t a scam and that it really could cut 15% off your company’s water bill, what is the payback time? In other words, just how much water do you use?

7

About $10k/month worth of water + sewer. So simple payback = 1.1 years. Its a lot of water.

8

Water meters measure the amount that flows through them, not the pressure or the rate of flow.

So anything you’d put downstream of the meter would not actually affect the metered amount, except insofar as it reduces the amount that flows through the meter.

9

If your water meter is giving wrong readings, the water company should replace it. There are national and international standards for water meters, which do eventually wear out.

Like other measurement systems, water meters have an error curve. If the meter is used outside of specifications for flow, the measurement will be wrong, and the water company should replace the meter with an appropriate meter.

Water meters aren’t designed to measure sludge, scale, rust or air bubbles. If your meter is constricted, or if the water is full of air bubbles, the readings will be wrong, and the water company should correct the problems.

Water meters are built to cost and purpose. If there is turbulence, a meter might not work correctly.

Some water meters are sensitive to turbulence. I’m not a Chem Eng: I don’t have any feel for how big the error is. If your meter is giving wrong readings, your water company should replace it with one that gives correct readings.

I can conceive that a meter might read high, or low, if you are drawing so much water through it that the supply is incorporating air bubbles, or if it has been place on a pipe corner, and that it might make more sense for you to put in a flow restriction after the meter, instead of getting the water company to put a flow restriction after the meter.

The ‘smart valve’ website actually seems relatively sensible “It does so by keeping the water meter operating within its designed flow range”.

My personal opinion, as expressed above, is that if your water meter isn’t operating within it’s designed flow range, it’s a problem that should be addressed by your water company, at their expense.

And they are supposed to know about things, like how much it’s reasonable to pay, and what the best approach to fixing the problem would be.

But I’m not a water supply engineer and I don’t have the same supply company as you do.

10

What is the city water pressure. If it is below 60 psi then the special valve is saving money by being a restrictor to the water supplied to your building. If it is above 60 psi then after the meter some where in your building should be a pressure reducing valve (PRV). Normally it would be set at about 60 psi for a 1 story building. If you company wants to save water with a restrictor have the maintenance department drop the pressure setting on the PRV. Some simple thing to think about. If the special valve is reducing the amount of water by 15% by compressing the air in the water: then the volume of air in the water would have to be over 15% some where on the lines of 30 to 50%. Your are right someone is blowing a lot of smoke.

11

I don’t know anything about plumbing for large buildings but I once lived on the top floor of a brand new high-rise apartment. The plumbing in my unit made a horrible knocking noise, whether or not I was using it, and I complained about it repeatedly. But it wasn’t just my apartment; nearly everyone in the building complained about the plumbing noise. People started breaking leases. Reviews on the internet were scathing and it slowed down the growth in occupancy (though the noise wasn’t that bad).

It turned out, the also brand-new apartment manager reduced the water pressure to the building to try to save on water. Apparently, the lower water pressure caused the pipes to clang. Setting the pressure back to normal quieted things and reduced risk of pipes breaking due to excess vibration. The leasing agent (a cute young woman I used to flirt with) told me that water usage increased about 2% per leased unit the month after they raised the pressure to normal. So, all that bother, expense and disruption for trivial savings. The apartment manager did not last long.

This isn’t exactly the same as the miracle device you are evaluating but I would be wary of unfulfilled promises and unanticipated headaches.