Do low-flush toilets actually save water?

Cecil's Columns/Staff Reports
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Do low-flush toilets actually save water? I blew my nose on toilet paper — better to flush it or throw it in the trash can?

The question Cecil didn’t address, and the one I wonder most about is: Why should we be concerned with “saving water” in the first place?

It’s not as if the water simply disappears, once we flush. The entire water system is a closed loop, whether mankind closes the loop (as on the space station or in some municipalities) or whether nature finishes the job (through reintroduction of treated wastewater into the ground, where it undergoes more natural filtering to become groundwater again.)

It’s always seemed to me that the real issue isn’t wasting water but wasting the resources needed to transport the water, or to treat wastewater. Now, there’s no debate as to whether excess flushing requires the transporting of more water, but I think it is debatable as to whether it takes fewer resources to treat a larger quantity of cleaner wastewater, or a smaller quantity of dirtier wastewater.

Using the same (dubious?) logic as that behind the Laffer curve, “wastewater” that is 0% clean water takes no energy to treat (there’s no clean water to extract!) and “wastewater” that is 100% clean water takes no energy to treat. In between, water treatment is an energy-consuming activity, with various levels of efficiency. I seriously doubt that the current standard of 1.6 gpf was arrived at in consideration of these efficiencies, though I’d be delighted to find out that I’m wrong.

Given this analysis, does it really make sense at all to talk about “saving water” or does (as I suspect) that stem from a gross misunderstanding of the water cycle? At best, it seems we’re merely wasting the water pressure required for transport, and at worst we might be wasting energy in treating wastewater with a sub-optimal ratio of clean water to waste. Either way, water itself is certainly not being “wasted” in any meaningful sense.

-Bill

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[QUOTE=wclark_xoom]
Do low-flush toilets actually save water? I blew my nose on toilet paper — better to flush it or throw it in the trash can?
It’s always seemed to me that the real issue isn’t wasting water but wasting the resources needed to transport the water, or to treat wastewater. Now, there’s no debate as to whether excess flushing requires the transporting of more water, but I think it is debatable as to whether it takes fewer resources to treat a larger quantity of cleaner wastewater, or a smaller quantity of dirtier wastewater.

[/QUOTE]

I read somewhere that a drop of wine in the sewer is sewage, whereas a drop of sewage in the wine is also sewage.

My point being that it doesn’t matter much how dirty the wastewater is, it’s all got to be treated. (It may happen, but I’ve never heard of plants having to add fresh water to sewage to facilitate treatment.) So far, I don’t believe there are any public full-reuse water treatment plants in the U.S., so all wastewater eventually ends up evaporating into the air, seeping into the ground, or flowing into the ocean. In other words, once it goes down the drain, it’s gone until it comes back around as rain or snow.

If your community gets all the water it needs from rain and snow, that’s great. A lot of communities in the U.S. don’t, so they have to pipe water in from elsewhere, and in some cases “elsewhere” is starting to run out of fresh water, too. Populations are rising. Water from snowmelt is decreasing. Aquifers are drying out. We’ve got rivers in the U.S. that nearly disappear before they reach the coast. For whatever reason, there is just less fresh water to go around than there used to be.

When the fresh water runs out, the options start to look very expensive. The options I can think of are total reclamation treatment and desalinization. Along with that you’ve got to have pumps and pipelines to move the stuff uphill to your reservoirs, and heaven knows what else.

So the bottom line is no, by flushing less you do not really “save water.” What you do is save energy, which amounts to money. Look at it this way–water from rain and snow is purified almost entirely by solar energy–lots of solar energy, whole oceans full of it–that we get for free. If we use all that up, we’ve got to pay for any additional clean water out of our own pockets. Maybe it can be done, but we already seem to have trouble paying for all the other stuff that has to be done.

A gallon saved is a gallon earned.

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[QUOTE=wclark_xoom]
The question Cecil didn’t address, and the one I wonder most about is: Why should we be concerned with “saving water” in the first place?

It’s not as if the water simply disappears, once we flush. The entire water system is a closed loop, whether mankind closes the loop (as on the space station or in some municipalities) or whether nature finishes the job (through reintroduction of treated wastewater into the ground, where it undergoes more natural filtering to become groundwater again.)

-Bill
[/QUOTE]

Because the water cycle operates slowly. Many aquifers are being depleted faster than nature can refill them, and this will inevitably have some very bad effects.

RR

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[QUOTE=wclark_xoom]
does (as I suspect) that stem from a gross misunderstanding of the water cycle?
[/QUOTE]
Read up on “aquifers.”

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Central NC, among other places in the SE US, is now in the midst of a drought; a few months ago I heard on the news that the drought here was the worst in 113 years. The water that we flush down the drain, or even use to water the grass and garden, does not magically reappear as drinkable water in a day or two. Falls Lake, which supplies drinking water for Raleigh and nearby towns, has been steadily shrinking since last summer (although the rain we had last Tuesday and are having today is finally helping somewhat) to the point where land that has been covered for decades is now exposed.

A friend of mine who lives nearby in a more rural area is dependent on a well for her water, and that well is running dry. If things don’t improve soon, she may not have water to flush her toilet with, much less do her laundry or dishes.

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Not to hijack, but what I’d like to know is what is better for the environment (not necessarily just the water portion), throwing something out, or using the garbage disposal? I’ve never received a good answer to that.

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If they’re like a lot of low-flush ones, they save no water at all, since it takes 2 or 3 flushes to do the job fully.

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Dual flush toilets are fairly standard here nowadays.

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[QUOTE=MLS]
If they’re like a lot of low-flush ones, they save no water at all, since it takes 2 or 3 flushes to do the job fully.
[/QUOTE]
According to the column that this thread is based on, that’s not true.

As an aside, here (warning: PDF) is the most recent edition of the testing that was mentioned in the column.

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[QUOTE=Cervaise]
Read up on “aquifers.”
[/QUOTE]
A good place to start is this column of Cecil’s from last year: How come if you dig down far enough, you hit water? Where does that water come from?

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Yeah, it always really bothered me that environmentalists bitch about water conservation. Of all the things they want to take away from me because they say they’re non-renewable, they really show their true colors with water. Water is the ultimate renewable resource. It freaking falls from the sky like mana from god! And I can’t even enjoy THAT? Obviously environmentalists just hate me consuming anything.
Of course some places have droughts and some places are exhausting their aquifiers, but many places, like my home, New York City, get it from god-given rain. So why the hell am I not allowed to flush my shit with as much renewable water as I’m willing to pay for? And the worst part, the thing that is most irrational of all, is that in the places that are drought-ravaged or whatnot, the water doesn’t get spent on flushing toilets. The VAST majority goes to irrigation of crops and lawns. Flushing is a drop in the bucket. Herpes on a dead guy. So WTF. Leave my shit alone!
But actually I’ve started to think that water conservation is a line of bullshit that is made up and endorsed not so much by environmentalists but by local governments and utilities who are just too fn lazy to build new infrastructure. They’re happy as cows to solve their headaches by outlawing water use while looking like they’re doing the right thing. Environmentalists just buy up the propaganda and love the fact that there is one issue on which government is being active.

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:rolleyes:

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[QUOTE=Cervaise]
:rolleyes:
[/QUOTE]

Well said.

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[QUOTE=MLS]
If they’re like a lot of low-flush ones, they save no water at all, since it takes 2 or 3 flushes to do the job fully.
[/QUOTE]

As I said in the other toilet thread, my low flow is far more effective in emptying the bowl in one try than my previous 7 gallon model.
I was very pleasantly surprised to find this to be the case.

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Nobody mentioned septic tank systems (of which I’m a member). Big difference then flushing to town hall.

Andy