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Comment by spurgu | Hacker News Reader

I would be very interested in seeing a breakdown of the amounts. You only drink maybe 1-2 liters per day. Showers and toilet flushes add to a fair amount but the majority has to be water for the plants and animals you eat.

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I'm surprised the figures for the United States vs United Kingdom are are so far apart (550 vs 150). These leads me to think much of the usage is water lost during transmission, or used in farming/industry rather than in the home.

Farming sounds very plausible:

http://www.onegreenplanet.org/news/californias-drought-whos-...

and something I never thought about: ".. humans drink less than one gallon of water per day, but a cow can drink up to 23 gallons of water a day."

Think about the sheer acreage in the USA compared to England and how much of the land is used for crops or livestock.

>> ".. humans drink less than one gallon of water per day, but a cow can drink up to 23 gallons of water a day."

They do weigh a bit more though. :) It probably ends up being ~2x-3x a human's water consumption by weight.

Rasing meat for human consumption requires a TON of water (and land)

It might also have something to do with climate. People in a warm southern US climate probably drink more water than people living in a more mild climate (UK).

Have a look at the center of the US on a satellite map and you'll see where most of our water is used.

For example, https://maps.google.com/maps?hl=en&ll=37.811411,-98.98613&sp...

(A bit east of Dodge City, KS. The circles are irrigated fields.)

Most other countries use washing machines with much less capacity and water ue (side loaders vs. top loaders), have different toilet flushing systems with smaller loads, and generally put a much higher premium on drinking water. If you compare the US to the UK, also take into account the very different climate. Due to the relatively tame and wet weather, there is almost no irrigation in the UK. Case in point: There is no place like Vegas, in the middle of the desert, with golf courses and fountains all over the place.

At home, I think it's showers by far (something like 7 gal/minute, you do the math), ~50 gal for dishwasher or washing machine, then on down. And yea, most of the water that you "consume" is probably consumed so far upstream (hah!) that you don't even realize it.

Edit: I looked up my original source and I had misquoted dishwasher, sorry about that. The source is:

http://fi.edu/guide/schutte/howmuch.html

* Washing machines are 40-55 gal/load

* Dishwashers are 15 gal/load

* Running a faucet is 3 gal/minute

>> ~ 50 gal for dishwasher

That one shocked me especially as someone who has never owned, and never plans to own a dishwasher. I probably use around 4 litres to fill the sink and wash the dishes, at most 3 times per day - which works out at around 3.1 US Gallons/2.6 imperial gallons.

As I corrected, 15 gal/load for dishwasher. So, coupled with the fact that a running faucet is 3 gal/minute, a dishwasher is better if you leave the faucet running while hand washing dishes, and take longer than 5 minutes.

I didn't see the correction. I don't know many people who run the tap when washing the dishes. Generally I plug the sink and spend 1-2 minutes filling it with water. It still seems to work out less but I guess it depends on how ofter you fill the sink/run the dishwasher.

I used to use a huge amount of water when handwashing by rinsing under flowing water. Soap tastes icky and some screw up your digestion. Its possible you're not rinsing under flowing water.

Also consider the ratio of sink size to dishwasher size, which is a fad/style issue. My kitchen sink doing a realistic sinkful of dishes only holds perhaps 1/4 the dishes my washer holds.

It seems difficult, although not impossible, to buy a non-energy star dishwasher which means less than 6 gallons per load.

One point that everyone seems to miss is the amount of soap and biomatter being flushed thru the pipes is a constant, no matter if you handwash and use 20 gallons or use a machine and only use 5 gallons. So I donno about sewer system efficiency given an intake flow that might be 4 times more or less dilute.

I can do one dishwasher full of dishes using about 6 gallons, or about 3 to 4 sinks full, each maybe 10 gallons, for a total around 30-40 gallons. I believe this estimate to be true... in the ancient years of hand washing and old fashioned tanks, I could use up all the hot water in a 30 gallon hot water heater after thanksgiving by the end of dish time. Now that I have the tankless that will never run out, even after a handwashing thanksgiving, ironically I also now have a dishwasher which means I use practically no hot water anyway. There are other benefits to the tankless of course.

Sewers probably already have a harder time with the other major household source of solids.

Washing by hand is always worse.

> It still seems to work out less but I guess it depends on how ofter you fill the sink/run the dishwasher.

No, it's not less. It's more. A dishwasher can hold a lot more dishes than a sink.

>> " A dishwasher can hold a lot more dishes than a sink."

You put unclean dishes in the sink, wash them, take them out, and more more unclean ones in. The only limit to how many dishes you can put through the sink is how dirty the water gets which depends on how dirty the dishes are to begin with.

And no matter how good you are at it, a dishwasher does it with less water.

A modern dishwasher uses ~5 gallons:

http://www.energystar.gov/index.cfm?c=dishwash.pr_crit_dishw...

Or down to 1.5 gallons http://www.topten.eu/?page=freestanding-2

That 50 galon number is wrong. With a modern dishwasher (at least the ones sold here in Europe) you will always use less water than hand-washing, since there is massive re-circulation of the water in the dishwasher.

Do you not rinse the dishes?

It is thought (I dont know if it is true) modern dishwashers are more water efficient than hand washing. It has been repeated to me before. Might be an urban legend.

4 litres is a low estimate. Think of 4 1-litre cartons side-by-side; that's barely enough to submerge a plate. Some people may use that little water when washing up, but most use more.

The most efficient dishwashers sold in the EU use down to 6 liters per wash. http://www.topten.eu/?page=freestanding-2

Does 'at home' include watering the lawn or garden? If the drought in California is a 'mega drought' like some news outlets are saying, I hear that cities could pass laws restricting residents from watering their lawns as it accounts for up to 50% of a household's water usage [0].

[0] http://www.dailynews.com/general-news/20140125/megadrought-c...

This has happened in Australia in the past, in capital cities. You can get reported for watering your garden on the wrong days.

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