Calculating potable water consumption 3

[ed_]

What factors should we consider when calculating potable water consumption per capita? what number is a good general rule of thumb and how is that number broken down?

How do we consider peak water demands and troughs throughout the day?

 

[SWComposites]

depends on the temperature and humidity.
if you are in the desert and its 100F+ outside, people need a lot of water to survive.

 

[IRstuff]

Typical recommendation on the demand side is 8 cups of water per person per day, but YMMV

TTFN (ta ta for now)
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[fel3]

//edited to make a bulleted list, which I meant to do when I first posted this//

There are too many variables to give a simple answer. As SW mentioned, climate plays a big role. In no particular order, so do:
[ul]
[li]Metered vs. unmetered systems. I have a copy of "Bulletin 166-4, Urban Water Use in California," California Department of Water Resources, August 1994. Per Bulletin 166-4, in the 1980s, Fresno (my city) had meters on 98% of commercial/industrial service connections and 11% on the residential service connections. Average annual water consumption for Fresno was reported as 284 gallons per day per capita. Clovis, which abuts Fresno, had meters on almost 100% of commercial/industrial service connections and 90% of residential service connections. Average annual water consumption for Clovis was reported as 218 gallons per day per capita. The difference in water consumption (66 gpdc, or 23% less for Clovis) between the two cities is mostly related to the presence or absence of water meters. The increased use of low-flow fixtures (see next bullet) has reduced both cities' water consumption and the increase in metering residential service connections in Fresno has helped even more. However, I don't have those numbers handy. BTW, I'm on a small flat-rate system on the edge of Fresno. About every three years, I drain and refill my swimming pool, which has a volume of about 23,000 gallons. Our water is hard and old water make it harder to maintain the water quality in the pool. If I was metered, I would probably stretch it to four or five years. Also, on the hottest and driest days of the year, I can lose about 0.6 inches worth of water to evaporation, which equates to about 180 gallons.[/li]
[li]Low-flow fixtures vs. standard-flow fixtures. This should be obvious: every flush, every shower, every whatever that uses water uses less with low-flow fixtures....except that it sometimes takes two flushes to properly clear a low-flow toilet.[/li]
[li]Parcel size, type of landscaping, and watering restrictions vs. no water watering restrictions for landscaping. Again, this should be obvious. In some cases, outdoor water usage can exceed indoor water usage.[/li]
[li]System leakage. Leaks add to the consumption totals even if the people don't actually get the water.[/li]
[li]System pressure. Some people use fixtures more in an on/off mode instead of adjusting the valve for a particular flow (I've seen it often enough, including with some of my grandkids). For any particular valve-open setting, you will get more water out of a high-pressure system than a low-pressure system.[/li]
[li]Demographics. I haven't studied this topic all that much, but you might start here:

https://www.nature.com/articles/s41... can potentially influence water consumption.

Also look at

https://www.epa.gov/watersense/statistics-and-facts

and

https://www.epa.gov/watersense/how-we-use-water

and

https://www.usgs.gov/mission-areas/water-resources/science/domestic-water-use.

[/li]
[li]The cost of water. Cheap water (especially when it's flat-rate priced) gets used more than expensive water.[/li]
[li]The type and extent of industrial uses connected to the system.[/li]
[/ul]

Diurnal water usage is system-specific, but most systems have higher water usage in the daytime than in the nighttime (a small system where most landscape irrigation is done at night might be the opposite....I've dealt with a couple systems like this). Daytime water usage sometimes shows a morning peak (before school and work), a mid-day peak (lunchtime), and a late afternoon/early evening peak (after school and work, landscape irrigation). Some industrial processes use water at a fairly consistent rate, 24/7. Some commercial areas might use almost all of their water during the daytime, with little or nothing at night. //Another edit: weekday and weekend diurnal patterns can be different as well.//

It's late in the day, so I'm sure I am missing something obvious. Unless you need to make some general statements about water usage, I suggest researching actual water usage data for your area.


============
"Is it the only lesson of history that mankind is unteachable?"
--Winston S. Churchill

 

[rb1957]

wouldn't the WHO have something on the matter ?

"Hoffen wir mal, dass alles gut geht !"
General Paulus, Nov 1942, outside Stalingrad after the launch of Operation Uranus.

 

[fel3]

rb1957…

Maybe not the WHO, but perhaps the Rolling Stones.

============
"Is it the only lesson of history that mankind is unteachable?"
--Winston S. Churchill

 

[LittleInch]

First define the usage.

"Potable water" means you can drink it. The issue is what else do you use it for?

Flushing toilets?
Washing people
Washing clothes or dishes?
Filling swimming pools?
Watering your garden?

Define that before you can even guess at an answer which varies hugely by location.

Remember - More details = better answers
Also: If you get a response it's polite to respond to it.

 

[ed_]

Hi fel3!

Thank you so much for your insightful response! I will read those links that you attached. I am focused on household usage so I believe it will probably follow the first trend that you mentioned regarding the peaks throughout the day.

Thanks for sharing your insight and expertise! It's highly appreciated.

 

[ed_]

Hi LittleInch,

For the most part I am considering water that is for drinking and basic household uses (such as in the kitchen and the toilet). The communities I'm studying are going to be less resourceful so they wouldn't be using water for non-essential things.
I will try to be more specific in the future.

Thanks for your advice!