water usage rates

I was born in L.A. in the 80s, during a bad drought. My parents drilled it into my brothers and me to conserve, conserve, conserve our water. I took baths with my brothers, my mom let her lawns go yellow and dry, and I got yelled at by my dad whenever I washed my hands for longer than a few seconds. And we never got to play in the water during hot summer months.

I also remember there was a public service announcement ad which ran on tv during my childhood that flabbergasted me. In it was a simple animation of a kid in a bathroom brushing his teeth and letting the sink faucet run water all the while. Right outside the bathroom was a small pond with a fish in it, and the running sink drained the pond nearly dry. Even now I don’t understand. What in the world do people need to run their sinks for when they’re standing around, brushing their teeth?

Currently L.A.’s water resources are running low, impacted both by low rainfall the past few years and an expanding population.

With all this history, I like to be aware of how much water I’m using.

So when one issue of National Geographic came, it didn’t have the usual Nat Geo map insert but an advertisement by Dow for something called Blue Planet Run 2007. Dow also included some numbers about water usage.

(2007? Wow, it took me a long time to get around to writing this entry!)

Some facts (or claims?) they list about water usage:

  • A shower can use 25 to 50 gallons of water.
  • Leaving the water running while brushing your teeth can waste up to 5 gallons. [GRRRR ARRRRGH]
  • The average full-tub bath takes 36 gallons.
  • One flush of toilet uses as much water as the average person in the developing world uses in a whole day.

That last factoid was something I already knew. It makes me feel guilty sometimes when I flush the toilet. With just one simple flick of the toilet handle, I essentially toss out clean water, about the same amount of water that some other people have to walk miles for, carrying buckets of water back home over a number of trips, in one day. And I flush multiple times a day! But then I remember back to when I was a kid and learned the rhyme, “if it’s yellow, let it mellow, if it’s brown, flush it down.” (Shudder.)

The other numbers made me curious, what were the flow rates of my family’s faucets? Over the years we’ve bought different faucets and installed water limiters on a couple of them. So exactly how much water came out of these fixtures?

My procedure was to turn on the faucet full blast and see how long it took to fill a four-pint container. (Equal to half a gallon.) This isn’t entirely scientific because I didn’t repeat my procedure enough times to get a good range of data. But I’m not doing this for science, it’s just out of curiosity. (I’d say my numbers are accurate within two more or less seconds.)

The results:

  • kitchen sink, which is the newest faucet in the house, 20 seconds
  • my bathroom sink, the oldest faucet, also has a water limiter, 23 seconds
  • my brother’s bathroom sink, the second-oldest faucet, had a water limiter but my brother switched it out, 20 seconds
  • my parents’ bathroom sink, newer than the previous two faucets, it’s upstairs so my mom thought the pressure difference would influence the time, 21 seconds.
  • the shower in my parents’ bathroom, 32 seconds
  • the bathtub in my parents’ bathroom, 4 seconds
  • the hose outside, 2 seconds

Basically, the faucets all run about the same rate except for my faucet being a tiny bit slower. (My mom was kind of upset with the new kitchen faucet, because the lower flow takes her more time to fill the sinks to wash dishes. I never timed the old faucets to compare.)

According to Dow, 5 gallons would be wasted from our faucets if we brushed our teeth for 3 minutes and 20 seconds. That’s a healthy duration; dentists recommend about 3 minutes. But that’s if the water is running full blast, both hot and cold. Nevermind why someone runs the water while brushing their teeth, why would someone run the water full blast?

Moving on, our shower runs a lot more slowly than anything else in the house. It’s a water-conserving shower head, most likely. But this just further proves my point about why I don’t use the shower: it takes forever to rinse the shampoo out of my full head of thick hair. Double that time now, too, since I started using conditioner.

(Ideally I would like a shower head with variable rates of water flow, from high enough to rinse out my hair within seconds, to turning off the water without having to touch the handles which I’ve adjusted to exactly the temperature I want. :P But my brother likes the shower head we have, and he uses it most often.)

The rate of water flow from the bathtub faucet by itself doesn’t mean much. Regardless of how high or low the water flow rate is, the tub is going to be filled to the bather’s liking. But what I did do with the information was time how long it took to fill my bath, then multiply by the rate of flow to find out how much water I use in my bath.

What I found out was that I obviously don’t turn on the water full blast when drawing my bath. It’s somewhere more like 50% to 75%, which takes 5.7 seconds and 4.6 seconds, respectively. Not too drastic a difference, but for the sake of simplification I’ll go with 5 seconds to fill half a gallon. At that rate, and about 3 minutes and 10 seconds to draw my bath, I use 20 or so gallons.

(Yes, I draw very shallow baths. I don’t like showers and love baths, but not at the expense of “36 gallons,” according to Dow’s average. Don’t worry, I’m an environmentalist. I suffer for Mother Earth.)

A 20-gallon bath would be less than Dow’s numbers for a shower, but my shower head is water conserving. A 15-minute shower in my house would use up only 15 gallons. We could take a luxurious 20-minute shower and still only use about 20 gallons!

Of course, if I have to spend those 5 extra minutes rinsing out my hair, and cursing the shower head all the while, I don’t see the point. (Yes, I suppose I did go through all this data gathering to justify why, in L.A., I choose water-hogging baths over water-saving showers. *grin*)

I gathered the last datum just on a whim. I’d measured every other water fixture in our house, why not the one outside, located at the very source? (That being the water main.) I expected it to be about the same as the bathtub, I mean the hose isn’t all that big. But surprisingly, the tub faucet’s flow rate is twice as long for the same amount of water!

What could I extrapolate from this information that would have some significance? We don’t use the hose to water the gardens, but we do use it to wash our cars. Aha! So at 2 seconds to fill half a gallon, or 4 seconds for one gallon, letting the hose run while washing the car for say 10 minutes would use up 150 gallons. 150 gallons! That would provide enough water for 100 people in third-world countries!

Don’t you appreciate having running water in your home so much more now? Doesn’t it make you want to use it wisely, so we don’t run out of clean water in the future? I sure hope it does.