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Measuring Water Use: Nitty-gritty

Courtesy MHYC

By Samantha Winter

What is a good way to measure one's daily water use?  Is there a gadget to attach to one's faucets to measure how much water is being used?

Cris Gutierrez, '77, MA '88, Santa Monica, Calif.

There is nothing like a cold bucket shower outside at 5:30 a.m. or a 2 kilometer walk with a 20-litre jerrican of water to help remind an American, like myself, of the gift of safe, fresh and easily-accessible water. After a recent long trip in East Africa, the slogan “Water is life” is fresh in my mind. Only about one percent of the Earth’s water is drinkable, and as Americans we use an average of 90 gallons of that water per person per day in our homes. That is 18 to 30 times the average daily water use of someone living in Sub-Saharan Africa.

Water conservation has several benefits including protection of natural resources, improved water quality in rivers and streams, and savings on water bills. But in a country where water runs so freely from the faucets, how do we keep track of how much we’re using?

Advances in technology have opened up the proverbial door, or in this context, valve, to a water-measuring gadget called a “faucet water counter.” Although I’ve yet to discover one of these counters currently on the market, the isave, which attaches to any household faucet or shower and runs on energy produced by the water flow, is the most anticipated water counter. Though the allure of a machine such as the isave is impossible to deny for a gadget-lover like myself, it will not provide a comprehensive picture of your daily household water use. You can find out your average daily household water use by doing some simple calculations with your water bill or by reading your water meter, but reading your bill or your meter won’t help you identify or fix wasteful and expensive leaks or help you figure out the activities that are costing you the most water and money.

The term “audit” can be a little intimidating if the first thing that comes to mind is an IRS agent with a calculator and a box of receipts. But unlike the notoriously terrifying tax audit, household water audits are fairly easy and can be done without the “help” of an outside agent. In fact, the most difficult part of a household water audit, in most cases, is trying to locate the manufacturer’s sticker on a washing machine or toilet cover.

I can honestly say there is nothing more satisfying or inspiring than watching a wide-eyed teenager eagerly lecturing his family about water conservation after he’s finished his first household water audit. With that being said, I’m willing to bet training youth and keeping their attention focused on the job could give even the Dalai Lama a couple of grey hairs. Which is why I am so grateful that a household water audit only takes about 30 minutes—even when a group of excited teenagers are the ones doing the work.

So take a breath and if you’re feeling patient grab your kids or the neighbor’s teenager and let’s walk through what you need and what you do.

What you need

Luckily, the tool list is relatively short and, with the exception of a hose meter, you probably already have everything on the list.

  1. A large measuring container – a large container of known quantity such as a five gallon bucket
  2. A medium measuring container – a medium container of known quantity such as a quart-size water bottle or a 2-cup measuring cup
  3. A stopwatch or clock with a second hand
  4. A tape measure
  5. A table to record your measurements
  6. A hose meter (optional)

What you do

When I worked with the youth we focused on six main appliances and/or fixtures—the toilets, the faucets, the showerheads/bathtub faucet, the dishwasher, the washing machine, and the hose.

  1. The Toilet – Some toilets may have the gallons per flush (gpf) printed on the underside of the tank cover, just behind the seat, or on the inside of the tank. But if your eyesight is as bad as mine or you’re working with a child who’s about to stick his head in the tank in search of the gpf it might be time to move on to these steps: 1) Open the back of the toilet, 2) Place the tip of your tape measure at the bottom of the tank and record the "full" water level, 3) Leave the tip of the tape measure at the bottom of the tank. Flush the toilet and read the water level when the water reaches its lowest level (hint: this is usually at the end of the flush), 4) Measure the length and width of the tank in back of the toilet. A quick note on toilets: When I conducted water audits in low-income households it was not uncommon to lift up the tank cover and discover one or more bricks stacked up in the water. While these "masonry masterpieces" may save money in the short term by reducing the volume of water used to flush the toilet, fixing a leaky toilet or investing in a low-flush toilet with save more money in the long run. This is particularly true if debris from those eroding bricks clogs the system and forces you to replace one or more parts of your toilet. If you do come across leaks in the toilet or in any other fixture and would like to take a stab at fixing them yourself, visit the EPA's Water Sense Website. The site also provides tips on checking for an identifying common household leaks.
  2. The Faucets - Many sink faucets have the manufacturer's flow rate in gpm inscribed on the aerator—metal or plastic piece at the end of the faucet. No information? Don’t panic. There is a simple way to measure flow rate manually: 1) Turn on the water, 2) Start stopwatch at the same time you place the medium measuring container in the stream of water, 3) when the container is full, stop the stopwatch, 4) record the size of the container and the number of seconds it took to fill the container.
  3. The Showerheads/Bathtub Faucet - Most showerheads have the manufacturer's flow rate in gpm inscribed in the center or on the outside of the showerhead. If not 1) Turn on the water, 2) Start stopwatch at the same time you place the large measuring container in the stream of water. In the case of a showerhead, make sure all the water is entering the container, 3) when the container is full, stop the stopwatch, 4) record the size of the container and the number of seconds it took to fill the container. Warning: If you are doing this water audit with a child, wear a raincoat. I have discovered after several unexpected showers that youth are absolutely tickled when given the opportunity to drench a fully clothed elder.
  4. The Dishwasher - You may be able to find the volume per load in the user's manual. If you do not have a user's manual or, as is often the case in my house, it is somewhere buried in a box you can’t find, record the model and serial number of your machine from the sticker on the inside of the machine, and look up the manufacturer’s specifications online. If both these options fail, use the average volume per load (9 gallons) for a dishwasher.
  5. The Washing Machine - As with the dishwasher you may be able to find the volume per load in the manufacturer’s specifications or by looking it up online. If not, the average volume per load for a washing machine is 41 gallons.
  6. The Hose - Measuring flow rate for a hose can be done with the technique described for the bathtub faucet. If you have the resources or the inclination, a hose meter can also be used to measure water use.

Okay, so you’re done with the majority of your audit. Make sure you record the number of times you used an appliance and/or the time you spend using each fixture. Now, let’s make sense of the numbers. If you are a hardcore math junkie you can crunch the numbers yourself using these instructions. Alternatively, you can input your findings and measurements into this spreadsheet (PDF). In addition, the information for your household water audit can be entered directly into the daily water use tool I discussed in the Essential Answer.

So now that you’ve got the numbers, what do you do to stop pouring so much water into your lifestyle? Clearly, telling your boss that you are abandoning email for post-it notes because your computer is doubling your water footprint is out of the question. And, no matter how tempting it is, forgoing clothes for a banana leaf is hardly acceptable in this country. Taking responsibility for your daily water use in the home, on the other hand, is a sensible, money-saving and effective way to start conserving the earth’s fresh water. But if you’re really excited about slashing gallons from your water footprint you can always cut back on your meat and dairy consumption, take your bike or walk instead of driving, and/or avoid those binge trips to the mall. Whether or not you decide to trade in your hamburger for a salad, the key to conserving water is not how many things you give up when you start, it’s simply to start.

Conducting a household water audit is the easiest and cheapest way to detect leaks and start conserving the Earth’s most precious resource.  And believe me, it’s a lot easier to spend an afternoon measuring and recording toilet dimensions than hauling a 20-liter jerrican for more than a mile, just to have enough to drink.

SAMANTHA WINTER is a graduate student in environmental engineering and science.



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