Thursday, January 15, 2015

Do this, not that! The water dilemma

Question # 1

A friend recently asked if it's better to waste a cup or use the water to clean a reusable thermos every day. We are in California, which is experiencing an extreme drought, so conserving water is top of mind for all of us.


Technically, yes, using a disposable paper cup uses less water than washing a thermos, but only at an extremely local level. If you look at the larger picture, it takes a half gallon of water to make the cup (plus more water to make the sleeve and the lid). Let's just round off the numbers and say it takes about 1 gallon of water for your average starbucks cup.

By comparison, washing the thermos by hand should use less than 2 cups of water (let's estimate it at 1 cup of hot water for soaping and 1 cup for rinsing) or about 1/8th of a gallon.

What if you use a dishwasher? Modern dishwashers use about 4 gallons per load (older models use about 6 gallons) and can fit anywhere from 30 to 50 items (not including utensils). Even using the more conservative numbers, if you only run the dishwasher when you have a full load (and I know you do!) that's about 1/5th of a gallon per item (30 items per 6 gallons is 5 items per gallon, so 1/5th gallon per item).

Still way less than the paper cup!!

Of course, there are many, many more reasons not to use a paper cup. They use huge amounts of petroleum to make, they are covered in plastic to make them waterproof, they can't be recycled and there are potential issues with composting them. But here is one new reason I came across when researching this article.

Every time you use a paper cup you are supporting the Koch brothers.

Holy crap! That's a shocker, right?! The Koch brothers, the billionares that fund the extreme wing of the Republican Party, aren't just in the oil business. They have an entire empire of evil including oil, chemicals, synthetic fertilizers, mining, and, yes that's right, paper products. Their subsidary, Georgia-Pacific, makes cups, plates, napkins, towerls, and toilet paper. Support democracy and forgo the paper cup!

Question # 2

This spawned a related question: How many gallons of water does it take to make a paper diaper versus wash a cloth diaper?


Okay, so this is a trickier question. In the first analysis, we basically ignored the amount of water used to create the reusable thermos because the average person only needs one thermos over the course of his or her lifetime. This means that the environmental costs of the mug are amortized out to nearly nothing.

Things are a little different with diapers. For cloth diapers you might need 5 in a day (so maybe 40 total diapers to get you through the week till you have enough for a load of laundry) and will only use them for 2 or 3 years. In this case, it might make sense to include the water used to make the cloth as part of the analysis. If you threw away the diapers after your toddler is potty trained, then cloth diapers actually use more water.

But let's assume that you plan to use the same cloth diapers on the next child and then after that as rags for cleaning around the house. This allows us to disregard the amount of water used in growing and manufacturing cotton (which is actually a darn lot of water!). Now we are left only with the amount of water used to clean the diaper. The average washing machine uses 40 gallons per load (15 gallons if you use a high efficiency, front loading washer). Let's also assume that you fit all 40 diapers in to that one load -- that's about 1 gallon per diaper.

How about the disposable diaper? I found a UK study that calculated the total amount of water used to manufacture all the diapers a child needs (4,200 diapers assuming 2.5 years and 4.6 changes per day). Its about 34,000 kilograms, so that works out to about 2 gallons per disposable diaper.

Based on these assumptions, the cloth diaper wins!

Of course, there are a number of other reasons to use cloth diapers. Disposable diapers are made with tons of nasty chemicals, use non-renewable resources (we're looking at you, petroleum!), and so on.

Beyond just the absolute amounts of water or energy or chemicals, I'd like to make a pitch for reusable products. Forgoing disposables makes us think more about the consumer products we buy: how long they'll last and what we'll do with them when they're no longer of use to us. It's a fundamentally different frame of mind that I think is better for our health and for the environment.