I promised in my original cloth diaper article that I would talk through the environmental and monetary impact of cloth versus disposable diapers since I know there’s a lot of debate out there about whether cloth is truly better. I will start today by going through the environmental impact and leave the monetary discussion for another time.

For the purpose of simplicity, I am only going to consider the carbon footprints of each method here. I know there are considerations around the waste water for washing cloth diapers and the environmental impact of disposing of disposable diapers. However, I cannot think of a way to make a true comparison of those two factors. After all, which is worse—using the water needed to wash cloth diapers or having disposables sit around in a landfill for hundreds if not thousands of years? Personally, I would argue that the latter is much worse, especially given that I live in a state that has plenty of water and we are on well/septic, so the waste water generally just goes into the leech field. Yes, the solid waste still gets pumped and goes to wherever solid waste from septic tanks go, but the same would happen if the babies were using a toilet.

So, we will compare something that is a little easier—pounds of CO2 emitted for each option. We’ll consider cloth diapers first. As I mentioned before, the babies go through about 15 diapers a day, and I wash every other day, so I’m washing 30 diapers at a time. For this wash cycle, I need to consider the pounds of CO2 emitted for the electricity to pump the water and then heat the hot water. I also need to consider the pounds of CO2 necessary to make the cloth diapers in the first place. Note that since we do hang all of the diapers out to dry, I am not considering the electricity needed to run a clothes drier. That could easily make cloth diapers a losing proposition.

We have an old washing machine, so it uses a lot of water—24 gallons of hot and 27 gallons of cold per cycle in fact. We have a ½ horsepower well pump that operates at 230V with a full load of 4.8A and a max load of 5.9A per the sticker on the interior control box. Unfortunately, it doesn’t tell me a flow rate, but let’s assume worst case scenario of 5.6 gallons per minute (the lowest flow rate I was able to find for a ½ horsepower well pump). This means that to get the 51 gallons of water to wash the diapers, the pump would have to run 9.1 minutes. Assuming it runs that whole time at its max load (it doesn’t or it likely would have died long ago), the kWh for pumping the water for a load of diapers would be (5.9 * 230 * 9.1)/(60 *1000) or 0.206 kWh.

Then we have to heat 24 gallons of water from 40F to 120F (where the water heater is set). Because I’m trained as a scientist, the first thing I do is convert all these measurements to metric. So my degree change is 44.4C and the volume of water is 90.850L. This makes the energy calculation pretty easy because 1 g of water is 1mL, and 1 calorie is the energy it takes to raise the temperature of 1 g of water by 1 degree Celsius. Assuming a water heater efficiency of 80%, this means we need (90850 * 44.4)/0.8=502275 calories for the hot water. Because I’m weird, I know that 1 calorie is 4.184 joules, so this is 2101519J. This seems like a lot until you realize that 1 watt is 1 J/s, so you would actually divide joules by 3600000 to get kWh (which is what all the utility companies in the US measure in). So we actually only use 0.584kWh to heat this water.

Using the EPA’s estimate of 1074.7 lb CO2/MWh delivered, this means we use 0.849lb CO2 for each load of diapers (Side note: The average dryer uses about 2.5kWh per cycle, or more than twice as much as all the energy used for washing —even in our super inefficient washer. So I definitely think air drying is worth it).

So how much CO2 goes into manufacturing each type of diaper? These numbers were surprisingly hard to find, so I eventually turned to the UK’s life cycle analysis study, perhaps the most complete comparison of cloth diapers to disposable diapers that there is (this is also a good place to go if you want to see just how tweaking your behaviors when washing cloth diapers can affect your environmental impact). Per table 7.1, a child being changed 4.16 times a day for 2.5 years (the average time in diapers) will go through diapers that take 490kg CO2 to produce and transport. This is 0.285 lbs of CO2 per diaper. Similarly, for 52.5 prefold diapers, the same study estimates 134 kg CO2 for these 52.5 diapers or 5.62 lb CO2 per diaper.

We change about seven times a day right now in cloth, but one thing the study does point out is that parents tend to change cloth diapers more often than disposables (I’ve read this elsewhere too, and it makes intuitive sense—disposables are more absorbent). They estimate an average of 6.1 changes per day for prefolds in the paper. So if I scale how many changes we would likely do were we to use disposables, I get 7/6.1 * 4.16 = 4.77 changes per day (honestly, this number is almost certainly higher since daycare is required to change them every 2 hours but we’ll go with it).

So now we’re finally ready to do the math. We only bought 24 diapers new (the rest were used), so that’s 135lb CO2. If the girls are in diapers 2.5 years, we’ll do approximately 456 loads of laundry which adds another 387lb CO2 for a total of 522lb CO2. For disposables, at 9.54 changes per day (remember, two babies), we would use 2481lb CO2, so we are keeping nearly 2000 lbs CO2 from being released into the atmosphere by our diapering choice. Another way of looking at it is that after just 29 days of using cloth diapers, we have already made up for the CO2 needed to manufacture those diapers by not using disposables.

Now, one could argue we definitely made some choices which contribute to the lower impact of cloth diapers, such as line drying and buying used. In fact, the paper I cite above concludes that the environmental impact of using cloth and using disposables is about the same. Of course, what it doesn’t really stress and probably should is that there’s not a ton you can do to change the environmental impact of using disposable diapers. But there is a lot you can do to lessen your environmental impact with cloth. In fact, I would argue that we’re still a long way from environmentally friendly with our diaper routine—after all, I still wash in hot water with an ancient washing machine (yes, we are considering changing that, but it’s hard to justify a new washer when the old one works fine). I’m sure there are many out there who have found ways to be even more efficient with their diapering workflows.