Some may call us crazy, but it was never really a question for us as to whether or not we were going to use cloth or disposable diapers. Ever since we started talking about having kids, we wanted to use cloth, even when we learned there were two babies instead of one. There was a brief moment when I considered relenting and going back to disposables right after we got home and I was somewhat hormonal and wondering how we would possibly take care of two babies, but Mr. BBB fortunately talked me down from my panic. For us, it came down to two main reasons:

1. Environmental impact—this was the most important reason for us. I know there is a lot of debate over whether cloth is more environmentally friendly than disposables or not (I will cover analysis of our own situation in a future post)
2. Cost—I read somewhere that a baby will go through 6000 diapers before being potty trained. For us, this would be 12000 diapers. I’ll analyze cost in more detail later, but it seemed unlikely that we would spend as much on buying and laundering cloth diapers as we would on 12000 disposables, especially since we bought some of our diapers used.

We have washed our own diapers from the beginning, principally because running the numbers showed that using a diaper service would mostly negate the previously mentioned benefits. Being the type of person who wants to know everything I possibly can as far in advance as I can (working on that), I did a lot of research before they were born on how to wash diapers. Most of the sources I read suggested that they needed to be washed in hot water. I dutifully did this for the first few weeks, mostly because I was sleep-deprived enough that I couldn’t do anything but execute on whatever plan I had developed before the babies were born. However, once things settled down, the scientist in me began to wonder if I really needed to use all that hot water. We washed all our other clothes in cold, and cold was obviously better for both the environment and our wallet (especially since we have a top loading washing machine from the seventies—still trying to decide if it’s worth it to get a new one). So I turned back to the internet. Most sources suggested there were three main reasons to wash in hot:

1. It was more sanitary
2. It removed poop from the diapers more effectively
3. It kept detergent from building up on the diapers which would leave them more absorbent and less smelly

 I decided not to test for the first point. For one thing, though hot water will certainly kill more bacteria than cold, if you keep your water heater at the recommended 120F, it definitely won’t sanitize anything. The only way to do that would be to autoclave your diapers or something similar, and that seems like overkill. For another thing, I really did not want to try and test this. The best way to do it would be to culture whatever was on the diapers, and I certainly did not want to see the results of that.

So I decided to test only the last two claims. Here were the four things I measured:

1. Smell- this was admittedly subjective on a scale of 0-10. 0 was no smell, 10 was the type of smell that might have activated my gag reflex before I became a mother.
2. How many times in a day one of the girls leaked through the diaper (my thought was that this would test not only how absorbent a diaper was but how quickly it could absorb)
3. If either of the girls got diaper rash
4. The number of poopy/stained diapers before and after I washed

Methods

I started by stripping the diapers to try and remove any detergent build up that I could. I did this by washing them in hot water with soap and then doing a second cycle without soap and adding a half cup of vinegar before the final rinse. Since we have about a four days’ supply of diapers and wash every other day, I did this for two wash cycles which should have ensured nearly every diaper got stripped.

I then washed only with cold water for the next two weeks. We typically launder diapers every other day which gives us about thirty diapers total in each load. Each of our diapers consists of an insert of some sort and a flat, i.e. a large cotton cloth (this is the type of cloth diaper they used in the old days). I washed in an old top loading washing machine that used about 50 gallons of softened water a cycle. I would add one ounce of this detergent per cycle. After the wash, I would hang the diapers out (preferably outside but if it was supposed to rain, we would hang them inside instead). We did have a couple days where the diapers did not get as clean as we wanted (possibly because there were too many on that particular day), so we had to wash a few diapers twice. I also ended up scraping some of the worst diapers to ensure they would get cleaner though I had originally intended not to do so since the girls are mostly breastfed (things will change once they start solids).

Once I had the data from our cold washes, I did another round of two washes with a strip cycle afterwards. Then, I proceeded to do two weeks of washes only in hot water (note that our washing machine does rinse with cold, even in a hot cycle). For this round, I did not actually have to scrape diapers in order to get them clean which was definitely nice.

The scientist in me does understand that there are some definite flaws with these methods. However, I was trying to balance getting the data I wanted with the need to not spend forever doing laundry and still actually use all the diapers. For example, I didn’t let diapers sit around longer in an attempt to wash the same number every time and we treated any diaper rash we found aggressively until it was gone (though we used the same treatment during both the hot and cold washing times–Bert’s Bee’s). I also acknowledge that we could test absorbency better by weighing a dry diaper and then soaking it and weighing it again. However, this would have required us to keep track of what diapers we were testing and ensure they were used and washed the same number of times during the hot and cold cycles. Honestly, that would have just complicated washing too much. Marking down a tally every time a baby wet through her diaper to her clothes was much easier.

Results

Below are tables of the results with cold water (first table) and hot water (second table). Since we did not wash every day, you will see that some days don’t have the before and after columns for washing. You may also notice that though we typically did laundry every other day, there are a couple times where we did it two days in a row or skipped a day. This was to try and take advantage of dry sunny days where we could hang the laundry out. As mentioned before, we sometimes had to sacrifice some of the science in order to make a workable workflow.  

Day	Diaper Rash	Wet Clothes	Smell Before	Smell After	# Stained Diapers Before	# Stained Diapers After
1	0	1	N/A	N/A	N/A	N/A
2	0	1	6	3	21	17
3	0	1	N/A	N/A	N/A	N/A
4	0	1	5	0	9	2
5	1	1	N/A	N/A	N/A	N/A
6	1	0	7	1	12	8
7	1	0	8	2	9	2
8	0	2	N/A	N/A	N/A	N/A
9	0	0	8	3	11	3
10	0	0	N/A	N/A	N/A	N/A
11	1	1	9	2	12	10
12	1	2	N/A	N/A	N/A	N/A
13	0	1	7	2	11	8
14	1	1	N/A	N/A	N/A	N/A

Day	Diaper Rash	Wet Clothes	Smell Before	Smell After	# Stained Diapers Before	# Stained Diapers After
1	1	0	N/A	N/A	N/A	N/A
2	1	0	7	0	11	2
3	0	1	N/A	N/A	N/A	N/A
4	1	1	N/A	N/A	N/A	N/A
5	0	0	8	1	6	1
6	0	1	N/A	N/A	N/A	N/A
7	0	0	7	2	7	3
8	0	0	N/A	N/A	N/A	N/A
9	0	1	7	1	10	3
10	0	2	N/A	N/A	N/A	N/A
11	0	1	7	1	11	3
12	0	2	N/A	N/A	N/A	N/A
13	0	0	6	1	5	1
14	0	0	N/A	N/A	N/A	N/A

For those of you who don’t want to do math, here are the averages:

Cold

• Average number of days with diaper rash (note if both babies had diaper rash, I would count that as 2 for the day, but it did not happen during the measurement period): 0.5
• Average number of wet clothes per day: 0.86
• Average smell reduction: 5.29
• Average stained/poopy diaper reduction: 5

Hot

• Average number of days with diaper rash (again, if both babies had diaper rash, I would count that as 2 for the day, but it still did not happen during the measurement period): 0.25
• Average number of wet clothes per day: 0.75
• Average smell reduction: 6
• Average stained/poopy diaper reduction: 6.5

This shows that the hot water performed better on every metric I measured. However, it wasn’t much better (though keep in mind that after the first disastrous wash in cold, I was scraping those diapers but not the hot ones–this should only have affected the stained/poopy reduction though). Is it statistically significant? Maybe. I honestly don’t have the time or inclination right now to dig out my stat book to remember how to calculate p values. If someone else is so inclined, go for it. Maybe I will do it when I have more time (ha!)

For now, I am continuing to wash in hot water given what I found here and because it’s the least amount of work. I’m still line drying, so I feel that more than makes up for the amount of energy used with a hot wash (I do plan to fully calculate energy usage later and will post the results). I have tried warm water a couple times, and it seems to perform just as well as hot anecdotally though I have not yet taken data on it. I also finally found a book which suggested cold water should work fine, so I am ordering the detergent they use to try that and see if perhaps it will work better in cold water. Mr. BBB and I have also talked about buying a second washer to be the backup to our 40+ year old machine, so perhaps that will change things as well.

All in all, there are many more experiments to be done, but I hope this helped at least some of you who, like me, were trying to figure out if the hot water diaper washing is really worth it.