Which Conserves More Water, a Shower or Bath?
Water is not a finite resource, but potable water, the water we use to drink, irrigate crops and bathe in is. Which is why water conservation is so important. In this article we answer a question as old as bathrooms themselves - which conserves more water, a shower or bath?
The average US household uses 70% of its indoor water in the bathroom. Of that percentage, the majority of water is used to flush the toilet and bathe. The per capita water usage of the linked surveys is off, but the percentages seem accurate.
Since one of the highest household uses of water is bathing, it’s a good place to start conserving water in your home. So, we know from the statistics that most of you prefer taking a shower to a bath. But, for those who are curious, or may currently prefer to bathe, we answer the age old question of shower vs. bath and throw in a few water conservation tips along the way.
First, lets start with some facts on what constitutes the average bath tub or shower head. I generated the statistics below using numbers I found by selecting a wide assortment of products on various home improvement retailers, and bathroom product manufacturer sites.
The average bath tub holds 42 gallons of water. Some larger tubs, sold as garden, soaking, or whirlpool tubs hold 80 gallons or more. So assuming you fill the tub to the overflow valve, you’ll use 42 gallons of water. Lets assume most people stop just short of that point and fill it with 38 gallons of water.
The average shower head is rated at 2.5 gallons per minute, or gpm. The average person showers for about 8 minutes. Bringing the water usage of an average shower to 20 gallons.
So in the average home, the shower conserves more water than the bath.
Is my Shower Head or Bath Average?
Most modern shower heads will have the gpm rate printed near the nozzle. If it’s not printed there, chances are it’s an older or designer shower head and has a rate exceeding 2.5gpm. You can determine the rate of flow by taking a gallon bucket and placing it under the shower head. Turn the shower on and see how many times in a one minute period that you have to empty the bucket. That is your gpm.
The average bath tub is 60 inches long, 32.5 inches wide, and 9.5 inches deep (measure depth only to overflow height). Use a tape measure or ruler to get the dimensions. You can estimate the volume of your specific tub by using the formula below. Since tubs are not perfectly rectangular, this measurement will not be exact, but it will give you a good idea of the tubs water volume.
Average is Good. But, You Can do Better!
If you have an above average sized tub, consider filling it with less water when you bathe to conserve water. If you are in the market for a new tub, purchase a smaller one to replace it.
Although the average shower head sold today is 2.5gpm and considered low flow, it’s at the high end of the low flow. Newer technology allows for luxurious shower heads that use as little as 1gpm. They even sell low flow shower massagers now.
In all but the most extreme circumstances, the shower beats the bath tub in water conservation. Even if you have a high flow shower head, you can shorten the length of your showers to conserve water. Better yet, you can replace that high flow with a low flow model. There’s nothing wrong with taking the occasional bath for relaxation. However, given the facts I have to recommend showering as your primary form of bathing for the water’s sake.
Smaller tub? Small tubs are useless. I got rid of my shower-tub combo for that reason. You can’t bathe properly in them. Japanese traditional style of reusing water in a good deep saoking tub is my idea of a bath…clean yourself beforehand.
But since I can’t do that (Condos have limitations), I have a bucket with me in the shower. Catches some of the water; this is then used to water the patio garden.
another important note that isn’t done in the quick math is that if you have an average tube and average shower head then a bath is the best bet if you are going to be in there for over 15 minutes. I don’t know about everyone else, but on days where I am not late for work 15+ minutes of bathing is pretty common.
also agree w/ Sam-Hec, smaller bathtubs are worthless, unless you are a very small person.
@Sam-Hec - Point taken on the smaller tubs. Catching excess water in a bucket is a good tip. Traditional Japanese bath tubs, Ofuro, were created in a time when getting water wasn’t as convenient as turning a knob on a faucet. It’s the technology in my opinion that has made some of us wasteful. We could learn a lot from our ancestors.
@ T.J. - I have a garden tub in my house, at just under 6 foot, it’s really just big enough. So I know where your coming from, a smaller tub is definitely not an option for everyone. You’re right, if you take a 15 minute shower with an average shower head, you might be just as well, or better off taking a bath. However I’d hope if you like to take long showers that you’d eventually invest in a low flow shower head. It’ll pay for itself in time, and you get to take your long showers and reduce your impact.
Thank you everyone for the insightful comments so far.
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Was reading elsewhere (the great Augunomics.com blog) that, while the bathroom is where the water is used indoors, the lawn and garden is where the household uses the majority of the water, with outdoor use constituting 53% of the entire household’s water use.
Therefore, his bottom line advice was: Don’t worry about low-flush toilets — replace your lawn with plants that can live on local precipitation.
Now, I think any tweak you can make is going to be beneficial, but it seems clear from the numbers he shows that reducing or eliminating lawn watering and even garden watering, is going to be most beneficial.
http://aguanomics.com/2008/07/household-uses-of-water.html
@Mike Kole
You’re absolutely correct that outdoor irrigation water usage dwarfs bathroom water usage, in households that have lawns. I chose to write about the shower versus the bath because it’s a wide topic that everyone can relate to.
Only 63% of Americans live in single family detached homes, and not all of them have lawns. A large percentage of people rent, or live in condominiums that have common areas which they have little control over the watering of. 99% of Americans have indoor plumbing.
There are further complicating factors, such as not all irrigation is done with potable water. For instance, here in Florida a great deal of our irrigation is done with gray (untreated) water. As such, not all irrigation wastes potable water.
I do agree that lawns are a big water waster, perhaps the biggest. But, it’s not a simple topic by any means. For instance, if I have a brown spot on my lawn, I can be fined hundreds of dollars by my community. If my lawn dies, it could cost thousands. If I had my way I’d pave my lawn, or replace it with drought tolerant plants.
Everyone has the option of changing out their shower head to a low flow shower head, or choosing to take a shower instead of a bath. Not everyone has a lawn or control over it.
Don’t you love those cities? Fined if your lawn turns brown, but fined if you water too much (or on the wrong day, etc.)?
Our addiction to grass is silly. There are so many ways to landscape our spaces- for those of us with single, detached homes, that is.
@ Mike
You summed it up perfectly. Thank you. Hope to see more comments from you in the future!
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Of course I have to agree that shower saves more water compared to using bathtub. In fact the 8 minutes that you mentioned here not necessarily means that the tap has to continue turned on and we can just shut it off during the time we do scrubbing and applying soap.