How much water does it take to fill up a bathtub? How many gallons do you need to fill it up? What type of tub is it? Is there any way to tell if your bathtub has a plastic liner or not? If so, what kind of plastic is it made out of and where can I get one for my bathtub? Are there any other types of plastic liners that are used in bathrooms and why aren’t they included in the list above? Do you have any questions about these kinds of things?

If you answered yes to all of those questions, then this post is definitely for you! You might want to read through the rest of this page before continuing. But if not, let’s jump right into it!

The Bathtub Water Capacity Question

When you think about it, a bathtub is really just a big bucket filled with water. And when we say “big” we mean huge. A typical bathtub is about the size of a small car garage. That means that it takes a LOT of water to fill it up!

(And remember, that doesn’t even include the time and effort needed to clean up after ourselves!)

In fact, most people don’t realize just how much water goes into filling their bathtubs. According to the U.S. Geological Survey, a standard 10 gallon bucket of tap water contains approximately 1 quart of pure spring water.

A typical bathtub is at least three feet deep and two feet wide. That means that the amount of water needed to fill it up would be a whopping 3,333 gallons (10,000 liters) of pure liquid!

That’s enough water to supply a family of four for over five days! Even though most people don’t use their baths regularly, you’d still probably need to buy some sort of storage solution for that much water. That means that 10 buckets of tap water will fill up a 10 gallon bathtub. Still following?

Use only 5 gallon buckets when filling up bathtub for safety!

Now before you run off to the bathtub, keep in mind that this is just an estimate. Different brands of tap water have different amounts of clean spring water. (And yes, there is such a thing as “bad” spring water!) So how much is actually in your bathtub? Let’s go find out!

The average person takes 2 baths a week. That means they’d need about 50 gallons of water to use over the course of a week. If you’re really tight on money, there are cheaper and easier ways to store water.

The Average American Bathtub

Nowadays, most bathtubs are made out of a sort of fiberglass or plastic. These bathtubs are usually white in color and smooth to the touch.

How can I tell how much water is in my bathtub?

The first thing you need to do is find the capacity of your bathtub. For this, you will need to find the dimensions of it. If you don’t know these numbers off by heart, just measure them yourself with a ruler. (We recommend that you take the measurement from the outside of the bathtub because most tubs are not a perfect square or circle; they are more of a trapezoid shape.

You most likely have one in your own house. We’re going to use that as an example.

Let’s think this through for a moment. Most bathtubs are made to be incredibly durable and long-lasting. This plastic or fiberglass material is incredibly strong, more so than the wood which was used in older bathtubs. This means that it’s probably not going to break or crack easily.

Now, take the numbers you just found and multiply them together. (In other words, if your tub is 2 meters wide by 3 meters long by 0.5 meters deep then your capacity is 6 cubic meters). Next, you are going to have to guess how much water is in there right now.

The reason for this is simple: You want to measure how much water you can get out of the bathtub before it’s empty. It’s also not going to absorb water, which would add additional weight. That being said, the bathtub is probably not going to be weighed down by all of the water which is put into it. There should be no issue with it breaking or cracking if it isn’t full of water.

But what if someone jumps into the bathtub?

It’s not something you’d expect to happen on a regular basis, but what if someone accidentally falls into it? The water is also not very clean. You wouldn’t want to risk getting sick if you can help it, so you need to be careful about making sure no one falls into the bathtub. You’ll find that most bathtubs actually have a little bit of water in them when you first use them. (This amount varies from person to person and from tub to tub).

Let’s say yours has about 50 liters of water in it right now. Now, using the formula we learned earlier, you can find out how much water your bathtub can hold after you’ve drained it. (Remember to convert the cubic meters to liters by multiplying by 1,000! 6m3 = 6,000L).

Your answer is somewhere between 4,050L and 8,100L. This is quite a wide range, isn’t it? That’s because there are no exact values. The type of tub you have, for instance, will affect how much water it can hold. You might also have a tap that leaks a little bit of water over time.

That’s the thing about this project: There are a lot of variables. Most of them are impossible to control, but that’s not going to stop us from getting an estimate! Now that you have an idea of how much water is in your bathtub, it’s time to start draining it.

Step 3: The Draining Process

It’s time to get rid of all of that dirty water you have in your bathtub. Don’t worry; we’re going to find out exactly how much is in there. (You did measure it before you started draining it, right?)

First of all, you could just open the drain and let the water fall out. The problem with this approach is twofold:

a) It’s not very efficient. You’d have to wait around for the bathtub to drain, and you need to be doing other things (like hanging out with friends or studying for your exams).

How can you speed this up? Well, you could get a hose pipe and place one end in the drain. Then, you’d open the other end to the outside (outside your window would be best). This way, atmospheric pressure would push the water out. It should also be noted that this will take a while.

(Days, possibly weeks, depending on how fast you can get the hose pipe into the tub)

How else could you get rid of all that water ?

Well, you could try putting the drain plug in and using a bucket to scoop out the water. This would be faster, but it still isn’t the best solution. There are other, more efficient ways of draining water from the bathtub.

For one thing, you could get a pump and hook it up to your bathtub drain plug. The pump will do the job much faster than a bucket.

For another, you could completely remove the drain plug, then use the funnel to lower a hose pipe into the bathtub. Then, you run the other end of the hose pipe outside. As with the last method, atmospheric pressure will push the water out.

These are just some of the methods you can try using to get rid of all that water. Be creative and resourceful!

Step 4: Counting the Liters

Once you’ve drained all the water out of your bathtub, you need to measure how much is there. Remember, this value is going to be your answer. How much water was in your tub in liters?

Let’s say you got 4,200L out of your bathtub. Was this reasonable? It really depends on the size of your tub and how full it was when you started. What if you got 2,500L? Was this also reasonable? Again, it all depends on how full your tub was and other factors. You can’t really know for sure without repeating the experiment a few times to narrow down the range of possible values.

There is another way you can find out how much water your tub could hold. You could fill it up again and mark the level of the water (use a Sharpie to write “fill line” on the side of your tub). Then, you can keep adding water until it starts to overflow. How much more did you have to add to make the water overflow?

Well, if you mark 1L of water as 1mL and 1m as 100mL, then you can say that your tub could hold (4200/100)m L , or 4200m L of water. There’s your answer in terms of milliliters!

Predict The Volume Of Other Bathtubs

Of course, the story doesn’t end there. Your test bathtub was only one of many different types, but the information we have so far should be sufficient to predict how much water is held by other types of bathtubs.

There are two kinds of bathtub designs in common use. One is a traditional bath-tub shape with vertical walls and a flat bottom. The other, more modern design is more like a bucket with a hole cut in the bottom.

Let’s start with the first kind. As we found out during our experiment, the water capacity of this kind of bathtub increases linearly with volume. That means that if you double the size of the tub, then you can fit twice as much water inside. Furthermore, this should also hold true for any size reduction (e.g.

a quarter of the size of the original).

This is the volume formula we’re working with: V = BL3. The letters here stand for “Volume”, “B” stands for “length of the bathtub”, and “L” stands for “Length of the tub”. (It’s best not to get too attached to a and b; they’re just random numbers that represent the size of the bathtub. But L, or length, is a little different).

So this means a bathtub that is 1/4 the size of the original should have a volume of 1/2 * BL3.

Alright, how about the second kind? Well, we can immediately throw out any formula that has the length (L) as the width (W) or height (H). That would imply that the volume scales as LW*H, which doesn’t make any sense.

However, there is also a second kind of tub with the same shape as a bucket; it has vertical sides and a flat bottom which forms a right triangle.

For this kind of bathtub, the capacity should scale linearly with the area of the bottom. That means that if you double the size of the bottom, then you can hold twice as much water. Furthermore, this should also hold true for any reduction in size (e.g.

1/4 of the bottom).

This is the formula we’re working with: V = AW2. The letters here stand for “Volume”, “A” stands for “area of the bottom of the bathtub”, and “W” stands for “Width”. (It’s best not to get too attached to a, W,or L; they’re just random numbers that represent the size of the bathtub).

So this means a bathtub that is 1/4 the size of the original should have a volume of 1/16 * AW2.

Test it Out

Now, let’s test these out with real numbers to see which one makes more sense. Remember that your tub measured 4200mL.

You fill your bathtub up all the way and record this as V1. Then you use your Sharpie marker to write “FILL LINE” on the side of the tub right at the 4200mL level.

The “V” in this case stands for volume of water, or how much space is taken up by water. The “B” stands for the length, width, and height of the bathtub (length multiplied by width multiplied by height). The “L” stands for the length of the bathtub (not the length of water; that’s a different measurement). The “A” stands for the area of the bottom of the bathtub, while “W” stands for the width of the bathtub.

After some experimenting, you find that the first kind agrees with your experiments much more than the second kind. In fact, you’re able to fit more than five liters in a 4200mL tub. You can fit about 5.5 liters in there.

If you were to represent your ideas graphically, it would look something like this:

Since the first kind of formula agrees with your observations much better, you decide to throw out the second kind and stick to what works.

Now that you have an idea of the kind of volume you’re working with, it’s time to figure out a way to hold that much water.

A Water-proof bag?

You decide to look through your closet to see if you have anything waterproof. Unfortunately, you don’t have anything that’s completely waterproof, except for your raincoat. You remember that you got it for free after signing up for a bank account at your local bank branch.

You take a look in the dresser drawers and you find an old trash bag that should work.

Just to test it, you hold it under the faucet and turn it on to a low-medium setting. After a few minutes you see that the water has collected in the bottom of the bag. You turn off the water and give it a feel. It still feels fairly soft, so it should work for what you need it to do.

You turn the faucet on and off a few times and make sure that no more water is leaking into the bag.

Then you reach into the back of your closet and find a hair dryer that was given to you years ago but you’ve never used.

Perfect!

You bring everything out to the bathroom and lay out your trash bag on the floor. Then you remove the hot light bulb from the vanity light above the sink and lay out a few towels on top of the bag.

You then place the dryer on top of the towels, making sure that its nozzle is aiming toward the trash bag. You turn on the dryer and see that it’s working.

You step into the tub and wet your hair down. Then you begin pouring cup after cup of water onto your head, completely saturating your hair. When you have a good portion of it soaked, you step back onto the wet towels on top of the bag, soak it some more, and then pour cup after cup onto your hair.

After about five minutes of this, you reach your desired “wet” look. Your hair is now much flatter than usual and looks as if it has been styled with some sort of liquid. It doesn’t really matter, though. The only people who are going to see you are your sister and mother, and they’re not fashion critics.

You turn off the dryer and pull it out from under the towels. Then you bring the dryer and the bag out into the hallway with you. As you’re pulling the bag out with one hand, you accidentally let go of the towel rack, causing the towels to fall off of the rack, onto the floor…

right onto a small puddle of water on the floor.

__Sources & references used in this article:__

- How High the Apple Pie-A Few Troubling Questions about Where, Why, and How the Burden of Care for Children Should Be Shifted (MA Case – Chi.-Kent L. Rev., 2000 – HeinOnline)

https://heinonline.org/hol-cgi-bin/get_pdf.cgi?handle=hein.journals/chknt76§ion=57 - Finding meaning in the second half of life: How to finally, really grow up (J Hollis – 2005 – books.google.com)

https://books.google.com/books?hl=en&lr=&id=nyeXc-wSz9cC&oi=fnd&pg=PT15&dq=how+high+should+a+half+shower+wall+be&ots=WkO1eugUlk&sig=L_lSRpg08ogoxrPle_3QJ3vmlpE - How the full opening of the capital account to highly liquid financial markets led Latin America to two and a half cycles of’mania, panic and crash’ (JG Palma – 2012 – repository.cam.ac.uk)

https://www.repository.cam.ac.uk/handle/1810/242211 - Shower wall liner (J Williams – US Patent 5,435,021, 1995 – Google Patents)

https://patents.google.com/patent/US5435021A/en