How Long Does It Take to Fill A Bathtub?

After a tiring, cold day, nothing can be more relaxing than a nice hot bath. However, to do that, you first need to fill a bathtub with hot water, and that will take some time. It is also good to know that your bathroom is one of the places in your house that consumes the most water, especially when you are taking a bath or a shower. But regardless of that, if we decide to take a bath, we want to know how much time it will take us to fill a bathtub fully? Let’s talk about that!

How Long Does it Take to Fill the Average Bathtub? It takes around 5 to 10 minutes to fill up an average size bathtub. However, this depends on the size of the tub, water pressure, and the size of the faucet from which the water leaks into the bathtub. An average bathtub with 60 gallons and a flow rate of 5 GPM needs around 10 minutes to fill.

Most bathtub faucets run water anywhere between 4 to 7 gallons per minute. Therefore, if your home has good water pressure and solid plumbing, you will quickly fill up your bathtub.

If you think that your bathtub is filling up too slowly, there is a reason for that, and you can fix that. Usually, there may be a problem with the plumbing connection in your home or something to the water supply in your area. However, this problem can be solved. In the next section, we’ll see what factors affect the bathtub’s filling time and what are the most common issues.

Most common bathtub sizes and the time it takes to fill them:

Bathtub Size:Filling Time:Flow Rate (m3/s):Type of Bath:
30 Gallons (113 liters)5 minutes4 to 7 gpm (lpm)Xsmall
40 Gallons (151 liters)6.5 minutes4 to 7 gpm (lpm)Small
60 Gallons (227 liters)10 minutes4 to 7 gpm (lpm)Medium
80 Gallons (302 liters)13 minutes4 to 7 gpm (lpm)Large
100 Gallons (378 liters)16.5 minutes4 to 7 gpm (lpm)XLarge
Table: various sizes of bathtubs and time it takes to fill them up. (gpm – gallons per minute)

If you saw this table and still think that your bathtub is filling way too slowly, you should talk with a licensed plumber and see how you can fix this issue. The average bathtub volume is around 40 to 60 gallons, and bathtub faucets on the average run at 4 to 7 gallons per minute. That is why it takes from 5 to 10 minutes to fill up an average-sized bathtub. Looking at this table, you can see various sizes of bathtubs and how much time it takes to fill them up.

Note! You can use a stopwatch to measure time more precisely.

How to Calculate The Time to Fill the Bathtub?

The best and most accurate way to measure the volume of any bathtub is to use a mathematical formula. For that, we’ll need parameters such as; bath length, height or depth of the bowl, and the width of the bowl. However, this formula will only give you approximate results. If you want to get accurate measurements, you’ll need to go into the field of integral calculations. For an average person, it is enough to use a simplified formula.

Bathtub Volume Formula:      V = H x L x S [m3]

  • V – the volume of the bathtub,
  • H – the height of the bowl,
  • L – the bath length,
  • S – the width of the bowl

Now that we have a bathtub volume, we need to calculate the time it will take use to fill a bathtub. The formula for calculating the time is the following:

Bathtub Time Formula: T = V * F [min]

  • T – the time to fill up the bathtub
  • V – the volume of the bathtub
  • F – gallons per minute (we take 6 GPM)

If bathtubs are designed differently (have different volumes), then the volume calculation requires a different formula. For example, we have a spherical model of tubs.

The volume of rounded bathtub is calculated by using the number π

To calculate the volume for spherical models, you will need to use the number π (3.14). It differs from other calculations because you need to calculate the semicircle area and multiply it by the length/depth (depending on the shape). After that, the formula is the following:

V = π * H * L * S.

What If It Takes More Than 10 Minutes To Fill?

For a bathtub with approximately 60 to 70 gallons of water, it shouldn’t take more than 10 minutes to fill it. If it takes more than 20 minutes to fill up an average-sized bathtub of 60 to 70 gallons, then you probably have a problem with the small tap diameter or slow water pressure.

If that is the case, then be sure to contact the plumber and see what the best solution for this problem is. If the faucet is the one making problems, it is not a big deal since it can be easily replaced with a new one. If low pressure is the problem, a plumber may need to examine it in more detail. Here is an example; a bathtub with a volume of 100 gallons needs around 20 minutes to fill up.

If you want to know more about bathtubs, be sure to read How a Bathtub Works?

Why do I Have Low Water Pressure in My Tub?

Fix Low water pressure in a bathtub

Sometimes it can be hard to figure out why you have low water pressure in your bathtub. However, you don’t need to worry about this, because you can always call a plumber and fix it. But the most common reasons why low water pressure occurs are the following:

1. Closed Valves

Each home has a water system with several valves that keep the system working correctly. Your water pressure may become low if any of them is closed or partially closed. Also, your local government can provide you with a map of the water valves in your home so that you can check them. However, you may check your water meter and the main shut-off valve and see if they are causing problems to your water system.

2. Clogged Faucet

Mineral deposits from water tend to start collecting in the holes of showerheads or inside the faucet’s head, causing blockages and mess with the water flow. You should use some effective cleaning solutions, such as vinegar or CLR, to prevent this from happening.

3. Faulty or Corroded Pipes

Sometimes you can have pipes that are even older than your home. If so, then they are probably causing the problem with your water system. Plumbing pipes that are older were made of metal, so they can easily corrode because of the rust and mineral deposits. If mineral deposits accumulate inside of the pipe, you will usually have problems with water flow in your home. If pipes are corroded, they can cause small leaks which can affect the water flow to your bathtub by making it slower.

4. The Water Mixing Valve is Worn Out

It is common for a mixing valve to become worn out or stuck over time which can cause temperature issues and problems with water pressure. A mixing valve controls how much cold and hot water goes into the faucet and the shower head (in bathrooms and kitchens) based on your choice. If you are having problems with a mixing valve, it will be easy to detect this problem and replace the valve. This should be performed by a licensed plumber too.

How to Get More Water Pressure in my Bathtub?

There are a few ways how you can increase the water pressure in your bathtub. Here are some of them:

Check With Water Supply  Company

If you checked your home and everything seems to be working well, you should contact your neighbors or your local water supply company to see if there is an issue. If your neighbors are having the same problem, then the problem is probably connected with the water supply in your area. If this is the case, then the water supply company needs to take care of it.

Clear Clogs In Your Pipes

Low water pressure can often happen because of clogs and blockages in your faucet or the pipes, so you may consider cleaning them regularly with vinegar, baking soda, or CLR to unclog them. If the pipes are really old and/or leaking, you will need to replace them.

Replace the Water Regulator

If you find out that your water regulator is causing problems, you can call a licensed plumber to fix this issue. It is usually located at the service line for your home or the meter. The costs of the replacement can vary depending on the accessibility of the new one but it is usually from $150 to $300 and sometimes even over.

Get a Water Booster Pump

By installing a water pressure booster pump, you can increase the water flow to your bathtub. You can buy them for $150 up to $600. They may increase your electricity bill, but they usually get the job done. They work by making pressure from your water source to move the water to the pipes from the water tank.

How Long Does it Take to Drain Water From a Bathtub?

A time that takes to drain water from a bathtub

If the drain system is working properly, it will take around 4-6 minutes to drain the average-sized bathtub. The diameter of the drain, as well as the bathtub’s volume and its filling, will affect the time it takes to drain water from it. The standard bathtub drain can accommodate easily 8.5 GPM (gallons per minute) with a diameter of 1 ½ inch. If you see that it takes a long time to drain water from your bathtub, it is usually a clog that is preventing the water flow from going faster.

If you have a hole in your bathtub and don’t know how to fix it, then read the following article: How To Fix a Hole In a Bathtub?

How Much Water Goes Through Bathtub Faucet Per Minute?

The bathtub faucet runs at 4 to 7 GPM (gallons per minute) on average. It may seem that taking a bath uses a lot of water but sometimes people use more water while showering. Usually, people use around 35 gallons of water when taking a bath and 40 gallons for a shower. So keep in mind that having a bathtub does not have to be more expensive than having a shower.

FAQ: People Also Ask

How Do you Fill a Bathtub Fast?

First, turn the water on. If you have a faucet with two valves, turn the cold water first and then add hot water until you are satisfied with the temperature. If your valve is mixing one, choose the most suitable temperature from the valve. It should take 5-10 minutes for the bathtub to fill.

How Much Does it Cost to Fill a Bathtub?

The average water cost is listed by every 1000 gallons in the US with a price of around $1.50. You are usually paying $0.01 for every gallon of water you use. An average-sized bathtub fits 40 gallons, so it will take $0.4 to fill it up.

How Many Gallons of Water does it take to Fill the Bathtub?

For an average bathtub, it takes around 60 gallons (227 liters) of water to fill it. The bathtubs that are smaller and ideal for children usually hold around 40 gallons (151 liters). It is an average of 35 gallons (132 liters) that is needed for taking a bath, according to industry standards.

How Long does it Take for a Hot Bath to Cool Down?

Around 100 minutes is needed for water to cool from 100 to 45 in a closed container. A bathtub is open, so it takes less for it to cool. It can be from 50 minutes to even 20.

Final Thoughts

There are a lot of bathtub models which have different designs and therefore it is hard to generalize and say an exact time it can take to fill up a bathtub. It can depend on a lot of factors. It usually takes around 5 to 10 minutes for an average-sized bathtub (that has 80 gallons in volume) to fill. If it is taking longer than 20 minutes, it can mean that you are having some issues with your pipes, water system, or a water provider in your area. We hope that this answers some of your questions about bathtubs!

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