How Long Does It Take To Fill Up a Bathtub? Answered.

The idea of jumping right into a warm water-filled bathtub after a long day is pretty tempting. But as you have to wait until the tub fills with its maximum capacity, you may wonder – how long does it take to fill up a bathtub?

Usually, an average bathtub takes around 10-15 minutes to fill at its max capacity. But this may depend on many factors. For instance, you have to take account of your bathtub’s volume, water flow rate, water pressure, size of the pipes, etc., to know the exact filling time. 

In this article, we’ll explain how these factors affect the time and give solutions if your bathtub takes too long to fill. 

How Long Does It Take To Fill Up a Bathtub on Average?

Most bathtubs can hold water of about 40-60 gallons. However, there are large bathtubs that can even contain 80-100 gallons of water. Also, we do not fill the bathtub at its max capacity before taking a bath.

Generally, a bathtub takes 5-15 minutes on average to fill up. Let’s consider that your bathtub faucet, pipes, or water pressure regulator is functioning correctly, and the water flow rate is 4-7 gallons per minute. So we can expect- 

Bathtub TypeBathtub CapacityAverage Filling Time
Small40 Gallons (or, 151 Liters)6.5 minutes
Medium60 Gallons (or, 227 Liters)10 minutes
Large80 Gallons (or, 302 liters)13 minutes

However, it may not be accurate if your water pressure or water flow rate is less than average. 

Usually, it takes about 30 gallons of water for a single person’s bath. So despite the capacity of the tub, if you want to fill 30 gallons with a water flow rate of 4-7 gpm, it’ll take only 5 minutes to fill the bathtub.

Moreover, there are large tubs too that can contain around 100 gallons. For the same water flow rate, it’ll take about 17 minutes to fill those bigger tubs. 

Factors That Vary the Time To Fill Up a Bathtub

What we discussed was for the average case. But some factors may vary the time to fill up a bathtub. So let’s understand these factors.

Bathtub’s Volume

A bathtub’s volume is its capacity to hold water. It’s often measured with m3 and then converted to liters or gallons. 

It’s a general idea that the bigger the tub, the more time it’ll take to fill it up. Also, there are bathtubs of different shapes and designs. These unique designs may make the volume of the tub slightly bigger or smaller. 

Water Flow Rate

Water flow rate means how much water comes from the bathtub faucet per minute. Generally, our bathtub faucets release water at a 4-7 gallons per minute rate. It’s not a fixed value and can be different from house to house. 

Many things can slow down this flow rate. For instance, if your faucet is faulty or clogged, less water will come from it. Therefore, it’ll take more time to fill your bathtub. 

Water Pressure

Water pressure is another important factor that can affect your bathtub filling time. It means at what force the water is pushed through the pipes. 

In our houses, the water pressure is set to 45 to 60 PSI (Pounds per square inch). If it’s less, the water flows out rather slowly. And it ultimately affects the water flow rate from the faucet. 

How Can You Calculate Your Bathtub’s Filling Time?

To calculate your bathtub’s filling time, you need to know to parameters- 

  • Your bathtub’s volume/water capacity
  • The water flow rate of your bathtub’s faucet

So if you don’t know your bathtub’s volume, you can measure it by yourself. For this, take a measurement tape and measure the tub’s length, width, and depth in meters.

Once you know these three values, multiply them to get the volume. It’ll be in m3, so to make it in liters, multiply by 1000. 

Bathtub’s Volume = (Length x Width x Depth) x 1000 liters 

If you want to know the volume in gallons, multiply the m3 volume by 264.2 gallons instead of 1000. 

To calculate the water flow rate, you need a bottle or bucket of a known volume. For example, take a 1liter bottle or a bucket of 1 gallon and then put it under the tap of the bathtub. 

Let the water flow, and start the timer. Now, keep counting until the bucket fills full. Stop the timer and measure the time it took.  

To find the bathtub filling time, multiply this time by the volume of the bathtub. But remember, the volume should be in the same units as the bucket/bottle. 

So bathtub’s filling time = (1 liter bottle filling time) x (bathtubs volume in liters) 

Or, (1-gallon bucket filling time) x (bathtub’s volume in gallons) 

Why Does Your Bathtub Take Longer To Fill?

If your bathtub takes longer to fill, for instance, 20-30 minutes or even more, there might be several reasons. It can happen if your water pressure on the pipes is less than average or water from the faucet flows slowly. 

Whatever the reason, you have to troubleshoot it before considering solving it. 

Here are some common reasons why your bathtub takes longer to fill- 

Clogged Faucet or Valve

The faucet of the bathtub allows water to flow in the tub. It is supposed to function smoothly. However, the faucet can get clogged due to the accumulation of mineral deposits and may not work properly.

Moreover, there are many valves all around the water system of your house. These valves help to regulate water pressure. If somehow any of these valves are trapped or clogged, water may flow with less pressure.

So check for the blockage in your faucet and valves. If you find any, you need to clean it or replace the part with a new one. 

Clogged or Damaged Pipes

Another reason your water flow rate is less is you have faulty or clogged pipes. If the pipes are old enough, they can get damaged by rust and mineral deposits over the years.

Furthermore, there can be leaks in the pipes too. And if your bathtub pipe has leaks, water will flow through them and less water will conquer its way to the tub. 

So inspect if your water supply pipes are damaged, leaked, or clogged. You may need to call an expert for this. 

Low Water Pressure

The average water pressure in our house is 45 to 60 PSI. However, due to many problems, this level can be lower. 

If your water system has low water pressure, the water flow rate will also be less, so it’ll take more time to fill your tub. 

There’s a water pressure regulator in your house that regulates water pressure and keeps it to an almost desired value. However, this regulator can get faulty over time. And if that happens, your water pressure will be extremely low or high. 

Problems in Hot Water Supply

Many people face that it takes more time to fill their bathtub when they turn on the hot water. It can happen for two reasons. First, the water mixing valve is not working correctly, and second, your heater has some issues. 

It’s easy to troubleshoot this problem as it only appears when you use hot water. So, take action if you notice your mixing valve is damaged and needs a replacement.

Also, check if your water heater is working correctly or not. You can call an expert, and they’ll help you replace the component if you need it.  

The Final Thought

It takes only 10-15 minutes to fill up a bathtub. So, you can turn on the faucet, wait for that short time and just jump into the water to remove your stress! 

However, if it takes longer, you can call a plumber to check for the issues with your water pressure. Finally, we hope that you get that calming bath that you deserve! 

Some FAQs

How Much Water Does It Take To Fill a Bathtub?

People, on average, use 30 gallons (113 liters) of water in their bathtubs for regular baths. However, there are many bathtubs with different capacities. For instance, it may take 40 gallons, 60 gallons, 80 gallons, or even 100 gallons of water to fill larger bathtubs. 

What Is the Cost of Filling a Bathtub?

The cost of filling a bathtub depends on the average price of water in gallons. For instance, the US charges $1.5 to $2 per one thousand gallons. So, for every 40 gallons of water in a bathtub, they have to pay 8 cents. 

How Long Does It Take To Fill a Hot Tub?

A hot tub is larger than regular bathtubs and can hold about 300-400 gallons of water. So, on average, a hot tub takes 90-120 minutes to fill. However, it depends on how big the tub is and at what rate the water flows through the pipe and faucet. 

How Long Does It Take To Drain a Bathtub?

It takes 2-5 minutes to drain water from your bathtub completely. It depends on the size of your tub and how perfectly your draining system is functioning. If your draining system is not clogged, it can drain about 8.5 gallons of water per minute from your bathtub.

How Much Water Should I Fill My Bathtub?

It’s better not to fill your bathtub at its maximum capacity. Instead, you should fill your bathtub around 65%-70% or 2/3 of its volume. It’s because when you sit in your tub, your body takes up some space of the tub. So if you fill it whole, the water will spill when you’ll get into the tub and create a mess in your bathroom.