Help & Advice

Garden Hose Flow Rate & Water Pressure

Everything you need to know about garden hose flow rate and water pressure for garden irrigation.

Learn everything you need to know about garden hose flow rate, including how it is calculated, and how to decipher the optimum flow rate for your irrigation and watering needs.

What is garden hose flow rate?
How much water does a hose put out per hour?
How do you calculate the garden hose flow rate?
Garden hose flow rate example
What's the difference between garden hose flow rate and hose water pressure?
How is garden hose water pressure calculated?
What does PSI stand for in water pressure?
What is a good water flow rate?
Why is garden hose flow rate important?
What factors affect garden hose flow rate?
How to increase garden hose water pressure
How to determine the best hose for your needs

What is garden hose flow rate?

Garden hose flow rate refers to the amount of water that passes through a hose within a certain amount of time. It's important to know your garden hose flow rate as this can help you best prepare and ensure that you're watering your plants correctly.

More specifically, garden hose flow rate refers to the amount of water passing from the tap spigot to the end of the hose, without any additional fittings attached.

Typically in the UK, a garden hose flow rate is measured in LPM. This stands for litres per minute. This can then give you the LPH, which is litres per hour. In the US, GPM and GPH are used (gallons per minute, gallons per hour).

How much water does a hose put out per hour?

You can work out how much water passes through your hose per hour by working out the flow rate, or LPM. This stands for litres per minute, which can then be converted into litres per hour by multiplying the LPM by 60. Read on to learn how to calculate the flow rate of your own garden hose.

How do you calculate the garden hose flow rate?

Determining the flow rate of your water source, such as a garden tap, is a simple exercise and requires nothing more than a bucket and a timer. When planning an irrigation system, it's essential to know the flow rate available from your water source to supply your irrigation system. If we try to release more water than we have available, your irrigation system will not perform properly. If we want to release more water than we have available, we know we must divide a system into multiple zones.

Calculating the flow rate in an open trough, such as a gutter or riverbed, is a bit more complicated, and calculating the flow rate of a liquid inside a closed pipe is even more complex. We will focus on calculating flow rate through an orifice in this article.

To measure the flow rate from your garden tap or something similar, all you need to do is time how long it takes to fill a bucket of a known size (the larger, the better) from the water source. We will use a 10-litre bucket to measure our flow rate in our example.

Place the bucket under the outlet of the water source to collect the water.
When you're ready, turn the tap on full and start the timer.
When the bucket is full, record the time it took to fill in seconds.
When we have this information, we can use the formula below to calculate our flow rate.

Garden hose flow rate example calculation

The following calculation is used to determine the flow rate in LPH:

The volume of container ÷ Time in seconds to fill = Litres per second

In our example, it took 30 seconds to fill a 10-litre bucket, so our calculation would look like this:

10 Litres ÷ 30 seconds = 0.333 litres per second

When our flow rate is measured as litres per second, we can convert this to show us litres per minute or litres per hour.

Litres per second x 60 seconds = litres per minute

Litres per second x 3600 seconds= litres per hour

With our example, our calculations would look like this:

0.333 litres per second x 60 seconds = 20 litres per minute

0.333 litres per second x 3600 seconds = 1'200 litres per hour.

What’s the difference between garden hose flow rate and hose water pressure?

People can sometimes confuse garden hose water pressure and garden hose flow rate, thinking they're the same thing. Whereas water pressure is a consistent measurement, presented in BAR in the UK and PSI in the US, the garden hose flow rate is calculated by adding the litre measurement and a measurement of time into the equation. This can help gardeners ensure they are not overwatering or underwatering their plants.

How is garden hose water pressure calculated?

The water pressure of your garden hose will be roughly the same as the water pressure for your home and equates to the speed at which the water enters your home from the water supply. You can use a pressure gauge to calculate the water pressure of your garden hose. The average pressure for home taps can be anything from 1 BAR to 5.5 BAR or 14.5 PSI to 80 PSI. One bar is the equivalent of 14.5 psi. Most commonly, in UK homes, bar pressure is used. One BAR of pressure is the equivalent of pushing water upwards of a distance of ten metres.

What does PSI stand for in water pressure?

PSI stands for pounds per square inch, and it is a measurement used to calculate water pressure, mainly in the US. UK homeowners will find pressure gauges and any existing records of their water pressure will be measured in BAR.

What is a good water flow rate?

A reasonable flow rate would be between 10 - 15 litres per minute or above 15 litres per minute for a truly effective flow rate.

If you are watering by hand using a garden hose, the higher the flow rate, the faster the water is delivered. If it's too fast, you risk overwatering. With a slower flow rate, you can be more controlled with how much water is supplied. If you have a high garden hose flow rate, we can control the flow rate using a hose nozzle with an integrated flow control.

For irrigation systems, the higher the flow rate, the better. The amount of water being released can be controlled with emitters and water timers. With a larger flow rate, larger irrigation systems can be built. If your garden hose flow rate is insufficient, it is possible to divide the irrigation system into multiple zones. This means only small portions of the system are activated at a time, so you can still expect good results, no matter your flow rate.

Why is garden hose flow rate important?

Knowing how much water is coming out of your garden hose is essential - too little or too much water can quickly lead to under or overwatering. You know how long to leave your hose on if you know the flow rate, meaning you can calculate ahead of time how long to apply water. This ensures you avoid wasting water or not using enough water. Effective flow rate allows for adequate watering, and the flow rate of your water supply can seriously impact the type of hose you buy and how much you water your plants.

What factors affect garden hose flow rate?

Below we discuss the key factors that can impact the flow rate of your garden hose.

Hose length

The length of your hose can seriously affect the garden hose flow rate, as the longer the hose, the less water pressure there will be. This is because as water travels down the hose, it can lose pressure and offer far less flow rate, commonly referred to as friction loss. If you need a longer hose, then it will be worth having a larger diameter. A larger diameter can decrease the velocity of the moving liquid as there is more space for the water to travel through and therefore better maintain pressure coming from the water source.

Does a longer garden hose decrease water pressure?

Yes, the longer the hose, the less water pressure there will be at the far end. This is because the water has further to travel, and more surface area to come into contact with. This friction over time results in a loss of energy and reduced viscosity, with less leftover pressure and a reduced flow rate by the time it leaves the far end of the hose.

What is the average length of a hose?

Average hose lengths are usually 25 metres long, and the flow rate can decrease by 75 percent when you quadruple the length of the hose. Shorter hoses will give you the best results for your plants. If you have a larger garden, this is an instance where a soaker hose or drip irrigation system may be a better option for you to ensure even coverage across your entire garden.

Does hose diameter affect water pressure?

A Larger diameter hose helps maintain the current water pressure as there is less resistance to the natural flow. A smaller diameter restricts the water flow, and in turn reduces the water pressure, but it increases the velocity (speed) the water travels.

The most common sizes are 1/2" in UK. 5/8" is commonly used in Europe and US. 3/4" is used by professional landscapers and horticulturalists.

Does a smaller diameter hose increase water pressure?

Water pressure cannot be increased once it reaches your home, however, the velocity of the water can be changed by restricting the size of an outlet. That is to say, the velocity of the water can be changed with a smaller hose diameter. It is possible to increase water pressure when it reaches your home, but it will require a pump, which can be costly depending on your needs.

Water is incompressible, so cannot ‘gain’ pressure by pushing it through a smaller diameter pipe. Pressure is linked to gravity, which is why water pressure is greater the deeper you go under the sea. It is not something that can be altered for your watering needs, which is why it is best to look into your options to see what can be done to get maximum results for your garden.

How to increase garden hose water pressure

Occasionally, you may find that the water pressure of your garden hose decreases. There could be several reasons why this occurs, so be sure to check all possibilities to find the source of the issue.

Look for any leaks

A very common reason for your water pressure to decrease is due to leaks in the hosepipe. If you notice a sudden drop in water pressure, check the hosepipe carefully for leaks. Leaks can be caused by kinks, twists or damage from the weather and can be easy to fix. If the hosepipe leak is irreparable, it may be worth replacing your garden hose. Other options include using a hosepipe connector, which can connect the pieces of the hosepipe together once the section with the leak has been removed. Otherwise, strong duct tape can do the trick as a short term solution.

Check that everything is connected properly

A reduction in garden hose water pressure can be caused by insecure connections, so ensure all your tap fittings and connectors are correctly connected.

Check for kinks or twists

Kinks and twists in your hose can also reduce the flow rate, as severe kinks or twists can interrupt the water flow.

Check for dirt and blockages

Dirt and unexpected blockages can impact the water pressure through the garden hose and cause unwanted blocks in the hosepipe. This can make it difficult for water to pass through undisturbed.

Check the pressure at the mains supply

Your water pressure may have reduced at the mains supply. You can check the water pressure by using a water pressure gauge which you can buy here.

Decrease the length of your hose

If your water pressure is significantly reduced while watering your garden, you may need to shorten your hose length. This can help ensure the water flows from the hose at a suitable pressure for your watering needs. This option is only suited to smaller gardens, but if you are looking for a simple way to increase garden hose water pressure, this method can do the trick.

Upgrade your hose to a larger diameter

As we've seen above, you can't increase water pressure without a mechanical intervention like a pump, but we can better maintain what water pressure we have by using a hosepipe with a larger diameter. That's why the pros always choose 3/4" hosepipe or in some cases, they go for a 1” hosepipe if they are using lengths of hose greater than 50 metres.

How to determine the best hose for your needs

Depending on your irrigation system and watering needs, there may be a garden hose more suitable to your needs compared to others. Factors that determine the best hosepipe for you include the foliage and plants you grow, the size of the hosepipe, the size of your garden, and how much sunlight and rain you can typically expect.

For more information on types of hosepipe, explore our help and advice section. You can read more about different types of irrigation systems below in our helpful guides.

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For more on all things irrigation, check out our help and advice page. Shop garden hoses and garden irrigation kits or get in touch with our team if you have any questions about your own watering needs.