Water Pressure vs Flow Rate: What's the Difference
Pressure and flow rate are often used interchangeably but they measure different things, and confusing the two leads to the wrong fix when a shower or tap disappoints..
Pressure and flow rate are often used interchangeably but they measure different things, and confusing the two leads to the wrong fix when a shower or tap disappoints.
What pressure actually measures
Pressure is the force pushing water through the pipe, typically measured in bar, and it's what gets water up to a top-floor bathroom in the first place.
What flow rate actually measures
Flow rate is the volume of water delivered over time, measured in litres per minute, and it's what determines how quickly a bath fills or how strong a shower feels.
Why you can have one without the other
A property can have good pressure but poor flow if the supply pipe is narrow or restricted, which is why both need checking separately when diagnosing a weak shower.
How to tell which one is the issue
- Check flow rate by timing how long a bucket takes to fill from a tap
- Check pressure with a gauge at an outlet
- Poor flow with good pressure often points to pipe restriction
- Poor pressure usually affects the whole property, not just one outlet
Who does the work
- Gas Safe registered engineers — registration 554328
- Worcester Bosch accredited installer
- John The Plumb Ltd, company registration 10026483
Get your pressure and flow diagnosed
Describe which outlets are affected and we'll test both pressure and flow rate to find the actual cause.
Questions we get asked
Which one matters more for a shower?
Both matter, but flow rate is often the more noticeable factor for how strong a shower feels day to day.
Can low flow rate be fixed without digging up pipework?
Sometimes a restriction is at a stopcock or filter rather than the supply pipe itself, which is worth checking before assuming major work is needed.
Does the water company control my pressure and flow?
The mains supply sets a baseline, but internal pipework, valves and fittings within the property also significantly affect what reaches your taps.