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Witten by Bernard Morgan (Engineer) & Adam Apperley (Marketing). Published: February 6, 2024. Updated: February 16, 2024

Water Pressure vs Water Flow Rate

Water pressure and water flow are key factors of your plumbing system. But what sets them apart? And how do they work together to keep your plumbing running?

Whether you have a combi boiler or a system boiler, this is worth knowing. Below we dive into the details, guided by the expertise of Boilerhut’s engineering team.

Water pressure vs. water flow

Water pressure refers to the force exerted on water to propel it through your pipes and plumbing system. Factors like altitude and gravity influence it. For instance, your upstairs bathroom will have less pressure than your ground-floor kitchen.

On the other hand, water flow represents the volume of water passing through your pipes at any given time. It’s determined by the width of the pipes and the pressure surging through them.

Understanding their role

In simple terms, water flow measures how much water exits your pipes, while water pressure determines how forcefully it does so. Friction can affect both pressure and flow, especially if sediment builds up inside your pipes, causing a decrease in both.

Wider pipes generally allow for better water flow. Closed valves, clogs, leaks, and sediment buildup can disrupt pressure and flow.

Measure your water flow rate

  • Grab a bucket, preferably 5 litres in size
  • Use a stopwatch (on your smartphone)
  • Place the bucket under an outside tap or kitchen sink tap
  • Turn the tap on and start the stopwatch
  • Turn the stopwatch off once the bucket is full
  • Calculate the flow rate: Divide the number of litres by the time in minutes (remembering that 30 seconds is half or 0.5 of a minute).

Example 1: if you filled your 5 litre bucket in 30 seconds, 5 litres / 0.5 minutes (half of a minute) = 10 litres/minute.

Example 2: if you filled your 5 litre bucket in 15 seconds, 5 litres / 0.25 minutes (quarter of a minute) = 20 litres/minute.

Your results: Less than 10 litres per minute indicates low water pressure. Between 10 and 15 litres per minute is acceptable but can be improved. A flow rate above 15 litres per minute is considered good.


In conclusion, water pressure and water flow rate are essential components of your plumbing system. Understanding how they function and recognising common issues can help you maintain optimal performance and address problems promptly. Trust Boilerhut’s plumbing experts to keep your plumbing system in top shape.

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