What is water flow?

Flow is the volume of water that travels past a certain point per minute.

Water boards aim to supply water 9 litres per minute. So a 4.5 litre (1 gallon bucket) will fill in 30 seconds.

Poor flow rate often leads to poor water pressure. 

How does flow rate affect a shower?

Broadly speaking, the larger a shower head the more water flow is needed to maintain pressure. How much water your shower head needs should be supplied by the manufacturer. If the shower head required 10 litres per minute but your water system can only provide 9 litres per minute you’re not going to experience full power.

Water pump and shower pumps increase pressure but they can’t increase flow. This is the major advantage that a Proflow water booster has over a pump, is it makes more water avaialable to meet demand.

Pumps can push water into your shower header, but they can’t pull more water from the mains. If your mains supply is 9 litres per minute you’re never going to get more than 9 litres per minute out of your outlets.

Our boosters are essentially accumulator tanks that store a reserve of water for use when the demand is high.

Imagine you have 3 outlets in use:-

  • Shower: 8 litres per minute
  • Bathroom tap: 6 Litres per minute
  • Washing machine filling: 5 litres per minute

Total demand: 19 litres per minute.

If you only have 9 litres per minute coming into the property from source, your demand in the above case would outstrip supply by 10 litres per minute. i.e. the system needs another 10 litres per minute to maintain the correct pressure. The result is that the pressure and flow will drop for all of these outlets. The outlet that will experience the biggest drop in pressure will be the one that is the highest. This is normally an upstairs shower, because of the height of the shower head,  which is one of the worst places to loose water pressure.

The benefits of an Proflo water pressure booster accumulator tank

In the above example the system needs another 10 litres per minute. If we were to install a Proflo 200 litre accumulator tank you would have at least 20 minutes of additional water on standby. This would allow you to meet the demand of all the outlets and prevent that extra tap from affecting the shower pressure.

What is water pressure?

Water pressure is the force at which water travels through your pipes. Good water pressure is very important as it affects the flow of water from the tap or shower as well as the performance of your appliances.

The problem with low water pressure

Low pressure can reduce water flow to a trickle and it will take a long time to fill a kettle or a toilet cistern. Your showers lack “power” and baths take an age to fill up. More importantly, some boilers and showers rely on good water pressure and most will simply shut down if the pressure is too low.

How to measure water pressure

Water Pressure is measured in a unit called Bar. One bar equates to the amount of pressure required to push water to a height of 10 meters.

Given the diameter of your typical pipework, this amount of pressure would mean the flow of water is 9 litres per minute from a tap. So a one gallon (4.5 litre) bucket would take approximately 30 seconds to fill. This concept of flow is also important to understand when thinking about water pressure. It is very possible to have high pressure but your appliances still fail because the flow is low. This is why a Proflo water booster often performs better than a conventional pump. It provides a reserve tank of water that actually improves pressure by improving the flow. No pump can “generate” more water 

Click here for more information on water flow.

What controls your water pressure?

There are a number of factors that influence the pressure of the water, both inside and outside your property. Unlike a conventional pump, a Proflo water pressure booster can solve almost all of these problems. That is because it helps with the quantity of water available as well as the pressure. To better understand this read our page about water flow.

Get in touch for more details on how we can help.

Factors within your property that affect water pressure.

Height of source water source

If your water is coming from a tank in the loft, the difference between the height of this tank and the outlet; be it a tap or shower head, has a huge impact.  The higher the water source, the higher the water pressure.

Your pipework

Your existing pipework can also affect water pressure. Bottlenecks, where pipes narrow and some types of valve will reduce pressure. Gravity and friction also mean that long pipe runs, tight bends and vertical sections reduce pressure. Fitting a Proflo water pressure booster will resolve most of these types of issue. Contact us to find out more on how we can help.

The number of outlets in use

Water pressure that comes into your property is shared between every outlet. If a tap is on, there will be less pressure for other taps. This is why showers often suffer from low water pressure when another tap is turned on, or a washing machine is running.
Again, all of the issues can be removed or at least mitigated with the use of a Proflo water pressure booster.

Pipe leaks

If you have a pipe leak in within your property, it’s likely that you’ll notice fairly quickly. But in cases where it’s underground it could go unnoticed for some time. This is another potential cause of low water pressure. We can tell quickly if you have a leak using a range of pressure testing equipment.

Factors outside your property that affect water pressure.

The water pressure in your property is defined by the pressure of the mains supply. This should be around 1 bar, at the boundary. This is the point where the water leaves your water company’s pipework and uses your own. This point is normally just outside the property, where you find the stop valve.

Sometimes increasing your water pressure is as simple as ensuring that your stop valve is fully open.

You should not notice any difference in your water pressure after having a water meter installed.

Height of your property

The height of your property can also affect your water pressure. Properties at the top of a hill may receive lower pressure than properties which are at the bottom of the hill. The same principle can apply to flats that are a few storeys up.
How much water are your neighbours using?

You mains water source is shared with your neighbours.

If a number of neighbours run taps at the same time the increased demand will reduce pressure for others. This is why some homes have low pressure at certain times of day, typically in the morning when everyone is having a shower, or on a nice day when people are filling padding pools, watering gardens and washing cars.

Low mains pressure

Water companies are affected from the same causes of low water pressure as anyone else. Leaks, hills, height of water head can all affect your service.

Click here for details on how to test mains water pressure.

Is my water pressure sufficient to add an additional bathroom?

Whenever you’re looking to add additional outlets to an existing water system, it’s important to consider the impact this will have on the rest of the system. The first question should always be, is there enough water pressure to support the additional outlets?

Any additional outlets will put additional demand on your water supply and reduce pressure elsewhere.

In the case of an en-suite or additional bathroom, this could be significant and will put additional demand on your water supply. This in turn will have a direct effect on your water pressure and flow on all outlets. This could result it not only a weak shower, but problems with your boiler, washing machine or other appliances.

The extent of this drop in pressure will come down to how much pressure you have. As well as the number of outlets that you have open at any one time.

With Proflo water pressure booster, this additional demand can be catered for enabling you to add an additional bathroom without significant changes to other parts of your water system. Once installed, you will be able to run multiple outlets at once with a steady and balanced flow through each outlet.

Click here and get in touch for no obligation advice on water pressure problems

Why does my water pressure drop in my shower when someone flushes the toilet?

Your shower and toilet may share the same water source. i.e. your mains supply or water tank in the loft. The flow of water from this source will be divided between the number of open water outlets. If you’re in the shower and your toilet cistern starts to refill, because somebody has just flushed it, pressure to the shower will drop.

If this happens because you have a low water pressure the same is probably the case for any outlet is open. So the same shower will experience a drop in pressure when someone brushes their teeth or a dishwasher is on.

The solution is to improve the water pressure.

A Proflo water pressure booster is designed to remedy these types of situation by increasing both flow and water pressure. This will allowing you to have multiple outlets open at once without affecting flow. 

Click here and get in touch for no obligation advice on water pressure problems

How can I improve my water pressure?

There are many products which claim to improve your pressure. This is all well and good, but if the water flow is the problem these will offer little or no improvement. The performance of these products are also reliant on the water pressure that you are receiving from the water board. In short, in times of high demand they may not even operate. Pumps don’t operate if there is not enough water being supplied by the water board. Pumps can’t pull the water in!

Installing a Proflo water pressure booster will not only give you guaranteed results, as it is not reliant on the water pressure from your mains supply. As a result this system is future proof and will meet your needs.

Click here and get in touch for no obligation advice on water pressure problems

Why do I have poor hot water pressure?

If your cold water pressure is fine, but your hot water pressure if poor, there could be a number of reasons why.

Some of the reasons flagged in our section of water pressure problems could affect your hot water independently. For example, having a valve on your hot water pipes that is not fully open, long pipe runs or multiple sharp bends.

A more likely cause of low pressure of how water would be the source of the hot water itself.

If you have a combi boiler, your hot water flow is restricted at the boiler.

Cold water on the other hand has pressure from the height of the water tank, as is the case with gravity fed hot water, or it comes from the mains at around 1 bar. Both of these are likely to have higher water pressure than water from a combi boiler.

If you are suffering from hot water pressure problems you should consider a Proflo water pressure booster.


How can I measure my water pressure?

It is possible to purchase an adequate water pressure gauge for between £10-£20 from good DIY stores or plumbing merchants.

This simple device can be attached to an outside tap or water supply for a washing machine or dishwasher. Simply turn off the tap, screw on the water pressure tester and then open the tap again. This simple test will give you an accurate reading. Alternatively you should be able to find a local plumber who can do this for you.

More information on water pressure

Click here and get in touch for no obligation advice on water pressure problems

Can the water board turn up your water pressure?

Your water company is obliged, under the guaranteed standards scheme (GSS) to provide a maintain a minimum water pressure to your property. This is measured at the point that your own pipework starts, which should meet a 0.7 bar.

If this minimum pressure is not met you may be entitled to compensation.

There are however exceptions, where a drop in the water pressure wouldn't entitle you to compesation.

  1. a payment has already been made to the same customer in respect of the same financial year;
  2. it is impractical for the company to have identified the particular customer as being affected, and the customer has not made a claim within three months of the date of the latter occasion;
  3. industrial action by the company's employees makes it impracticable to maintain the pressure standard;
  4. the act or default of a person other than the company’s representative make it impracticable to maintain the pressure standard; or 
  5. the pressure falls below the minimum standard due to necessary works taking place or due to a drought 

Source: Ofwat The guaranteed standards scheme 

Click here to find out how to measure your water pressure.
Click here to find out more about how water pressure affects your property

Why is my water pressure low in the loft shower?

This is a very common problem, and it’s usually a result of the fact that the loft shower is higher up. The additional height that water needs to travel mean that water pressure is lost.
This can be the case no matter what type of hot water system that you use, but it’s a particular issue for gravity fed systems where the shower head is not much higher than your header tank.

To put this in perspective, your water pressure can decrease by up to 0.5 bar for every floor that it has to rise.

There are a number of solutions to this problem, but the most effective is a Proflo water pressure booster. This will increase both the flow and pressure of the water vastly improving your shower as well as the pressure elsewhere in the property.


Why is the water pressure in my shower low?

There are a range of factors that can affect the flow and pressure of water in your shower.

If your pressure is low it’s always worth checking the basics first. Make sure that your shower head isn't blocked by lime scale, so a good clean or replacement will fix that.

The shower head will also affect pressure if it is designed for a higher pressure system than you actually have. Put simply if the head has larger holes, or a larger diameter with lots of holes, you’ll need more water flowing through it to keep the pressure high.

Also check your pipework. Many installers will use small bore isolation valves along the pipes which will restrict your water flow. Full bore isolation valves are available and could help.


The most common cause however is simply low water pressure. To understand further the exact cause you need to know which kind of system your property has.

The 3 main types of hot water system are:-

  1. Gravity fed systems
  2. Mains fed combination boiler
  3. Mains fed hot water system (like a Megaflow)

Gravity fed systems

Older homes tend to have gravity fed systems and they are usually identified as having a cold water tank in the loft and a hot water cylinder in an airing cupboard.

What causes shower pressure problems in a gravity fed system?

In a gravity fed system your shower water pressure is governed by the difference in height between your header tank in the loft and shower head. This could be a as low as half a metre which only provides 0.05 bar of water pressure.

In these cases a Proflo water pressure booster would have a dramatic effect on the power of your shower by providing additional flow and pressure when you need it.

Mains fed combination (combi) boiler

These systems are easily identified as there is a boiler but no water tanks. Pressurised cold water is fed into your boiler and comes out the other side hot.

What causes low shower pressure when you’re using a combination boiler

Many of the smaller combination boilers provide between 6 to 10 litres of hot water per minute. This simply isn’t enough “flow” to create a powerful shower. One solution is to swap your combi boiler to one that is more powerful, to supply enough hot water for you needs.

A much more economical approach however is to fit a Proflow water pressure booster.

Mains fed hot water system (like a Megaflow)

Sometimes known as ‘sealed’, ‘pressurised’, ‘unvented’ or Megaflow hot water system.
In these system there is no cold water tank, but you fill find a large hot water cylinder.  The cold water supply comes from the mains, which is under pressure. This in turn pressurises the hot water.

What causes low water pressure in a mains fed hot water system?

It could be that the water pressure or flow is not sufficient to run the system efficiently. The main supply pipe may be undersized or there may be restrictions on the pipe work, which reduces your water flow. 

Again, our Proflo water pressure booster will fix these issues.