How to increase or boost water pressure

Posted 7th January 2019

Dreaming of a powerful shower? Is your bath taking aeons to fill up?  Then you need to know how to increase water pressure with a booster pump set-up.

The flow rate at which water is delivered depends on two factors:

• Water pressure, which is governed by how high your water reservoir, tower or pump station is compared to your property.  Other factors like pressure regulators upstream of your property will reduce the effective water pressure.  In simple terms, the pressure is measured by the head (height) of water. In a gravity fed system, 1 bar of pressure will be felt if your water tank is 10 metres above your tap, 2 bar is 20 metres, 3 bar is 30 metres etc.
• Pipe diameter; the diameter of the supply pipe between the reservoir and your property will affect flow rate and water quantity available at your tap.  The water main feeds other properties, so in peak times you may have a drop in your flow of water when it’s most needed.  Older properties may have a 1/2″ pipe, newer housing will have a 1″ water main which will help.  Cities with lots of development may not have the water system infrastructure upgrades that can supply all new dwellings, and new demand.

There are lots of reasons for increasing your water pressure, but ultimately it’s to improve quality of life.  With a small investment in the correct hardware, it’s simple to achieve.

Can I install a booster pump directly in the main water pipe? 

You might think a simple solution would be to install a pump in the main water pipe, thus increasing the water pressure.  For several reasons, this is not a viable solution.  Pumps are great at pushing water, but not designed to pull it. Pumping directly from the water main will make the pump pull from the water main (which may already be limited).  This will drag down the pump capability and wear it out faster, without much improvement in flow rate.  Due to the water company and local bylaw regulations, pumps capable of delivering above 12 litres/minute are not to be installed in the water main.

The solution

It’s not difficult to achieve a good flow rate for the whole house, but you need two key components:

• A water break tank with a float valve
• A water booster pump with an automatic control system.

Install a break tank to create higher than mains pressure

The water break tank is supplied from the cold water supply and fills up with a float valve.  The storage tank should be sized to allow for peak demand. Otherwise, when you want to use the water there won’t be enough capacity to fill your needs.  When there is space in the break tank the water main refills it.  Then it turns off when it’s full, ready for the next demand.  Since the same amount of water will be used thanks to the tank your water meter shouldn’t change too much.

Typical sizes of break tank will depend on the property size and number of occupants.

A typical 1 or 2 bedroom flat with one bathroom – 125L to 150L water tank

A 3 to 4 bedroom house – a 200L to 250L water tank will work well.

If you have multiple bathrooms like a guest house or bed and breakfast, then a bigger tank will be required depending on the expected peak demand.

It’s best to install the break tank at ground level where the mains water flow will be at its best.  The kitchen, utility room and as near to the incoming water main as possible are the best places to install one.

Combining a water booster pump with the break tank

The water booster pump should be installed next to the break tank, so it’s pushing water to the rest of the dwelling’s water main pipe.  A good quality pump that is quiet in operation is a must.

A system of pressure and/or flow sensors control the pump, combined into a compact unit, plumbed into the pump outlet port. This unit will automatically control the pump, switching the pump on when the pressure drops and switching the pump off when there is no demand. There are two main types of pump controller for booster water pressure.

Pressure switch: This simply works by switching on and off at preset pressures. As an example, the switch could be set to turn on at a low of 1.5 bar and turn off at 2.8 bar. The “off” pressure setting needs to be below the maximum pump pressure. To help smooth out pressure spikes and hammering you use this type of pressure switch with an expansion vessel.  When you close a tap quickly or the washing machine closes a valve it regulates the pressure.

Flow Controller:  This works in a similar way to the pressure switch, but has the advantage of not being limited to the pressure switch setting and can use the full pressure of the pump as the “off” switching is achieved by a flow sensor allowing the full performance of the pump.  This style of flow controller has the advantage of a ‘run-dry protection’ system.  If the controller detects no flow the pump will switch off, which protects the pump. Most flow controllers have an automatic restart feature, so if the pump runs dry and switches off, it will restart after a set period of time.

Boosting water in hotels, larger homes or non-domestic properties

Hotels, guest houses and larger properties may have the same low flow rate issues, usually compounded by higher demands at peak times. Typically a hotel where multiple guests would like showers at 7:30 AM or 6 PM.  The solution is similar but the equipment is slightly different. The break tank will need to be larger, so outside the main building may be the best place for installation.  The pump system will require a high level of control with the use of variable speed pump controllers and pumps, to keep up with the varying flow rates and demand cycles.  Firstly a consultant will assess the requirements and measure the mains water flow.  Their assessment leads to designing a system to maintain the desired flow rate and pressure at all times of the demand cycle.

Showers and how they work

We tend to suffer most from low water pressure when our shower head produces a measly sprinkle.  Shower pumps can alleviate this issue specifically and are cheaper than you might think.  Combi boilers can be disappointing in a larger house so getting that little extra boost might be what you need.  Otherwise, a good quality electric shower might be the answer as they take the generally higher pressure cold water and heat it actively.

Existing plumbing?

There are a few things you need to be aware of if you intend to boost your water pressure.

If the property’s hot water cylinder doesn’t vent, hot water tank and heating system run from mains water plumbing (i.e. no water tank in the loft), boosting your water pressure will increase water flow to both the cold and hot water supply equally.

If you have a cold water tank in the loft, a header tank, then the above system will not boost the flow.  The height of your existing header tank determines this, for instance.  You can pump from your cold water tank in the loft, but you will need to make sure you know how the heating system works.

We always recommend a qualified plumber or heating engineer to carry out any installation of a booster system.  All installations must comply with water bylaws and regulation.

OFWAT is a great source of information.  If you require further assistance, contact us, using the form below, or call on 01722 714514.