WaterBoost Compact
WaterBoost WB-Compact 3.0 low mains pressure booster
- Established 1975
- Trusted by thousands of customers
The WaterBoost WB-Compact 3.0 is a compact variable speed inline mains pressure booster that connects directly to the incoming mains supply — no tank, no break tank, no overflow. It reacts automatically to low mains pressure, boosting supply to the entire property to up to 3.0 bar at up to 12 l/min. Ideal for combi-boiler homes, unvented cylinders, electric showers, and mixer showers.
Suitable for heat pump systems where mains flow is adequate. Raises pressure to an unvented hot water cylinder when the supply has the flow but not the pressure. If flow is short, choose a stored-water WaterBoost system.
The variable speed inverter motor adjusts output to match demand, delivering smooth and stable pressure at a measured 40 dB(A) — quieter than a normal conversation. Built-in WiFi connects to the DConnect app for remote monitoring and control, and supports voice commands via Google Home and Amazon Alexa. Available in straight ¾” BSP and right-angle ¾” BSP connections. A full-bore bypass can be fitted for uninterrupted supply during maintenance.
WRAS compliant. 3-year warranty. For higher maximum pressure, see the WB-Compact 4.5. For a storage-based solution, see the ATX-200.
Variable speed
Direct mains — no tank
Straight & right-angle BSP
Full-bore bypass
WRAS compliant
More about this product
The WaterBoost WB-Compact 3.0 is a compact variable speed inline mains pressure booster. It connects directly to your incoming cold water mains supply and reacts automatically whenever mains pressure falls below the pre-set threshold — boosting flow and pressure throughout the property without any break tank, overflow, or additional pipework beyond the two inline connections.
Capable of boosting incoming mains supply to up to 3.0 bar at a flow rate of up to 12 l/min, it is ideal for combi-boiler homes, unvented hot water cylinders, electric showers, and mixer showers. The inverter-driven variable speed motor adjusts output to match the actual demand in real time — maintaining smooth, stable pressure and keeping noise to a measured 40 dB(A).
Built-in WiFi connects to the DConnect app for remote monitoring and control, and supports voice commands via Google Home and Amazon Alexa. Available with straight and right-angle ¾” BSP connections to suit the installation. A full-bore bypass can be installed for uninterrupted supply during maintenance.
What is the difference between an inline mains booster and an accumulator system?
An inline mains booster like the WB-Compact 3.0 sits directly in the pipe and boosts whatever flow rate the mains supply delivers at that moment. It increases pressure but cannot increase flow beyond what the mains provides. An accumulator booster system (such as the ATX-200) stores a volume of mains water under pressure and can deliver flow rates significantly higher than the mains alone could supply — at the cost of a larger unit and higher price. If your mains pressure is the problem, an inline booster usually solves it. If your mains flow rate is also restricted, an accumulator system is likely a better fit.
Does the WB-Compact 3.0 boost both hot and cold water?
Yes. When installed on the incoming mains supply, the WB-Compact 3.0 boosts both hot and cold water throughout the property — including to combi-boilers and unvented cylinders. It should be installed by a qualified plumber in compliance with Water Regulations.
What is the difference between WRAS compliant and WRAS approved?
WRAS compliant means the product meets the requirements of the Water Supply (Water Fittings) Regulations 1999 and is suitable for connection to the mains supply. WRAS approved means the product has additionally been independently tested and certified by the Water Regulations Advisory Scheme and appears on the WRAS product approval list. Both indicate the product is legally fit for mains connection, though WRAS approval provides an additional layer of independent verification.
What does variable speed mean and why does it matter?
A variable speed (inverter-controlled) pump adjusts its motor speed to match the actual demand at the tap or shower at any given moment. A fixed-speed pump runs at full power whenever it activates regardless of demand, which causes pressure surges, higher energy use, and more noise. Variable speed delivers smoother pressure, lower running costs, and quieter operation — particularly noticeable when only one outlet is open rather than several.
Is a higher pressure version available?
Yes. The WB-Compact 4.5 boosts up to 4.5 bar, suitable for properties requiring higher pressure or where the mains supply can support a higher boost level. For properties where flow rate is also the issue (rather than pressure alone), the ATX accumulator booster range may be a better fit. Contact us if you are unsure which product suits your situation.
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Standard delivery:
Standard delivery is free on most orders. Some items may incur a delivery charge depending on weight, size or value. Any applicable charge will be displayed at checkout.
Deliveries will typically be made between 7am and 6pm, Monday to Friday (excluding public holidays).
Next day delivery:
Next working day delivery is available for a £16.50 + VAT delivery charge.
Orders must be placed before 12 noon to qualify for next working day delivery. Orders placed after 12 noon on Thursday but before noon on Friday will be delivered the following Monday. Orders placed after 12 noon on Friday will be delivered on Tuesday.
Pallet/Large/Difficult items:
Some large, heavy or difficult to transport items may incur an additional delivery charge. Please contact us for a delivery quote before ordering.
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Frequently Asked Questions
Quick answers to common questions about the WaterBoost WB-Compact 3.0 low mains pressure booster. For technical specifications, see the product details above; for sizing or installation advice, contact our team. If you have any other questions, we're happy to help.
What is a mains pressure boosting system?
A mains pressure boosting system increases the pressure and flow of water from the incoming mains supply into a property. It typically combines a pump and a storage or expansion tank, drawing water from the mains and delivering it to taps, showers and appliances at a stronger, more consistent pressure. They are used where the incoming mains is too weak to serve modern outlets reliably.
When do I need a mains booster pump?
You normally need a mains booster if static mains pressure is below 1.5 to 2 bar, if showers run weakly when other taps are open, or if combi boilers struggle to deliver hot water. Anglian Pumping recommends checking static pressure at the stop tap before specifying a system, then choosing a model rated for the number of bathrooms and outlets in the property.
What size mains booster do I need for my home?
Sizing depends on the number of bathrooms, the type of fittings and the static mains pressure. As a guide, a 1 to 2 bathroom property with combi boiler or single shower often needs 1.6 to 3 bar boost. A 2 to 3 bathroom property typically needs 3 to 4.5 bar with an integral break tank. Larger homes need a tank-and-pump system such as the DAB Esybox with Esytank or a Powertank set.
What is a water booster pump?
A water booster pump increases the pressure of an existing water supply to give stronger flow at taps, showers and appliances. It can be a small inline pump fitted to the incoming mains, or a larger pump and tank set that draws from a break tank to feed the whole house. Boosters do not create water – they raise the pressure of the water already coming in.
What is the difference between an inline booster and a tank-and-pump booster?
An inline booster connects straight onto the incoming mains and is limited to 12 litres per minute under UK water regulations – examples include the Salamander HomeBoost and WaterBoost WB-Compact. A tank-and-pump booster, such as the Grundfos Home Booster or DAB Esybox with Esytank, draws from a break tank and can deliver much higher flow rates for larger homes with multiple bathrooms.
What is a variable speed booster pump?
A variable speed booster uses an inverter to adjust pump speed in real time to match demand. It maintains constant pressure as outlets open and close, runs more quietly than a fixed-speed pump and typically saves up to 50 per cent of the energy a fixed-speed equivalent would use. The DAB Esybox, DAB Esybox Mini 3 and Grundfos Scala2 are common variable speed examples.