WaterBoost- Slimline EXT
WaterBoost WB-EXT Slimline 150 Mini3 Variable Speed 2501210
- Established 1975
- Trusted by thousands of customers
The WaterBoost WB-EXT Slimline 150 Mini3 is a compact, variable-speed water boosting system combining a 150-litre WRAS-approved slimline tank (600mm dia × 650mm high) with the DAB Esybox Mini3 external pump. Delivering 50 l/min at 3 bar, it brings variable speed performance, WiFi, and voice control to a highly practical low-profile format — ideal for 1–2 bedroom homes where space is restricted.
The Esybox Mini3 sits alongside the tank rather than inside it, providing easy access for servicing and maintenance. The tank connects directly to the mains via the pre-fitted ¾” ball float valve, and the system arrives fully pre-built. At just 650mm tall, it fits under kitchen units, in low cupboards, and in spaces where taller systems cannot.
Supplied with union connections, ¾” ball float valve, 600mm hose, and By-law 30 kit. The tank carries a 5-year warranty and the DAB Esybox Mini3 a 3-year warranty. Please contact us for delivery timescales.
WRAS tank & pump
Only 650mm tall
Variable speed
Direct mains
5yr tank warranty
More about this product
The WaterBoost WB-EXT Slimline 150 Mini3 brings the performance of the DAB Esybox Mini3 to a compact, low-profile tank system. The 150-litre WRAS-approved tank sits at just 650mm tall — fitting under kitchen units, in low cupboards, and in spaces where taller systems cannot — while the external Mini3 delivers 50 l/min at 3 bar with variable speed efficiency. Designed for 1–2 bedroom homes where space is tight but performance matters.
Unlike internal-pump systems, the Mini3 sits neatly alongside the tank. This makes it easy to access for servicing, and means the pump benefits from the full Esybox Mini3 feature set — WiFi via the DConnect app, Google Home and Alexa voice control, and variable speed adjustment to match demand. The mains connects directly via the pre-fitted ¾” ball float valve. Fully pre-built, no site assembly required.
5-year tank warranty and 3-year DAB pump warranty. Please contact us for delivery timescales.
Three compact boosting systems for smaller properties. The WB-EXT Mini3 has more storage and higher flow than the Compact Fixed, and adds WiFi and variable speed. The Powertank COMPACT units are rated to Fluid Category 5 and have a washing-machine-sized form factor that hides behind a cupboard door.
WB-EXT Slimline 150 Mini3 — the best overall choice for most potable water boosting. More storage (150L vs 125L), higher flow than the Compact Fixed (50 vs 40 l/min), variable speed, WiFi and voice control, and named 5yr tank and 3yr pump warranties. Excellent for 1–2 bedroom homes needing low-profile installation with smart features.
Powertank COMPACT 125 Fixed — choose if Fluid Category 5 compliance is required, or if the square washing-machine form factor suits your installation space better than a cylinder + external pump. 40 l/min.
Powertank COMPACT 125 Variable — highest flow in this group at 65 l/min with Fluid Category 5 compliance. Choose if Cat 5 and 65 l/min are both specifically required.
How is it delivered?
What does “EXT” mean — why is the pump external?
How does the mains connection work?
Is 150L enough storage for my home?
How does the WiFi work?
What warranties are included?
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-EXT Slimline 150 Mini3 Variable Speed 2501210. 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.