WaterBoost- Slimline EXT
WaterBoost WB-EXT Slimline 300 Mini3 Variable Speed 2502210
- Established 1975
- Trusted by thousands of customers
The WaterBoost WB-EXT Slimline 300 Mini3 is a variable-speed water boosting system combining a 300-litre WRAS-approved slimline tank (600mm dia × 1200mm high) with the DAB Esybox Mini3 external variable speed pump. It delivers a reliable 50 l/min at 3 bar with WiFi, DConnect app, and Google Home and Alexa voice control — a capable variable-speed option in the slimline range for 3–4 bedroom homes.
The Esybox Mini3 sits alongside the tank rather than inside it, providing easy access for servicing and maintenance. At 600mm diameter the tank fits through a standard doorway and can be installed under stairs, in a garage, or in a utility room. The mains connects directly via the pre-fitted ¾” ball float valve. Supplied fully pre-built with no site assembly required.
Includes 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
Variable speed
Fits through doorway
Pre-assembled
5yr tank warranty
More about this product
The WaterBoost WB-EXT Slimline 300 Mini3 brings variable-speed performance, WiFi, and voice control to an upright slimline format that fits through a standard doorway. A 300-litre WRAS-approved slimline tank (600mm dia × 1200mm high) pairs with the DAB Esybox Mini3 external variable speed pump, delivering 50 l/min at 3 bar. Designed for 3–4 bedroom homes with poor pressure or restricted mains flow.
The Esybox Mini3 sits alongside the tank — not inside it — keeping the pump fully accessible for servicing or replacement at any time, and running at a whisper-quiet 45 dB(A). The mains connects directly via the pre-fitted ¾” ball float valve. Supplied fully pre-built — no site assembly needed. The 600mm diameter tank fits through a standard doorway for installation under stairs, in a garage, or utility room.
Includes union connections, ¾” ball float valve, 600mm connection hose, and By-law 30 kit. 5-year tank warranty and 3-year DAB pump warranty. Please contact us for delivery timescales.
Three upright slimline systems in the 200–350L range. The WB-EXT 300 Mini3 offers the highest flow and adds variable speed and WiFi. The Powertank options offer Fluid Category 4 compliance for those who specifically require it.
WB-EXT 300 Mini3 — the standout all-round choice. More storage than the 200 (300L vs 200L), higher flow (50 vs 40 l/min), 5.5 bar max, WiFi and voice control, variable speed, and named 5yr tank and 3yr pump warranties. The right choice for potable water boosting in 3–4 bedroom homes.
Powertank SLIMLINE 200 Fixed — choose only if Fluid Category 4 compliance is a firm requirement. 200L, 40 l/min.
Powertank SLIMLINE 350 Fixed — choose for Fluid Category 4 with more storage (350L). Still 40 l/min, fixed speed, no WiFi. Choose only if Cat 4 is a specific requirement.
How is it delivered?
Why is the pump external rather than inside the tank?
How does the mains connection work?
Is there a 500L version in the same EXT format?
How does the WiFi control 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 300 Mini3 Variable Speed 2502210. 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.