WaterBoost – Advant Slim
WaterBoost WB – Advant 400 slim Esybox 2604B110TP
- Established 1975
- Trusted by thousands of customers
The WaterBoost WB-Advant Slim 400 Esybox TP is the narrowest tank in the entire WaterBoost range with the higher-flow DAB Esybox pump mounted directly on top of the tank — serious performance in installations with severely restricted access, on nothing more than the tank’s own footprint. A 400-litre WRAS-approved UK-manufactured Advant slimline tank (400mm W × 1050mm L × 1253mm H) pairs with the DAB Esybox variable speed pump, delivering 80 l/min at 3 bar and up to 6.5 bar maximum — with WiFi, DConnect app, H2D technology, Google Home and Alexa voice control.
At just 400mm wide, the vertical slimline tank passes through a standard doorway with a generous 362mm to spare — opening up loft hatches, tight cellars and utility spaces that no other tank can reach. With the Esybox top-mounted on the tank, the system takes up no floor space beside the tank at all, while the pump stays at working height for servicing and runs at an exceptionally quiet 43 dB(A). The tank connects directly to the mains via the pre-fitted ¾” ball float valve, with 1.5” outlet. Pump platform and all interconnecting pipework supplied — no site assembly required.
The UK-manufactured tank carries an outstanding 10-year warranty and the DAB Esybox a 3-year warranty. Delivery is typically 1–2 working days.
362mm doorway clearance
WiFi · H2D · Google · Alexa
WRAS tank & pump
6.5 bar max
43 dB(A) — ultra quiet
By-law 30 kit included
Type AB Airgap available
1–2 day delivery
More about this product
The WaterBoost WB-Advant Slim 400 Esybox is the narrowest tank in the entire WaterBoost range with the higher-flow DAB Esybox pump mounted directly on top — combining a 400-litre WRAS-approved slimline storage tank with the DAB Esybox variable speed pump in a single self-contained unit. It is engineered for smaller-to-medium domestic properties, retrofits and installations with severely restricted access — where you still need serious 80 l/min performance and have no floor space to spare.
At just 400mm wide, the vertical slimline tank clears a standard 762mm internal doorway with a huge 362mm to spare — enough clearance for the tightest hallway turns, loft hatches, cellar staircases and utility routes that no other tank in the range can navigate. Capable of delivering 80 l/min at 3 bar and up to 6.5 bar maximum, the Esybox continuously adjusts its speed to match demand — maintaining consistent pressure across multiple outlets while significantly reducing energy consumption.
Because the pump is top-mounted on the tank, the complete system occupies nothing more than the tank’s own 400 × 1050mm footprint — no separate pump base, no pipework run across the floor, and no second position to find in an already tight plant space. The Esybox sits at working height on its mounting platform, with the display, controls and connections all in easy reach. Allow headroom above the tank for the pump when planning the install.
The tank carries a 10-year warranty and the Esybox a 3-year DAB manufacturer warranty. WiFi connectivity via the DConnect app allows remote monitoring, with H2D wireless technology, Google Home and Amazon Alexa voice control. Delivery is typically 1–2 working days.
The 400 Slim tank with the Mini3 vs Esybox pump, plus the natural step up to the 500L Slim. Same 10-year tank warranty across the range.
WB-Advant Slim 400 Mini3 — the lower-cost option on the same 400mm slim tank. Choose where the Mini3’s 50 l/min meets your flow requirement.
WB-Advant Slim 400 Esybox — the higher-flow option on the same 400mm slim tank. 80 l/min at 3 bar, 6.5 bar max, ultra-quiet 43 dB(A), and H2D-ready for later twin upgrade. Choose this where multi-bathroom demand needs more than the Mini3 can deliver.
WB-Advant Slim 500 Esybox — step up to 500L slimline storage where the extra 100mm of tank width is acceptable and more storage buffer matters.
Where does the pump sit?
Will this fit through a standard doorway?
Can the pump be serviced once it’s on top of the tank?
Is 80 l/min enough for my property?
Can I add a second pump later?
What is the Type AB Airgap option?
Can it connect directly to the mains?
What colour options are available?
How does the WiFi and voice control work?
Is the tank WRAS approved?
What warranties are included?
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Esybox Brochure PDFDownload
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Manual PDFDownload
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 – Advant 400 slim Esybox 2604B110TP. 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.



