WaterBoost WB – Advant 400 slim mini3 2104B210SL

Name: WaterBoost WB – Advant 400 slim mini3 2104B210SL
Brand: WaterBoost
SKU: WBK400mini3sl
Price: 1094.21 GBP
Availability: InStock

WaterBoost WB – Advant 400 slim mini3 2104B210SL - Image 3

WaterBoost WB – Advant 400 slim mini3 2104B210SL - Image 4

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Established 1975
Trusted by thousands of customers

The WaterBoost WB-Advant Slim 400 Mini3 is the narrowest tank in the entire WaterBoost range — a compact, ultra-slim water boosting system for domestic properties with severely restricted access. A 400-litre WRAS-approved UK-manufactured Advant slimline tank (400mm W × 1050mm L × 1253mm H) pairs with the DAB Esybox Mini3 external variable speed pump, delivering 50 l/min at 3 bar and up to 5.5 bar maximum — with WiFi, DConnect app, 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. The Esybox Mini3 sits alongside the tank for full pump accessibility, running at a quiet 45 dB(A). The tank connects directly to the mains via the pre-fitted ¾” ball float valve, with 1.5” outlet. All interconnecting pipework is supplied — no site assembly required.

The UK-manufactured tank carries an outstanding 10-year warranty and the DAB Esybox Mini3 a 3-year warranty. Delivery is typically 1–2 working days.

50l/min

@ 3 bar

400L

Tank storage

400mm

Slim width

10yr

Tank warranty

362mm doorway clearance
WiFi · Google · Alexa
WRAS tank & pump
5.5 bar max
By-law 30 kit included
Type AB Airgap available
UK-manufactured
1–2 day delivery

Full Description

More about this product

Full Description

Product overview

The WaterBoost WB-Advant Slim 400 Mini3 is the narrowest tank in the entire WaterBoost range — an ultra-compact slimline water boosting system combining a 400-litre WRAS-approved slimline storage tank with the DAB Esybox Mini3 variable speed pump. It is engineered for smaller domestic properties, retrofits and installations with severely restricted access — where even the 500L Slim can’t squeeze through.

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 50 l/min at 3 bar, the Esybox Mini3 continuously adjusts its speed to match demand — maintaining consistent pressure across multiple outlets while using significantly less energy than fixed-speed alternatives. The external pump is mounted alongside the tank for easy access and servicing.

The tank carries a 10-year warranty and the Esybox Mini3 a 3-year DAB manufacturer warranty. WiFi connectivity via the DConnect app allows remote monitoring, with Google Home and Amazon Alexa voice control. Delivery is typically 1–2 working days.

400^L

Tank storage

50^l/min

Flow @ 3 bar

400^mm

Slim width

45^dB

Pump noise at 1m

Tank WRAS approved · Pump WRAS approved

What’s included

DAB Esybox Mini3 booster pump

Variable speed pump delivering 50 l/min at 3 bar, 5.5 bar max working pressure. Built-in inverter, WiFi (DConnect app), Google Home, Alexa, 45 dB(A). 3-year DAB warranty. Pre-fitted with plug.

400-litre Advant slimline storage tank

WRAS-approved 400-litre slimline Advant tank — 400mm W × 1050mm L × 1253mm H. Pre-fitted with By-law 30 kit (By-law 60 in Scotland), ¾” ball float valve, and 1.5” outlet. UK manufactured, 100% rust-proof, 10-year tank warranty. All interconnecting PVC pipework included. Available in boat blue, black or natural.

Key features

Narrowest tank in the range — 400mm

At just 400mm wide, this is the narrowest WaterBoost tank available — passing through standard 762mm doorways with a huge 362mm to spare, plus loft hatches, cellar routes, and access points nothing else can reach.

400L WRAS-approved tank

100% rust-proof, UK manufactured, 10-year warranty. Suitable storage buffer for smaller properties or supplementary use.

Variable speed — 50 l/min @ 3 bar

Esybox Mini3 adjusts speed to match demand — constant pressure at every outlet, up to 50% energy saving over fixed-speed systems.

WiFi and voice control

DAB DConnect app for remote monitoring and pressure adjustment. Google Home and Amazon Alexa compatible.

45 dB(A) — quiet operation

Compact, quiet pump suitable for garages and plant rooms close to living areas.

External pump — easy servicing

The Mini3 sits alongside the tank — fully accessible for inspection, adjustment, and replacement without disturbing the tank.

Type AB Airgap available

Optional Type AB Airgap fitting available for Fluid Category 5 protection — suitable for the most stringent water regulations compliance scenarios.

Dual warranty

10-year tank warranty + 3-year DAB manufacturer pump warranty when purchased from Anglian Pumping Services.

Ready to install

Pre-fitted By-law 30 kit (60 in Scotland), ¾” ball float valve, 1.5” outlet, and all tank-to-pump PVC pipework included. Minimal on-site assembly.

Typical applications

Extreme access restrictions

Properties where even 500mm-wide tanks can’t squeeze through — the 400mm profile is the last resort for the tightest installations.

Smaller domestic properties

1–3 bedroom homes where 400L storage covers demand and the smaller footprint suits a compact plant room or airing cupboard.

Loft & cellar installs

Loft hatches and cellar staircases where the physical opening is under 500mm — only the 400mm profile can pass.

Retrofits & refurbishments

Replacing older cold-water storage in tight airing cupboards, boxed-in stairwells, or purpose-built compact plant rooms.

Water Regulations compliance

The break tank arrangement ensures full compliance where direct mains boosting is not permitted. Optional Type AB Airgap adds Fluid Category 5 protection.

Supplementary storage

Where existing storage needs boosting or an additional buffer — the compact 400L tank slots into spaces others simply can’t.

Technical specifications

Esybox Mini3 pump

Flow rate	50 l/min @ 3 bar
Max pressure	5.5 bar
Pump type	Variable speed — external
Noise	45 dB(A) at 1m
Connectivity	WiFi — DConnect, Google, Alexa
Supply	240V, 50Hz — pre-fitted plug
WRAS	Yes
Warranty	3 years (DAB)

Storage tank

Capacity	400 litres
Dimensions (W × L × H)	400mm × 1050mm × 1253mm
Material	WRAS-approved polymer, UV stabilised
Colours	Boat blue, black or natural
Screw lid	255 mm
Outlet	1.5”
Construction	100% rust-proof, UK manufactured
Included	By-law 30 kit (60 in Scotland), ¾” ball float valve, PVC pipework
Optional	Type AB Airgap (Fluid Category 5)
Warranty	10 years

!The Esybox Mini3 cannot connect directly to the mains. The tank must be supplied from the mains water inlet and the pump draws from the tank. In-service weight (filled) is approximately 450kg — confirm floor loading before install.

How it compares

The Mini3 pump across three slimline tank sizes — same variable-speed performance, same 10-year tank warranty. The choice comes down to storage capacity and access width.

Feature	WB-Advant Slim 400 Mini3 this product	WB-Advant Slim 500 Mini3	WB-Advant Slim 1000 Mini3
Tank width	400mm	500mm	600mm
Doorway clearance (762mm)	362mm	262mm	162mm
Tank capacity	400L	500L	1000L
Tank height	1253mm	1250mm	1703mm
Pump	DAB Esybox Mini3	DAB Esybox Mini3	DAB Esybox Mini3
Flow rate	50 l/min @ 3 bar	50 l/min @ 3 bar	50 l/min @ 3 bar
Max pressure	5.5 bar	5.5 bar	5.5 bar
Type AB Airgap available	Yes — optional	Yes — optional	Check
Tank warranty	10 years	10 years	10 years

Which should I choose?
WB-Advant Slim 400 Mini3 — the narrowest in the range at 400mm wide with 362mm doorway clearance. Choose this only when access is genuinely severe or the property demand suits a compact 400L buffer.
WB-Advant Slim 500 Mini3 — the natural next step up at 500mm wide and 500L capacity. Choose where access allows an extra 100mm and you want more storage buffer.
WB-Advant Slim 1000 Mini3 — step up to 1000L slimline storage (600mm wide) where higher storage buffer matters — larger properties, slow-filling mains, or multi-bathroom demand.

Frequently asked questions

Will this fit through a standard doorway?

At 400mm wide, absolutely — and then some. A standard 762mm (30″) internal doorway gives 362mm of clearance, so awkward corners, tight hallway turns, loft hatches, and narrow cellar access are all handled easily. The 1253mm overall tank height also passes under low soffits comfortably. This is the tank to specify when nothing else will fit.

Is 400L enough storage for my property?

400L is suitable for smaller domestic properties — typically 1–3 bedroom homes with normal simultaneous demand and a mains supply that refills at a reasonable rate. As a rule of thumb, 400L covers around 10–15 minutes of peak simultaneous demand before refilling. For larger properties or where the mains is slow, consider the WB-Advant Slim 500 Mini3 or the WB-Advant Slim 1000 Mini3. Contact us for sizing advice.

What is the Type AB Airgap option?

The Type AB Airgap is an optional fitting that provides Fluid Category 5 protection — the highest level of backflow protection defined by the Water Regulations. It ensures the mains supply cannot be contaminated by any water in the tank under any conceivable failure. Required for the most stringent regulatory scenarios — contact us if you need this specification.

Can it connect directly to the mains?

No — the Esybox Mini3 cannot connect directly to the mains. The mains supply fills the tank via the pre-fitted ball float valve, and the pump draws from the tank. This ensures full compliance with Water Regulations and provides a storage buffer for peak demand periods.

What colour options are available?

The tank is available in boat blue (WaterBoost brand colour), black, or natural. Colour options for the 400 Slim are limited to these three — contact us if you need different requirements.

How does the WiFi and voice control work?

The DAB Esybox Mini3 connects to the DConnect app via built-in WiFi for remote pressure monitoring, adjustment, and fault alerts. It also integrates with Google Home and Amazon Alexa — say “Hey Google, power shower” to boost pressure, or “Hey Google, sleep mode” to quieten it at night.

Is the tank WRAS approved?

Yes — the storage tank is manufactured from WRAS-approved polymer and is fully compliant for potable water storage. The DAB Esybox Mini3 pump is also WRAS approved for potable water use.

Can the pump be replaced independently if it fails?

Yes — the Esybox Mini3 is an external pump mounted alongside the tank and can be disconnected and replaced independently. A pump fault does not require replacing the entire system.

What warranties are included?

10 years on the storage tank, and 3 years DAB manufacturer warranty on the Esybox Mini3 pump — both when purchased from Anglian Pumping Services.

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Delivery Information

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 mini3 2104B210SL. 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.

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