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What goes in the tank

The best carpet and upholstery solutions for 2026

A spray extraction machine is only as good as what you put in it. We cover low-foam concentrates sized for a machine rather than a bucket, enzyme products for the accidents where ordinary detergent sets the stain, and the dilutions that decide whether a sofa dries clean or dries sticky.

What we recommend

  1. Dirtbusters Clean & Protect 4-in-1, product photograph

    Dirtbusters Clean & Protect 4-in-1

    Five litres of low-foam concentrate — the format that matches a machine rather than a bucket.

    Volume
    5 l concentrate
    Formula
    4-in-1: clean, deodorise, brighten, protect
    Foam
    Low, formulated for extraction machines
    Surfaces
    Carpets, mats, upholstery, car seats
    Part number
    DB-000156
    Amazon reference
    B00MZI9JE8
    EAN
    0700161511031
    • Five litres, which is the format a machine actually consumes
    • Low-foam formulation — the property that protects the recovery pump
    • Five litres is a lot to store if you clean twice a year
    ≈ £18 / 28 €
    Check price on Amazon
  2. Dirtbusters 3-in-1 Concentrate, product photograph

    Dirtbusters 3-in-1 Concentrate

    The odour-first version of the same five litres — which is the problem most people are actually solving.

    Volume
    5 l concentrate
    Formula
    3-in-1: clean, deodorise, freshen
    Surfaces
    Carpets, mats, mattresses, upholstery
    Part number
    DB-000101
    Amazon reference
    B00KQKCM7S
    EAN
    0700161510492
    • Aimed at odour, which is usually the real complaint rather than the visible mark
    • Five litres at a price close to a one-litre retail bottle
    • Verified absent from the US store
    ≈ £23 / 27 €
    Check price on Amazon
  3. Kärcher RM 519N Natural, product photograph

    Kärcher RM 519N Natural

    The original Kärcher solution in a natural formula — and the price varies more between markets than any other product here.

    Volume
    1 l
    Formula
    Natural, fibre-deep action
    Surfaces
    Carpets, upholstery, car seats, shoes, mattresses, curtains
    Part number
    6.296-237.0
    Amazon reference
    B0GKHRKMB6
    EAN
    4066529127846
    • Original formulation, guaranteed compatible with Kärcher spray extraction machines
    • A natural formula on a product that ends up on fabric people sit on
    • One litre is a small format for a machine that uses solution by the tankful
    ≈ £11 / 13 €
    Check price on Amazon
  4. Kärcher RM 519, product photograph

    Kärcher RM 519

    The standard RM 519, whose quick-dry formulation addresses the actual failure mode of this category.

    Volume
    1 l concentrate
    Formula
    Quick-dry
    Surfaces
    Carpets, rugs, upholstery, car seats
    Part number
    RM 519
    Amazon reference
    B00B17MAFE
    EAN
    4039784712669
    • A quick-dry formulation, which targets the real problem: fabric left wet
    • Original Kärcher, so foaming behaviour suits the machines
    • Verified absent from the US store
    ≈ £17 / 14 €
    Check price on Amazon

Which one for which need

Working on a stain that has already dried

A stain several days old needs dwell time, not pressure. Products that state a working time are the ones that recover a forgotten accident.

Kärcher RM 519N Natural

Covering a whole sofa

A three-seater drinks close to two litres of solution, rinse included. The stated volume and dilution say whether one bottle is enough or two are needed.

Dirtbusters 3-in-1 Concentrate

Who each type suits

Spot cleaner
The product must be described as low-foaming and machine-compatible. Foam in the recovery tank rises towards the motor: that is a repair, not an inconvenience.
One-off stain treatment
An aerosol spot remover applied locally avoids wetting a whole sofa for a ten-centimetre stain. Drying time is the real cost of a full clean.
Household with pets
Enzyme formulas attack the organic residue behind the smell, where a conventional detergent cleans the stain and leaves the odour.

The trade-offs to weigh

Cleaning power against residue
A powerful product badly rinsed leaves a film that holds dust: the fabric gets dirty faster than before the clean. The clean-water rinse is the step everyone skips.
Enzymes against speed
Enzyme formulas need real dwell time to work. Rinsing too early amounts to having used nothing at all.
Concentrate against dosing
Concentrate costs far less per usable litre and assumes correct dosing. Overdosing foams and leaves a residue three rinses will not remove.

Questions buyers ask

Can ordinary carpet shampoo go in a spot cleaner?

No, unless it explicitly says "low-foaming" and "machine-compatible". A household shampoo foams in the recovery tank and the foam can reach the motor.

Should I test first?

Always, on a hidden area, and wait for it to dry completely. Some solution-dyed fabrics bleed, and that only shows once dry.

Why does the stain come back as it dries?

That is wicking: liquid that sank into the foam rises again and brings the soiling with it. It comes from insufficient recovery, almost never from the product.

Are enzyme products more effective?

On organic matter — urine, vomit, food — markedly, because they break down what causes the smell. On a grease or ink stain, they add nothing.

Should I rinse after the product?

Yes, a pass with clean water. That is what removes the detergent residue and stops the fabric getting dirty again straight away.

How long before sitting down again?

Until it is completely dry, from a few hours to two days depending on the foam and the ventilation. Sitting on damp fabric drives the soiling back deep into it.

Do these products suit delicate fabrics?

Silk, velvet and fabrics with glued backing often take no moisture at all. The label on the furniture, if there is one, outranks the label on the product.

Does a fragrance-free product clean less well?

No: fragrance cleans nothing, it masks. On a sofa where an animal or a child sleeps, a fragrance-free product avoids adding a smell to the one you meant to remove.

What to remember

The product matters less than the method: low-foaming compulsory in a machine, dwell time respected, a clean-water rinse, then dry passes until the fabric gives nothing more back. It is the recovery, not the formula, that decides the result.

These cleaning machines at a glance

  • Most affordable here: Kärcher RM 519N Natural, at 11 £.
  • Highest Volume in this category: Dirtbusters Clean & Protect 4-in-1 (5 l concentrate).

These cleaning machines, side by side

A figure has to be published by four machines in five to earn its column. Below that, we would be comparing empty cells.

ModelPriceAmazon referenceFormulaSurfacesVolume
Kärcher RM 519N Natural11 £B0GKHRKMB6Natural, fibre-deep actionCarpets, upholstery, car seats, shoes, mattresses, curtains1 l
Kärcher RM 51917 £B00B17MAFEQuick-dryCarpets, rugs, upholstery, car seats1 l concentrate
Dirtbusters Clean & Protect 4-in-118 £B00MZI9JE84-in-1: clean, deodorise, brighten, protectCarpets, mats, upholstery, car seats5 l concentrate
Dirtbusters 3-in-1 Concentrate23 £B00KQKCM7S3-in-1: clean, deodorise, freshenCarpets, mats, mattresses, upholstery5 l concentrate

Where these cleaning machines are covered

  • Choosing a Pressure Washer Detergent | CleanVerdict

Sources and method

Specifications: manufacturer sheets for cleaning machines and the matching Amazon product pages. Prices and availability: Keepa. Every figure in this table names its source.

Most recent revision in this category: August 16, 2026.

How these cleaning machines are assessed here

Prices quoted in these summaries are dated readings. The live price is shown next to each product.