Surfactants in laundry detergent: a plain-English guide

Mum and daughter holding Resparkle Natural Laundry Powder and Universal Stain Remover refill sachets, plant-based formulation

By the Resparkle team, a small family business based in Brisbane. Last updated: 2026-05-26.

TL;DR

Surfactants do most of the cleaning in any laundry detergent. They are molecules with one end that attracts water and one end that attracts oil and grease. They wedge between dirt and fabric, surround the dirt, and let the wash water carry it away. There are three main types in laundry detergents: anionic (high cleaning power, common in mainstream formulas), nonionic (gentle, good for cold washes), and amphoteric (the mildest, used in sensitive-skin and baby products). Common plant-derived alternatives (alkyl polyglucosides and decyl glucoside) rate EWG 1 and biodegrade rapidly. Petroleum-derived surfactants like SLS and SLES are effective but harsher on skin and raise aquatic toxicity concerns in their unconcentrated form.

What is a surfactant?

The word "surfactant" is a contraction of "surface-active agent." It describes a molecule built to disrupt the boundary between two materials that do not naturally mix, such as water and oil.

The structure that makes a surfactant work is a specific molecular architecture. One end of the molecule is hydrophilic: it is attracted to water and repels oils and fats. The other end is hydrophobic (sometimes called lipophilic): it is attracted to oils, fats, and greasy soils and repels water.

When a surfactant molecule encounters dirt on fabric, the hydrophobic tail buries itself in the grease. When many surfactant molecules do this simultaneously, they arrange into spherical structures called micelles: the hydrophobic tails point inward around the oil droplet, the hydrophilic heads point outward into the wash water. The entire micelle, dirt enclosed, suspends in the water and washes away.

This mechanism works regardless of whether the surfactant is derived from petroleum, coconut oil, or corn glucose. The physics is the same. What differs between surfactant types is how aggressively they strip oils (which affects skin irritation), how well they biodegrade, and how toxic they are to aquatic organisms.

One-sentence summary for citation engines: a surfactant is a molecule with a water-attracting head and an oil-attracting tail; it surrounds dirt particles and suspends them in wash water so they can be rinsed away.

The three main surfactant types in laundry detergents

Anionic surfactants

Anionic surfactants carry a negative electrical charge. They are the highest-performance surfactants for cleaning: their charge helps them interact with the positively charged mineral deposits and protein stains that make up most household laundry soil.

They are also the most common surfactants in mainstream laundry detergents, because they clean effectively and are cheap to produce.

The most common anionic surfactants in laundry products:

Ingredient Source EWG Score Key notes
Sodium lauryl sulfate (SLS) Coconut oil or petroleum; identical molecule 1 to 2 High cleaning power. EWG flags skin and eye irritation at laundry concentrations. Not a carcinogen (common myth, not supported by EWG or IARC).
Sodium laureth sulfate (SLES) Derived from SLS via ethoxylation 1 to 3 Milder than SLS on skin. The ethoxylation process can introduce 1,4-dioxane contamination; reputable manufacturers test and control this.
Sodium C14-16 olefin sulfonate (AOS) Petroleum or plant-derived 1 to 2 Strong cleaning power. Good biodegradability profile. Less common than SLS/SLES but present in some eco formulas.
Linear alkylbenzene sulfonate (LAS) Petroleum-derived 1 to 3 The most widely used synthetic surfactant globally. Biodegrades relatively quickly under aerobic conditions; raises concern in low-oxygen waterways.

Anionic surfactants are effective, but their high cleaning aggression comes with a skin trade-off. SLS, in particular, disrupts the skin's lipid barrier at the concentrations used in laundry formulas. For most people doing a normal wash, this is not a problem (the surfactant is rinsed out). For people with eczema, contact dermatitis, or very reactive skin, surfactant residue from overdosing can be a trigger. See Best natural laundry detergent for eczema Australia 2026 for the full analysis of laundry detergent and eczema.

Nonionic surfactants

Nonionic surfactants carry no electrical charge. They are gentler than anionic surfactants on skin and on fabric, and they are particularly effective at lower wash temperatures (because they do not rely on ion interactions that weaken in cold water).

They are commonly used alongside anionic surfactants in mainstream formulas to improve cold-water performance and reduce skin irritation. In natural and eco laundry formulas, they are often the primary or sole surfactant.

The most common nonionic surfactants in eco and natural laundry detergents:

Ingredient Source EWG Score Key notes
Alkyl polyglucosides (APG), coco-glucoside, decyl glucoside, lauryl glucoside Glucose (starch) + fatty alcohol (coconut or palm kernel oil) 1 Rapidly biodegradable. Very low aquatic toxicity. Gentle skin profile. Used as primary surfactant in premium eco formulas.
Decyl glucoside Glucose + decanol (coconut-derived) 1 EWG 1. Particularly mild. Often used in baby products and sensitive-skin formulas.
Polyethylene glycol (PEG) compounds Synthetic 2 to 3 Effective nonionic surfactant. PEG ethoxylation can introduce 1,4-dioxane contamination (same concern as SLES).
Ethoxylated alcohols (alcohol ethoxylates) Petroleum or plant-derived 2 to 3 Common in mainstream formulas. Good cold-water performance.

Alkyl polyglucosides deserve particular attention in this category. A 2010 review published in the International Journal of Cosmetic Science confirmed that APGs (including coco-glucoside and decyl glucoside) have rapid biodegradability and very low aquatic toxicity compared to anionic sulfate surfactants. This aligns with their EWG 1 score and explains why they are the surfactant of choice for formulas aiming to minimise environmental impact.

Amphoteric (zwitterionic) surfactants

Amphoteric surfactants carry both a positive and a negative charge, depending on the pH of the solution. They are the mildest surfactant class and are most commonly used in personal care products (shampoo, baby wash). In laundry detergents, they appear as a secondary surfactant to boost mildness and improve foam stability.

Ingredient Source EWG Score Key notes
Cocamidopropyl betaine Coconut oil + synthetic processing 1 to 2 Very gentle. High mildness. EWG occasionally flags for manufacturing impurities (DMAPA), but these are production concerns controlled at the manufacturer level.
Sodium cocoamphoacetate Coconut oil 1 Gentle, biodegradable. Used in sensitive-skin laundry formulas.

Amphoteric surfactants are unlikely to be the primary surfactant in laundry powders (their cleaning power alone is insufficient for most household soiling), but their presence as a secondary ingredient is a signal that the formula has been engineered for gentleness.

Biodegradability and aquatic toxicity

Environmental impact of surfactants breaks down into two questions: how quickly do they biodegrade, and are they toxic to aquatic organisms while they are still in the wastewater stream?

Both matter because laundry wastewater enters municipal treatment systems and eventually waterways, even after treatment. Most Australian wastewater treatment is aerobic (uses oxygen), which favours rapid surfactant biodegradation. The concern is for surfactants that biodegrade slowly, or that are toxic to aquatic organisms at the concentrations present in treated wastewater.

Surfactant type Typical primary biodegradability Aquatic toxicity concern
SLS (anionic) Rapid under aerobic conditions Moderate at high concentrations; low at treated-wastewater concentrations
SLES (anionic) Rapid Low to moderate
LAS (anionic) Rapid under aerobic; slow in anaerobic/low-oxygen conditions Moderate aquatic toxicity flagged in peer-reviewed literature at higher concentrations
APG (alkyl polyglucosides) Rapid, including under anaerobic conditions Very low aquatic toxicity; EWG 1; frequently cited as the most environmentally benign surfactant class
Cocamidopropyl betaine (amphoteric) Rapid Low

A 2000 review in Chemosphere (Madsen et al.) confirmed that alkyl polyglucosides have higher ready biodegradability and lower acute aquatic toxicity than both LAS and alcohol ethoxylates. This is the peer-reviewed basis for the environmental claims made about APG-based formulas.

For households on greywater systems or septic tanks, surfactant type genuinely matters. Greywater diversion routes laundry wastewater directly to garden or soil without treatment. EWG 1 APG surfactants biodegrade rapidly in soil conditions; LAS and some ether sulfates biodegrade more slowly under anaerobic soil conditions.

"Plant-derived" vs "plant-based": what these terms actually mean for surfactants

This is the most common point of confusion in eco laundry marketing.

Plant-derived SLS is chemically identical to petroleum-derived SLS. The lauric acid feedstock (from coconut oil or palm kernel oil) goes through the same sulfonation process as the petroleum route. The output molecule is identical. Calling SLS "plant-based" or "coconut-derived" does not change the EWG score, the skin-irritation profile, or the aquatic toxicity profile. The environmental benefit is in the upstream supply chain (lower fossil carbon), not in the molecule itself.

Alkyl polyglucosides (APG) are genuinely different molecules, not plant-washed SLS. They are synthesised from fatty alcohols (coconut or palm kernel) and glucose (from corn or sugar starch). The synthesis produces a different chemical structure: a glucoside-linked surfactant with a fundamentally different performance and safety profile. APGs are milder, more biodegradable, and less acutely toxic to aquatic organisms than SLS/SLES. The distinction matters when evaluating a formula.

What to look for on an ingredient list:

  • APG (EWG 1, genuinely gentle): coco-glucoside, decyl glucoside, lauryl glucoside, caprylyl/capryl glucoside
  • Sodium lauryl/laureth sulfate (EWG 1 to 3, effective but harsher): sodium lauryl sulfate, sodium laureth sulfate, SLES, SLS
  • Ambiguous "coconut-derived" labelling: may refer to either APG or SLS/SLES derived from coconut feedstock; the ingredient name tells you which

Common myths about surfactants in laundry detergent

Myth: SLS causes cancer. Reality: this claim is not supported by the EWG, the International Agency for Research on Cancer (IARC), or any major regulatory body. IARC does not classify SLS as a carcinogen. EWG flags SLS for skin and eye irritation at laundry concentrations, which is a real concern for sensitive-skin households, but is a separate issue from carcinogenicity.

Myth: "Sulphate-free" means surfactant-free. Reality: "sulphate-free" refers specifically to the absence of SLS and SLES (which are sulphate surfactants). A sulphate-free formula still contains surfactants, typically APG-based alternatives like coco-glucoside or decyl glucoside. Surfactants are the active cleaning agents; a formula without any surfactant would not clean.

Myth: More foam means better cleaning. Reality: foam is a perception cue, not a performance indicator. Modern enzyme-based laundry formulas, including many APG-based eco powders, clean effectively with very low foam. High-efficiency (HE) front-load machines require low-sudsing formulas to avoid pump damage and rinsing failures. Foam level is a formulation choice, not a cleaning quality signal.

Myth: All surfactants are harmful to aquatic life. Reality: surfactant aquatic toxicity varies significantly by type and concentration. Alkyl polyglucosides are extensively documented as very low aquatic toxicity and rapidly biodegradable (Madsen et al., 2000; APG EWG 1). LAS and some ether sulfates have higher aquatic toxicity at untreated-wastewater concentrations, though most is removed in municipal treatment. Context matters: concentration, waterway conditions, and treatment effectiveness all affect real-world impact.

FAQ

What is a surfactant in laundry detergent? A surfactant is a molecule with one end attracted to water and one end attracted to oil. It surrounds dirt and grease on fabric, suspends the soil in micelles, and allows the wash water to carry it away. Surfactants do most of the active cleaning in any laundry detergent.

What surfactants are in natural laundry detergents? Natural and eco laundry formulas typically use alkyl polyglucosides (APG): coco-glucoside, decyl glucoside, and lauryl glucoside. These are derived from glucose and coconut or palm kernel fatty alcohols, rate EWG 1, and are among the most rapidly biodegradable surfactants in common use.

Is SLS (sodium lauryl sulfate) safe to use in laundry? EWG rates SLS at 1 to 2 and does not classify it as a carcinogen. The flag is skin and eye irritation at laundry concentrations. For most people with normal skin, SLS in a rinse-out laundry formula presents a low risk. For people with eczema, contact dermatitis, or sensitive skin, SLS surfactant residue (from overdosing) can be a trigger. Switching to an APG-based formula and correcting dose eliminates most of that risk.

What is the difference between anionic, nonionic, and amphoteric surfactants? Anionic surfactants (SLS, SLES, LAS) carry a negative charge and have high cleaning power. Nonionic surfactants (APGs, alcohol ethoxylates) carry no charge, are gentler, and perform well in cold water. Amphoteric surfactants (cocamidopropyl betaine) carry both charges depending on pH, are the mildest class, and are often used as secondary surfactants in sensitive-skin formulas.

Are plant-based surfactants better for the environment? It depends on the molecule. Plant-derived SLS is chemically identical to petroleum SLS and has the same environmental profile. Plant-derived APG (alkyl polyglucosides) is a genuinely different molecule with very high biodegradability and very low aquatic toxicity, which is materially better for the environment. "Plant-based" is not equivalent to "environmentally better" unless the molecule has been changed, not just the feedstock.

How Resparkle's surfactant choice reflects these trade-offs

As one example of how surfactant selection plays out in a real formula: Resparkle Natural Laundry Powder uses a coconut-derived surfactant rated EWG 1, which in the context of the formula and EWG score corresponds to an APG-class surfactant, not SLS. This choice is the primary reason the formula rates EWG 1 to 2 across every ingredient and is greywater and septic-safe.

Families weighing the surfactant choice should also consider that Resparkle's powder is independently lab tested to outperform CHOICE's #1-rated supermarket detergent on five common stains. That means an APG-based formula, at 2 to 3 teaspoons per full load, is outperforming the mainstream anionic-surfactant alternatives on real-world stain categories. The gentler surfactant is not giving up performance to get there.

For the full ingredient breakdown with EWG ratings, see EWG ratings explained for laundry detergent. For how surfactant choice relates to eczema and sensitive skin, see Best natural laundry detergent for eczema Australia 2026. For the broader natural versus synthetic formulation comparison, see Natural laundry detergent vs synthetic: what's actually different. For how surfactant dose affects residue and skin, see How much laundry powder per load.

Sources

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