Household cleaning
Harpic Power Plus Original dupe
Why pay around £2.50 for Harpic? The bulk active is Technical hydrochloric acid 32–36% diluted to toilet strength — 73% less per working litre than a typical shelf pack.
From the retail pack to the active and the mix
1 · Retail
Harpic Power Plus Original
750 ml bottle · £2.50 typical snapshot
Water, quat surfactants and perfume
2 · Active
Hydrochloric acid
9% on the label
7647-01-0HCl
Bulk Technical hydrochloric acid 32–36% diluted to toilet strength
3 · Mix
1:3 (≈9% working — toilet band, not brick-acid duty)
£0.90 per working litre · 73% less than the shelf pack
- Active
- Hydrochloric acid
- CAS
- 7647-01-0
- Dupe
- Technical hydrochloric acid 32–36% diluted to toilet strength
- Saving
- 73% / L
Saving is per litre of working-strength mix versus a typical pack price, not versus the DIY kit total. Shop prices move — always check the listing.
Label teardown
What the pack promises versus what the label chemistry actually is.
The marketing claim
“10× better limescale removal”
The chemical reality
Nine grams of hydrochloric acid per 100 g of liquid — toilet limescale and uric scale, not patio brick acid. The same HCl family as Mortar Clen but far weaker and formulated for ceramic WC pans. Dilute 30–36% pool-grade HCl carefully to a similar working strength, or buy labelled toilet acid once and compare the SDS.
Active vs filler
9% Hydrochloric acid · 91% carrier / filler — Water, quat surfactants and perfume
- Typical retail
- £2.50
- 750 ml bottle
- Estimated active cost
- £0.67
- Scaled from bulk £18.00 / 5 litres
- Indicative markup
- 3.7×
- Snapshot maths, not a live shop price
The Marketing Claim & The Catch
A 750 ml bottle pack of Harpic Power Plus Original typically retails around £2.50 in household cleaning. That is a UK shelf-price snapshot for the maths on this page — not a live shop quote or a manufacturer RRP. Listings, sizes and deals move. The marketing line is that you are buying a finished lifestyle product, not a weighed chemical.
On the pack: 10× better limescale removal; Kills 99.9% of bacteria; and Thick liquid clings under the rim.
The catch: Nine grams of hydrochloric acid per 100 g of liquid — toilet limescale and uric scale, not patio brick acid. The same HCl family as Mortar Clen but far weaker and formulated for ceramic WC pans. Dilute 30–36% pool-grade HCl carefully to a similar working strength, or buy labelled toilet acid once and compare the SDS.
- “10× better limescale removal”
- “Kills 99.9% of bacteria”
- “Thick liquid clings under the rim”
Proprietary Blend & Dosage Breakdown
The labelled active is Hydrochloric acid at 9%. Everything else in the pack is water, quat surfactants and perfume.
At 9% active, most of what you pay for is carrier and packaging. The brand is selling convenience, fragrance and a label — not a uniquely potent molecule.
Branded working strength is whatever comes out of the bottle. The bulk alternative is 36% Technical hydrochloric acid 32–36% diluted to toilet strength, mixed to 1:3 (≈9% working — toilet band, not brick-acid duty).
- Labelled active
- Hydrochloric acid
- 9%
- Carrier
- Water, quat surfactants and perfume
- Retail pack
- 750 ml bottle · £2.50
The Active Chemical Alternative (Dupe Stack)
The dupe stack is Technical hydrochloric acid 32–36% diluted to toilet strength at 36% bulk. Indexed as CAS 7647-01-0, formula HCl. Buy it as 5 litres for around £18.00 from Amazon UK.
Working strength: 1:3 (≈9% working — toilet band, not brick-acid duty). Indicative cost £0.90 per diluted litre — 73% below a typical branded pack on a per-litre basis, before you reuse leftover bulk.
Follow the mixing method and the supplier SDS. Wear the listed PPE. Do not mix incompatible oxidisers, acids or ammonia.
- Corrosive. Nitrile gloves, splash goggles, ventilation. Never mix with bleach, ammonia or hypochlorite.
- Same bulk acid as brick acid: 1 part 36% hydrochloric acid + 3 parts water ≈ 9% toilet-strength liquor. Always add acid to water.
- Apply sparingly under the rim, dwell a few minutes, brush, flush. Rinse brush and avoid metal fittings.
- 5 litres of 36% makes about 20 litres of toilet-strength acid. Store locked away from children and pets.
Dilution recipe
0.75 L working batch
Working strength 1:3 (≈9% working — toilet band, not brick-acid duty). Educational estimate from the listed ratio — check the SDS before you mix.
Chemical
188 millilitres
Technical hydrochloric acid 32–36% diluted to toilet strength
Water
0.56 litres
Carrier / diluent
25% concentrate · 75% water by working volume (solids are dissolved into the water share).
Required PPE
Loading calculator…
Side-by-Side Price & Potency Comparison
Head-to-head comparison
| Measure | Retail brandedHarpic | Raw active dupeDupeStack |
|---|---|---|
| Product | Power Plus OriginalAmazon UK search — listing, not a confirmed seller | Technical hydrochloric acid 32–36% diluted to toilet strength |
| Pack / unit | 750 ml bottle · £2.50 | 5 litres · £18.00 |
| Active | Hydrochloric acid at 9%Carrier: Water, quat surfactants and perfume | 36% bulkHCl |
| CAS number | Not disclosed on pack | 7647-01-0 |
| Working strength | Ready-to-use pack | Dilute 1:3 (≈9% working — toilet band, not brick-acid duty) |
| Cost per litre | £3.33 / L typical pack | £0.90 / L mixed from bulk |
| Headline saving | Baseline | 73% cheaper |
| COSHH / PPE | Follow the branded SDS | Gloves. Chemical-resistant gloves (nitrile or neoprene)Eye protection. Indirect-vent splash goggles — not ordinary spectaclesVentilation. Use outdoors or with mechanical extractionAcid-resistant PPE. Apron and gloves rated for corrosive liquids |
Active ingredient and cheaper alternative — FAQ
Is Harpic the same as Everbuild Mortar Clen?
Same acid (HCl, CAS 7647-01-0) but different job and strength class. Harpic is ~9% for toilet ceramic. Mortar Clen is brick acid for cement smears on masonry. Do not use one in place of the other.
Can I mix Harpic with bleach?
Never. Acid plus hypochlorite can release chlorine gas. One product per clean.
How do you mix the Power Plus Original dupe stack?
Corrosive. Nitrile gloves, splash goggles, ventilation. Never mix with bleach, ammonia or hypochlorite. Same bulk acid as brick acid: 1 part 36% hydrochloric acid + 3 parts water ≈ 9% toilet-strength liquor. Always add acid to water. Apply sparingly under the rim, dwell a few minutes, brush, flush. Rinse brush and avoid metal fittings. 5 litres of 36% makes about 20 litres of toilet-strength acid. Store locked away from children and pets.
DupeStack provides chemical concentration data and educational mixing guides only. Wellness pages compare food supplements, not medicines or prescribed treatments. Always review the supplier Safety Data Sheet (SDS) and comply with UK Health and Safety Executive (HSE) and COSHH regulations when handling concentrated substances. Mixing and storage are at your own risk. Some links are affiliate advertisements (Amazon Associates, eBay Partner Network, and Awin when those programmes are live). Commissions do not change listed concentrations or calculator output.
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- Retail pack
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- Raw active
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- Retail pack
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- Raw active
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- Retail pack
- £3.50750 millilitres
- Raw active
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£34.99Save 73% / L
Indicative DIY stack