Sterra's purchase prices run from $599 (Y Tabletop) to $1,999 (Sterra 8). Because every Sterra model publishes both a filter price and a replacement interval, a complete five-year total can be computed for each: $1,850 (Y Tabletop), $2,400 (X Tabletop), $2,500 (X Standing) and $2,915 (Sterra 8). Wells' purchase prices run from $780 (Mini) to $2,080 (Slim One), but none of the three models has a published filter price, so the five-year total for each — $780, $1,880 and $2,080 — is the purchase price alone. It is not a genuine cost of ownership and shouldn't be read against Sterra's complete totals. Separately, Wells' own structured product data marks its prices as excluding GST ("valueAddedTaxIncluded": false); whether checkout adds GST on top of the listed figure isn't published. Among models with a complete, comparable five-year figure, the cheapest here is the Sterra Y Tabletop at $1,850.

Sterra names ultrafiltration ("Nano Filter UF Membrane") on the X and Y product pages; the Sterra 8's filtration technology isn't named on its page at all and is recorded as unclassified rather than guessed. Wells describes its cartridges only by branded names like "Carbon and Neo Nano Clean" across all three models, without stating whether they're RO, UF, carbon or ceramic — all three are recorded as unclassified too. Neither brand publishes a scoped certification (an NSF/ANSI-style standard with a stated tested claim) for any model in this matchup; both certification lists are empty.

Sterra covers both formats: the 8 is tankless and connects directly to the mains; the X Standing, X Tabletop and Y Tabletop are tank-based (Y refills manually; the X pair connect to the mains). All four output hot, cold and ambient water. Wells is tankless across the board. The Mini is a passive, non-electric, ambient-only dispenser — no hot or cold function — which is why it's the cheapest model in the Wells lineup. Slim One and True Tankless Cooling+ both do hot/cold/ambient; Slim One publishes eight discrete temperature presets, and True Tankless Cooling+ publishes seven, including a 10°C cold and an 8°C "super cool" setting — more temperature detail than is published for any Sterra model.

Sterra 8 is the brand's smallest unit at 150×370×392mm and 6.7kg, tankless and countertop. The X Standing is a 1,115mm floor-standing tower (22kg); X Tabletop and Y Tabletop are countertop tank units around 300–310mm wide. Wells Mini is narrower still at just 90mm wide (301×313mm depth/height) — the tightest footprint of any model in this comparison. Slim One (160×450×360mm) and TT Cooling+ (190×520×405mm) are larger countertop units. Sterra publishes a $0 installation fee for all four models, though drilling or relocation work isn't separately quantified; Wells publishes no installation fee for any of its three.

Sterra states its warranty terms in writing for every model: three years on the Sterra 8 (parts, labour and technician visits fully covered in year one; an $80 site-visit fee applies from year two), one year plus an optional paid extension of up to two more years on the tank models, with filter/hose wear-and-tear explicitly excluded throughout. Sterra also confirms in-house service technicians via its own hiring pages. Wells publishes no warranty duration, coverage or installation-fee figure for any of its three models — no dedicated warranty page exists on wellssingapore.com as of this check — and its service model, in-house or contracted, isn't stated either.