Sterra's four models compute complete five-year totals of $1,850 to $2,915, using published purchase prices ($599–$1,999) and filter prices/intervals. Coway AIS is priced at $3,088 per the BigGo Singapore aggregator's attribution to "Coway Singapore Official Store" on Shopee — the Shopee listing itself returned no readable content to automated fetching, so this couldn't be independently confirmed on the retailer page. No filter, servicing or warranty cost is published for AIS, so its five-year total ($3,088) is purchase price only. Coway Icon 2 has no published SG price at all; Coway Mate appeared only as an unusable range ($588–$738) on the aggregator. Because two of Coway's three models have no usable price and the third excludes filter cost entirely, nothing on the Coway side can be set against Sterra's complete totals like-for-like. Among models with a complete total, the cheapest is Sterra's Y Tabletop at $1,850.

Sterra's X and Y models name ultrafiltration ("UF Membrane") on their product pages; the Sterra 8 doesn't name its filtration technology. Coway AIS is marketed elsewhere, on Malaysia-market sources not used in this SG dataset, as "6-stage RO filtration combined with dual UV sterilisation," but that claim isn't confirmed on an SG source, so all three Coway models are recorded as unclassified ("other"). Neither brand publishes a scoped certification for any of the seven models in this matchup. Coway Icon 2's own marketing (indexed snippets, not independently re-confirmed on the live page during this pass) describes hot water up to 98°C, "Nanotrap" filtration and a companion "IoCare" app for consumption tracking — not recorded as structured facts here, since the exact source page couldn't be reloaded to confirm current wording.

Coway AIS and Icon 2 are tank-based hot/cold/ambient units; AIS adds a bullet-ice maker. Coway Mate is a non-electric, mains-pressure, ambient-only dispenser. Sterra's Sterra 8 is tankless hot/cold/ambient; its X Standing, X Tabletop and Y Tabletop are tank-based, also hot/cold/ambient.

Sterra publishes full dimensions for all four models (weight is the only field missing, on the Y Tabletop) — the 8 is the smallest at 150×370×392mm, 6.7kg. Coway publishes no width, depth, height or weight for any of its three models on an SG-official or SG-retailer source. On installation fee, Sterra states $0 for all four models; Coway states none for any of its three.

Both brands confirm in-house field service — Sterra via its own hiring pages for installer/technician roles, Coway via its Heart Service page, which states a Coway technician visits the customer's home for filter changes. Sterra publishes an exact warranty term and its exclusions for every model (three years on the 8; one year plus a paid extension on the X/Y range). Coway publishes no warranty-years figure for any of its three models here.