Straight answers about the open-standard under-sink RO system. No marketing fluff.
What does 800 GPD actually mean?
GPD = gallons per day. An 800 GPD RO membrane is rated to produce up to 800 gallons of purified water per day under standard test conditions — enough flow that you fill a glass in seconds instead of waiting for a storage tank to refill. The rating is a laboratory number: real output at home moves with feed pressure, water temperature, and how spent the pre-filters are. In practice it means headroom — drinking and cooking for a household without a tank dictating the pace. Match the membrane to the household: 1–2 people typically need 400–600 GPD, and 3–5 people 600–800 GPD. Households on lower feed pressure will see less than the rating, which is why matching the membrane to your water pressure matters as much as the number on the box.
Yes. EasyToReplace uses universal 10-inch drop-in housings, so any standard 10" × 2.5" sediment, carbon-block, or RO cartridge from any supplier drops in. You are never forced to buy branded refills. The 10-inch by 2.5-inch size is the shared standard behind most under-sink systems, including most iSpring, APEC, and Express Water models, and the same cartridges are stocked by suppliers everywhere. Checking your own system takes ten seconds: measure the cartridge — 10 inches long, 2.5 inches wide — and if it matches, the format is standard at every stage. If it measures differently, or your system uses sealed pods or inline cartridges, ours will not fit. Sediment, carbon-block, and membrane stages all follow the same standard sizes, so that one measurement settles the whole system. It also means replacements stay available even if a single brand discontinues a model line.
Rule of thumb: sediment pre-filter every 3–6 months, carbon block every 6–12 months, RO membrane every 2–3 years. Your TDS meter is the honest signal — when filtered-water TDS climbs noticeably above your baseline, a filter is spent. Treat the calendar as a reminder and the meter as the verdict: measure tap and filtered water, compute the rejection rate, and compare it with your baseline. The stages also protect each other in order — sediment catches grit before it scars the carbon block, and the carbon block strips chlorine before it reaches the membrane — so changing cheap pre-filters on time is what lets the membrane reach its full 2–3 years. Change pre-filters first, retest, and replace the membrane only if rejection stays low. When in doubt, test rather than guess — the meter reading takes thirty seconds and settles the argument.
TDS (total dissolved solids), measured in ppm, tells you how much dissolved mineral and salt content is in your water. A rising TDS in your filtered water usually means a pre-filter is spent or the RO membrane is aging — it is the simplest health check for your system. Two cautions keep the number honest: TDS is not a safety test — a low reading does not prove water is safe, and a high one does not prove it is dangerous — and the trend matters more than the absolute number. Measure tap and filtered water and compute rejection: (tap − filtered) ÷ tap × 100. A healthy RO rejects 90–98%. The EPA's secondary guideline for TDS is 500 ppm, mostly about taste. A TDS pen costs about $15 and stays useful for years of checks.
Our housings contain no chip authentication. Any standard 10-inch cartridge works — there is no DRM handshake that rejects a third-party filter. Some modern appliances read a chip on every refill and refuse anything the manufacturer did not sell; a system built on the universal 10-inch standard has nothing to read and nothing to refuse. If a 10-inch by 2.5-inch sediment, carbon-block, or membrane cartridge fits the housing, it filters — whoever made it and whoever sold it. That applies to our own filters too: the subscription, at $29 every 6 months, is a convenience, not a requirement. Lock-in needs proprietary shapes or electronics; this system has neither, by design. There is no activation step, no registration, and no account required before a cartridge starts filtering.
Every fitting is a standard off-the-shelf push-fit part. If an elbow leaks years from now, you swap a ~$0.80 standard elbow in 30 seconds — you never throw the whole machine away. Housings, tubing, and cartridges are all standard sizes shared across brands, so a worn part is a small standard purchase, not a brand-only order at a brand-set price. Nothing is glued shut or keyed with chips, and the open frame leaves every connection reachable with basic tools. Any stage can be opened, inspected, flushed, and replaced on its own schedule: if a part ever does fail, you replace the part — not the purifier. The fittings are the same standard parts sold for any brand's system, available from any supplier, not a special order from us. A housing wrench and basic hand tools are all any of it ever needs.