Best value — cheapest to own
Evans 3-Stage Ultrafiltration System
Model UF-3
The Evans 3-Stage is our entry-level drinking water system — sediment, carbon, and an ultrafiltration membrane rated to 0.01 microns, fine enough to remove bacteria and cysts from your water. It runs purely on your building's water pressure, so there's no pump, no outlet, and nothing to plug in. It's also the cheapest of our four drinking water systems to keep running: lowest install price, and the lowest maintenance-plan rate on our menu.
Evans 3-Stage at a glance
The mechanism here is physics, not chemistry: the membrane's pores are rated to 0.01 microns, and the bacteria responsible for most waterborne illness — E. coli, Salmonella, Shigella, Campylobacter — run 0.2 to 10 microns across. They can't fit through. The CDC's own data on travelers' diarrhea puts bacteria behind 75–90% of cases, which is why a hard physical barrier at this scale matters more than any taste or mineral claim.
The same barrier handles Giardia and Cryptosporidium just as decisively — both cysts run 4 to 12 microns, hundreds of times larger than the pore. A systematic review of physiochemical water treatment technologies in Environmental Science & Technology puts membrane filtration's log reduction for protozoa at around 3.0, meaning roughly 99.9% of what enters is caught. Locally, this isn't academic: a study in the International Journal of Food Microbiology testing bottled water from small purification plants around Mexico City found coliform bacteria in 81% of samples and E. coli specifically in 23% — the exact contamination this membrane exists to stop.
Viruses are the one place this system's protection is genuinely partial, and it's worth understanding why rather than taking our word for it. Viruses run 0.02 to 0.4 microns — nominally smaller than the pore, but the smallest are only about twice that size, and no membrane holds a perfectly uniform pore distribution. That's not a flaw specific to this unit; it's true of ultrafiltration as a technology, which is why we don't guarantee virus removal on either of our UF systems and reserve that claim for reverse osmosis instead.
Two things worth knowing before you book, neither obvious from a spec sheet: this system needs at least 20 PSI of water pressure to work properly, since it runs on building pressure alone with no pump — worth checking if you're on a top floor or an older gravity-fed tinaco system, both common in CDMX. Not sure what yours actually is? Here's how to check it — a cheap gauge, or we'll check it for free if you're in our service area. This system also carries a 1-year manufacturer warranty from Evans, on top of whatever we cover on the install itself.
See the full comparison across all four systems for what “partial” and “final-stage UV” mean in practice.
Benefits
- Removes bacteria and parasitic cysts — real protection, not just better taste
- No electricity required — installs almost anywhere under your sink, and never stops working during a power outage
- Doesn't waste water during operation, unlike a reverse osmosis system
- The lowest cost to own on our menu — cheapest to install, and the lowest maintenance-plan rate of any drinking water system we carry
- Fast install, minimal disruption to your kitchen
- A trusted, widely-used brand in the Mexican market
What's included
- Full installation by an English-speaking technician — no translation apps, no confusion explaining a plumbing issue
- A quick walkthrough of your system — including the commissioning flush we run before you drink from it, so you know what we did and why
- Optional maintenance plan — we'll track your filter schedule and reach out when it's due, so you never have to think about it
- Requires drilling a small hole for the dedicated faucet, unless one is already in place — worth checking with your landlord if you're renting.
Maintenance
Sediment and carbon block replaced every 6 months; the ultrafiltration membrane annually. Our maintenance plan is $175/mo, billed every 6 months at $1,050 alongside your visit — a flat rate averaged across the schedule, so it never changes visit to visit. It's the least expensive of our four drinking water systems to maintain, on top of being the least expensive to install.
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See details & pricing FlagshipPurikor 6-Stage Reverse Osmosis + UV System
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The Purikor 6-Stage builds on everything the 5-Stage RO does — bacteria, cysts, viruses, and dissolved solids like heavy metals and fluoride…
See details & pricingReady to book this install?
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