If you're looking at one of our ultrafiltration systems and the spec sheet mentions a minimum water pressure, you've probably realized you have no idea what your actual number is. Most people don't. Water pressure isn't something you think about until a system depends on it, and by then it's a little late to guess.

The good news is checking it takes about five minutes, and there are two honest ways to do it: buy a cheap gauge, or ask us to bring one.

Why water pressure matters for a drinking water system

Our Evans 3-Stage and Evans 5-Stage ultrafiltration systems run entirely on your building's own water pressure: no pump, no outlet, nothing to plug in. That's most of what makes them the cheapest systems on our menu to buy and to run. But it also means they need the building to actually supply enough pressure to push water through the membrane, and Evans specifies a minimum of 20 PSI for both systems. Below that, flow at the faucet gets noticeably weak, or the system may not perform as designed at all.

Our reverse osmosis systems don't have this problem the same way. The Purikor 5-Stage and Purikor 6-Stage both include a booster pump, so they only need 15 PSI minimum. If your apartment turns out to be genuinely low-pressure, that's actually a case where reverse osmosis can be the more reliable choice — the opposite of the usual advice, which defaults everyone to ultrafiltration first.

The cheap way: a pressure gauge from Amazon

Search Amazon México for “manómetro de presión de agua” and you'll find inexpensive screw-on gauges made for exactly this. Look for one described as coming with multiple adapters or attachments. CDMX taps and hose bibs use a few different thread sizes, and a gauge that only fits one won't necessarily fit yours. A basic one reads in both PSI and bar, worth having since most plumbing fittings here are labeled in metric.

To use it: screw the gauge onto an outdoor spigot or a washing-machine valve if you have one (anywhere with a standard hose thread works), open the valve fully, and read the number. If you only have indoor taps without hose threads, the same gauges usually include a faucet adapter for that too. Either way, you're looking for a number at or above the minimum your system needs.

The free way: we'll check it for you

If you're inside our service area, message us and we'll bring a gauge and check your pressure at no cost. No strings attached, whether or not you end up booking a system. It takes us a couple of minutes on an install visit, and it's a small thing next to the cost of finding out afterward that a system doesn't perform the way it's supposed to.

We currently serve:

  • Core zone (fastest response): Roma Norte, Juárez, Roma Sur, Hipódromo, Condesa, and Doctores
  • Extended zone: Escandón, Nápoles, Polanco, and Del Valle

See the full service area map for response times by zone.

Schedule a free pressure check

Why water pressure varies so much across CDMX buildings

We looked into why this number is so inconsistent here, building to building, and it comes down to two things stacked on top of each other.

The first is just how most Mexican homes are plumbed. Pressure in the large majority of Mexico City buildings comes from a rooftop tinaco, not directly off the municipal line. Water gets pumped up once, then falls back down to your taps under gravity. That means your actual pressure depends on how far above your highest tap the tinaco sits, which is why a ground-floor unit and a fifth-floor unit in the same building can read noticeably differently at the kitchen sink, even fed by the identical tank.

The second is specific to this city. Mexico City is sinking: in the worst-affected areas, by close to 50 centimeters a year, a consequence of decades of groundwater extraction from the aquifer beneath the old lakebed the city sits on. A 2021 study in the Journal of Geophysical Research: Solid Earth found the subsidence is effectively irreversible and ongoing. That uneven settling doesn't just crack sidewalks. It stresses buried municipal pipe and building risers, and reporting on the city's water system has documented residents dealing with water that arrives dirty, arrives at reduced pressure, or doesn't arrive at all, with utility crews fixing the same lines only for them to fail again later.

Put together: your pressure depends on your floor, your building's tinaco height, and infrastructure that's aging unevenly under a city that's still settling. None of that is something a gauge fixes. But it's exactly why guessing isn't a great plan, and checking the actual number is.

What to do with your number

If you're at 20 PSI or above, either Evans ultrafiltration system will run as designed. If you're between 15 and 20, ultrafiltration is marginal and reverse osmosis is worth a closer look, since the Purikor systems' booster pump does the work your building pressure can't. If you're below 15, message us before booking anything — that's a conversation worth having before a system goes in, not after.

Either way, our drinking water systems comparison lays out all four options side by side, including the pressure requirement for each.

Sources

  • Chaussard, E., et al. “Over a Century of Sinking in Mexico City: No Hope for Significant Elevation and Storage Capacity Recovery.” Journal of Geophysical Research: Solid Earth, 2021.
  • “Why Mexico City's Water Crisis Is Causing It to Sink,” The Washington Post, June 2024.
  • “Water Pressure Systems versus the Rooftop Tinaco Tank in the Mexican Home,” MexConnect.