Reverse osmosis, explained without the mystery.
A whole home system makes every tap in the house better. Reverse osmosis exists because the water you actually drink deserves one more standard entirely. It is the same core technology bottled water plants use, shrunk to fit under a kitchen sink.
How it works
Reverse osmosis pushes water through a membrane with pores measured in ten thousandths of a micron. Water molecules pass. Almost everything dissolved in the water does not. A quality RO membrane rejects 95 to 99 percent of total dissolved solids, and that includes the contaminants people worry about most:
- PFAS, the "forever chemicals" showing up in water research nationwide
- Microplastics
- Heavy metals such as lead and arsenic
- Nitrates, fluoride, and dissolved salts
- Bacteria and viruses
Carbon filters improve water. Membranes purify it. That distinction is why RO remains the benchmark for home drinking water, and it is the reason our RO units carry NSF/ANSI Standard 58 certification for TDS reduction, the independent standard written specifically for reverse osmosis systems.
The five stages in the included system
Every Standard and XL system comes with a five stage RO at the kitchen sink. The stages, in order:
- Sediment prefilter: a 5 micron screen catches suspended grit before anything else.
- Carbon block: absorbs chlorine byproducts like chloramine, THMs, and TCE, which also protects the membrane behind it.
- The RO membrane: the 95 to 99 percent rejection step described above.
- Carbon polish: removes dissolved gases and any lingering taste on the way out of the storage tank.
- Alkaline remineralizer: more on this below.
Water is stored in a small pressurized tank with a food grade bladder, which is why this configuration needs no electricity at all and keeps producing during an outage. For pre 1980 LA homes without an outlet under the sink, that is not a small detail.
Why the alkaline stage matters
Pure RO water is almost distilled. With the minerals gone it tastes flat, and its pH drifts slightly acidic. The remineralizing stage adds back a measured dose of healthy minerals, which balances the pH and gives the water the crisp, slightly sweet taste people associate with expensive bottled brands. You get laboratory clean water that still tastes like water.
The upgrade: seven stage tankless
If you want the best drinking water we install, the tankless HW800 AlkaPro is a $400 upgrade on any system. It adds a second carbon block before the membrane and a final carbon pass after the alkaline stage, seven stages in total, and it throws away the storage tank entirely: purified water is made on demand as you pour.
| 5 stage, included | 7 stage tankless, +$400 | |
|---|---|---|
| Filtration stages | 5 | 7 |
| Under sink footprint | Unit plus storage tank | About 15" by 6", no tank |
| Water on demand | Drawn from the tank | Made fresh as you pour |
| Capacity | Limited by tank size | 800 gallons per day |
| During a power outage | Keeps working | Pauses, needs electricity |
| Membrane flushing | Manual | Automatic |
| Needs an outlet under the sink | No | Yes |
Honest guidance: the five stage system is the right call for most LA kitchens, and it is what we include. Take the tankless if your cabinet is tight, your household drinks a lot of water, or you simply want the best available. Both are certified, and both taste worlds better than the tap.
The waste ratio, honestly
Every RO system sends some water down the drain; that is how the membrane rinses rejected contaminants away. Older systems wasted three or four gallons per purified gallon. The tankless AlkaPro runs a 2:1 ratio, two cups of purified water for every one cup drained, among the most efficient designs sold. The tank system is less efficient than that, which is a real trade for the outage resilience and the lower price. We would rather you hear it from us.
What it costs to own
The five stage RO is included with the Standard System at $2,999 and the XL, with a dedicated faucet in your choice of five finishes. The seven stage tankless is a $400 upgrade. Either way the filters change once a year, $199 including parts and labor, and the membrane path is lead free to NSF 372 standards. That is the entire ownership story.