Yes: reverse osmosis water is safe and healthy to drink. An RO membrane removes dissolved solids, lead, arsenic, nitrates, PFAS and disinfection byproducts from the water at your kitchen tap. It also removes most of the calcium and magnesium, which changes the taste more than it changes your nutrition, because tap water supplies only a small fraction of the minerals in a normal diet. If you prefer the taste of mineral water, a remineralization stage puts a measured amount back.
That is the short version. The longer version matters, because the internet is split between health blogs calling RO water "dead" and dealer pages calling it the only safe thing to drink. Neither is right. Here is how we explain it at kitchen tables from Spicewood to Cedar Park, using the actual numbers from local water quality reports.
What reverse osmosis actually removes
An RO system pushes water through a semi-permeable membrane with pores so small that most dissolved ions cannot pass. Whatever the membrane rejects goes to the drain. A well-made residential system (look for one tested to the NSF/ANSI 58 standard) removes:
- Total dissolved solids (TDS), typically 90 to 98 percent. Cedar Park tap water runs about 286 mg/L TDS; Austin Water finished water is around 200. RO product water usually reads under 20.
- Lead and copper that dissolve from plumbing after the treatment plant. Cedar Park's 2023 sampling found one tap over the copper action level.
- Arsenic, nitrates, fluoride and sodium, the ions a carbon filter leaves untouched.
- Radium and other radionuclides, a genuine concern on Trinity aquifer wells in the Hill Country.
- PFAS, where RO outperforms standard carbon by a wide margin.
- Disinfection byproducts such as trihalomethanes (TTHMs), which form when chlorine or chloramine reacts with organic matter in lake water.
Two honest limits. First, RO is point-of-use: it treats the drinking-water faucet and usually the refrigerator line, not the shower or the washing machine. Second, the membrane does not remove dissolved gases and is not a disinfection step. On a well with a positive coliform test, disinfection comes first and RO second. The carbon pre-filters also do critical work on chlorine and chloramine, because chloramine degrades the membrane if it gets through.
The mineral question, with numbers
This is the part the health blogs get half right. Yes, RO removes most of the calcium and magnesium in your water. No, that does not meaningfully change your nutrition. Look at what is actually in the glass:
- Cedar Park's 2025 water quality report lists calcium at 37.4 mg/L and magnesium at 21.5 mg/L, for 183 mg/L total hardness. Austin Water lime-softens its supply to about 93 mg/L, roughly half that.
- Someone who drinks two liters of Cedar Park tap water a day takes in about 75 mg of calcium and 43 mg of magnesium from it.
- Adult calcium needs run around 1,000 mg a day; magnesium roughly 300 to 400 mg. Tap water, even in a hard-water city, covers well under 10 percent of either. A cup of yogurt or a handful of almonds outweighs it.
The World Health Organization has examined this question in its reviews of demineralized drinking water. The fair summary: there is no strong evidence that low-mineral drinking water harms people eating a normal diet, and the cautions in that literature are aimed at populations already short on minerals from food. If your diet is reasonable, RO water is not going to pull anything from your bones. One point in RO's favor that rarely gets mentioned: if you have a softener, RO also removes the sodium the softener exchanges in, which is welcome for anyone on a low-sodium diet.
Taste, pH and remineralization
Where the minerals do matter is taste. Water with almost no dissolved solids tastes flat to many people; some describe it as "thin." It is also slightly acidic, typically pH 5.5 to 7, because carbon dioxide passes through the membrane while the bicarbonate that would buffer it does not. That is the same chemistry as rainwater, and it is harmless to drink.
If flat water bothers you, a remineralization cartridge (often sold as an "alkaline" stage) after the membrane dissolves a small, controlled dose of calcium and magnesium carbonate back in. It raises pH into the 7 to 8 range and gives the water a rounder taste. Coffee drinkers notice this most: espresso pulled on pure RO water can taste sour and thin, while lightly remineralized water lands close to what specialty-coffee brewing guidelines recommend. RO also ends the cloudy-ice complaint that sends a lot of people looking at drinking-water systems in the first place. Clear ice is a TDS story.
Why Central Texas homes add RO
Almost everyone in our service area drinks treated Lake Travis or Lake Austin water, and it is well-run water. People still add RO for a few specific, local reasons:
Chloramine and its byproducts. Austin Water, Cedar Park, Leander and Liberty Hill all disinfect with chloramine (chlorine plus ammonia), at average residuals of roughly 2.3, 3.09, 2.40 and 1.76 mg/L in their latest reports. Chloramine does not off-gas the way chlorine does, and it reacts with lake-water organics to form TTHMs. Cedar Park's 2024 samples ranged from 38.2 to 97.8 parts per billion, with a highest running annual average of 69.3 against a federal limit of 80; Austin averaged 40.5. Nothing there breaks a rule. It is simply closer to the line than most people expect, and RO with catalytic carbon pre-treatment is the documented residential fix at the tap.
Taste-and-odor events. In February 2019, dead zebra mussels in an Austin Water raw-water main produced 2,451 complaints of tap water that smelled like pond water within days. Lake Travis and Lake Austin have both been infested since 2017, and low-lake summers concentrate algae flavors. An RO system rides through those episodes.
Radium and TDS on Trinity wells. North and west of the lakes, homes on private wells in the Trinity aquifer can carry naturally occurring radium. The City of Liberty Hill's own Trinity wells tested combined radium at 3.8 pCi/L in 2022, which is 76 percent of the federal limit, and private wells in the same formation are not tested unless the owner pays for it. RO is one of the EPA-listed treatments for radium at the tap.
The bottled-water habit. Many families we meet have been buying cases of bottled water for years. An under-sink system that produces the same result for a few cents a gallon is usually the cheaper path within the first year.
If any of these apply to you, start with facts rather than equipment. Our water testing page explains what we check in the home and when a lab test is the right call, and our reverse osmosis drinking water systems page covers how an under-sink system is sized, staged and installed.
When RO is the wrong first move
RO is not the answer to every water complaint, and an honest installer will say so:
- Hard water with no softener. At 10 to 11 grains per gallon (Cedar Park, Leander, Steiner Ranch, Lakeway), calcium scales the membrane and cuts its life sharply. A softener upstream is the right order of operations.
- Iron, sulfur or bacteria on a well. Iron fouls membranes, and bacteria can grow in the storage tank. Treat those at the point of entry first, then add RO for drinking water.
- Your only complaint is chlorine taste. A catalytic carbon filter, whole-house or under-sink, costs less and sends nothing down the drain.
- You want protection at every tap. Showers, laundry and water heaters need a whole-house system. RO is a drinking-water tool.
Water waste, maintenance and cost
Older RO systems sent three to four gallons to the drain for every gallon produced. Modern permeate-pump and high-efficiency designs run near 1:1, which matters in a region that spent 2023 through 2025 under drought restrictions.
Typical costs, from national cost guides rather than our own pricing: an installed under-sink RO system generally runs $300 to $1,500 or more, depending on the number of stages, whether a remineralization cartridge is included and whether a refrigerator line is tied in. Pre-filters and post-filters are changed roughly once a year. The membrane itself typically lasts two to five years, and lasts longer on softened, dechlorinated feed water. An inexpensive handheld TDS meter tells you when the membrane is fading: when product-water TDS climbs past about 10 percent of the tap reading, it is time.
Drinking water in Cedar Park
Cedar Park is the clearest case for kitchen RO in our service area: 183 mg/L hardness, chloramine averaging 3.09 mg/L, and TTHM samples that approached the federal limit in 2024. The good news is that the water is uniform and well-documented, so the right system is predictable: softened feed, catalytic carbon, membrane, and a remineralization stage if you want it. You can read how we approach homes in Buttercup Creek, Twin Creeks and Anderson Mill West on our Cedar Park page.
Absolute Water Solutions has been based in Spicewood and installing water treatment across the Austin area and the Hill Country since 2003, under TCEQ water treatment license WT001370, with every job done by our own crews. We test your water first and recommend only what the test supports. Call (512) 587-8188 during business hours, Monday through Friday, 8am to 5pm, or request a free estimate online.