Safe is a floor, not a target
Municipal water in the United States is regulated to a legal standard. That standard is a floor — the point below which water is considered unsafe to distribute. It is not a description of good water. A utility that meets every limit exactly has done its job and still hands you something you would not choose if you had a choice.
Two things follow from that. First, "it passed testing" and "it tastes and behaves the way you want" are unrelated claims. Second, the last stretch of the journey — the service line between the main and your tap — is not the utility's to control, and in most of the country nobody has surveyed it.
What gets added on purpose
Chlorine and chloramine are disinfectants. They are in your water deliberately, because the alternative is waterborne disease, and that trade is not close. They also account for most of what people mean when they say tap water "tastes like a pool." Carbon filtration removes them readily — this is the single most noticeable change most people experience.
Fluoride is added by many systems. Whether you want it is a genuine personal decision. Carbon alone will not remove it; reverse osmosis will.
What arrives by accident
- Lead — almost never from the treatment plant, almost always from the pipe, solder, or fixture between there and you.
- PFAS — the "forever chemicals," industrial in origin, increasingly regulated and widely present.
- Sediment and rust — particulates picked up in distribution, worst after main work or a pressure change.
- Microplastics — abundant, poorly characterised, and reduced by fine filtration.
- Nitrates — agricultural runoff, concentrated in farming regions and in well water.
Filtration is the only part of this chain you control. Everything upstream of your counter was decided for you.
The part nobody mentions: filtration also removes the good things
This is the honest complication in the water business, and most brands skip it. Filtration is not selective. A reverse osmosis membrane rejects contaminants by size and charge, and calcium, magnesium and potassium are small and charged. RO water is genuinely clean and genuinely empty. People describe it as flat, and they are describing something real: the minerals that give water its structure and taste are gone along with everything else.
That is why every serious RO setup ends with a remineralizing stage, and why we sell mineral drops at all. Take it out, then put it back. A brand that only sells you the first half is selling you half the answer.
How far upstream to treat
This is the only real decision, and it is a plumbing decision more than a water one. Point of entry means the main line, before the house branches. It is the only approach that stops scale reaching your appliances — and it is a five-figure job on an older house, needs a plumber, and treats a great deal of water you will never drink. We do not sell one.
Point of use means one tap. An under-sink system treats the water you drink and cook with and ignores the rest, which is most of the benefit for a fraction of the work. A countertop unit treats a jug at a time and needs no installation at all, which makes it the only option if you rent.
Most people over-buy at the point of entry and under-buy at the tap. If you can only do one, do the tap you drink from — it is the water that ends up inside you, and it is the cheapest to fix.
What we would actually do
- Find out what is in your water. Your utility publishes an annual report; your state or county will send it free.
- Filter for what is actually there. Carbon handles taste, chlorine and many organics. Reverse osmosis handles dissolved solids, fluoride and nitrates.
- Put the minerals back if you fitted reverse osmosis — either through a remineralizing stage or a few drops in the jug. Skip it if you did not.
- Change the cartridge on schedule. An exhausted filter is worse than no filter, because you stop paying attention.