Whole-house reverse osmosis, and when a smaller system serves better

Advertised prices, verified

Deciding whether whole-house RO is your case

1. Confirm the contaminant needs a membrane. RO earns its complexity when a test finds dissolved contaminants that carbon and specialty media handle poorly at your levels, high total dissolved solids among them. If your report reads chlorine, taste and scale, cheaper stages fix those.
2. Ask whether one tap would do. If the concern is drinking and cooking water, an under-sink RO unit treats the tap you drink from at a fraction of the cost, and most brands in the index sell exactly that. Whole-house RO is for when skin contact or every outlet genuinely matters.
3. Plan for storage, pressure and reject water. Membranes work slowly, so whole-home RO needs an atmospheric storage tank and a repressurization pump, plus pre-filtration to protect the membranes, and it sends a reject stream to drain. Space and plumbing for all of that is part of the real price.
4. Get the water re-mineralized where it matters. RO water is aggressive toward metal plumbing and flat-tasting; whole-home systems usually add a calcite or blending stage on the outlet. It is a standard part of a competent design, and the product pages linked above show which brands include it.

Whole-house RO against the alternatives

For most city-water homes the honest chain is a whole-house carbon system for chlorine and taste, a softener or conditioner for scale, and an under-sink RO for the drinking tap; each stage is in this index with verified prices, and together they usually cost far less than membrane-treating every gallon. Whole-home RO is the specialist answer for water that fails at the dissolved-solids level, common on some wells and rare on municipal supplies.

The verified figures in the table are the brands' advertised prices for their named RO systems, from under-sink units to whole-house membranes where the brand publishes one. As always in this index, a brand with no published price is recorded as exactly that; whole-house RO in particular is often engineered per home and quoted rather than listed, and the honest comparison starts from the numbers the brands are willing to print.

Common questions

Is a whole house reverse osmosis system overkill?

On typical municipal water, usually yes: carbon, softening and an under-sink RO cover the real problems for far less money and plumbing. On water with high dissolved solids or specific membrane-level contaminants confirmed by a test, whole-home RO is the right tool.

What does whole-house RO need besides the membranes?

Pre-filtration to protect the membranes, an atmospheric storage tank, a delivery pump to restore pressure, a drain for the reject stream, and usually a re-mineralizing stage on the outlet. The system price is only part of the installed reality.

How is under-sink RO different?

Same membrane technology, one tap: it treats drinking and cooking water at the kitchen sink with a small tank and no whole-home plumbing. For most buyers researching whole-house RO, it is the system they actually need, at the prices shown in the table.

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