Ultraviolet purification
A lamp stage that disrupts the DNA of micro-organisms so they can’t reproduce. It only works in already-clear water, which is why it goes behind the filtration stages rather than instead of them.
The system
The QWS Flex 4V.1
A four-cartridge point-of-entry filtration system, built in Waukesha, Wisconsin, and fitted where the water comes into your house so every tap is treated. Ultraviolet purification and leak monitoring can be added where a water test calls for them.
Four stages
What’s in the housing
Four 20″ Big Blue cartridges in a steel frame, plumbed inline where the supply enters. Nothing proprietary, nothing to plug in.
1
DGD-5005 — general sediment
A dual-gradient depth filter. Coarse grit is caught at the surface and finer particles deeper in, so it holds far more before it clogs than a single-density filter would.
2
GAC-20BB — granular activated carbon
Reduces free chlorine, chloramine and the organic compounds behind bad taste and smell. Carbon is the most absorbent material known.
3
RFFE-20BB — polyphosphate media
Sequesters calcium, magnesium, iron and manganese so they can’t bond and form scale or rust deposits in your pipes and appliances.
4
FloPlus 20BB — 0.5-micron cyst
A carbon block built for high flow at low pressure drop. The finest stage, catching what the first three left behind.
Each cylinder is replaced on its own schedule — you change what’s worn out, not the whole unit. The housing takes standard 20″ Big Blue cartridges, so replacements are widely available rather than proprietary.
Options
What can be added
Only where a water test justifies it. We don’t sell you up on a maybe.
Leak detection and alerts
Fits any of our systems. Real-time monitoring with alerts to your phone, water usage and flow statistics, freeze and drip warnings, and remote whole-home shut-off on the control version.
Contaminant-specific cartridges
Where a test shows something the standard four stages don’t address — heavy metals, high iron, well water with its own character — the cartridge changes to suit.
Certification
What is certified, by whom, and to what
We name the standard and the model behind every claim, so you can check it rather than trust it.
| Standard | What it certifies | Status |
|---|---|---|
| NSF/ANSI/CAN 61 2022 edition |
Drinking water system components — health effects. Sets minimum health requirements for contaminants that could be imparted into your water by the product itself. Certified for cold water, 23 °C. | Certified WQA Gold Seal, 1 August 2023 |
| NSF/ANSI/CAN 372 2020 edition |
Drinking water system components — lead content. Every wetted part is certified lead-free. Meets the California Health & Safety Code §116875 definition of “lead free” (AB 1953) and Vermont’s lead in consumer products law. | Certified WQA Gold Seal, 1 August 2023 |
| NSF/ANSI 53 | Contaminant reduction — the standard covering lead and cyst reduction. It applies to a specific cartridge, not to a system as a whole. | Certification is held per cartridge — ask us for the one your water needs |
| NSF/ANSI 55 | Ultraviolet treatment — Class A disinfection or Class B supplemental. | Applies to the optional UV stage — ask us for the listing |
How to read a water filter certificate
NSF/ANSI 61 and 372 certify what a system is made of — that it is safe and adds no lead. They are not performance ratings, and the NSF 61 certificate says so in its own words: products certified to it “have not been tested or evaluated for contaminant reduction performance. Contaminant reduction testing and certification claims shall be evaluated via the industry’s residential drinking water treatment standards.”
What a system removes is certified separately — under NSF/ANSI 42 for aesthetic effects, 53 for health effects, or 55 for ultraviolet — and those apply to particular cartridges and configurations.
So if a company tells you a whole-house system is “NSF certified” without naming a number, that isn’t an answer. Ask which standard, for which model, and ask to see it. Ours is above, and we’ll hand you a copy.
Specifications
QWS Flex 4V.1
Configuration
Four cartridges, point of entry
Cartridges plumbed inline
Accepts 20″ Big Blue cartridges
Corrosion-resistant housing
Performance
Up to 8 gallons per minute
Up to 12,000 gallons per day
No waste stream
Filters changed annually
Installation & warranty
Fitted where water enters the house
About two hours
No additional internal plumbing
10-year warranty on the housing
Certification & origin
WQA Gold Seal
NSF/ANSI 61 and NSF/ANSI 372
Qualified Water Systems
Waukesha, Wisconsin
Pricing
What it costs
From
$3,850
QWS Flex 4V.1, fitted
What that covers
- The QWS Flex 4V.1 — all four cartridges, plumbed inline
- Standard installation — about two hours, fitted where the water enters the house, with no additional internal plumbing
- Your first year of cartridges
- The in-home water test that decides which cartridges your water needs
What can add to it
- Work beyond a standard install — rerouting pipework, adding a 120 V outlet, awkward or tight access, or a well pressure tank that needs attention
- Ultraviolet purification or leak monitoring, quoted separately and only where the water test calls for them
- Cartridge sets after the first year. The set after the included year is 20% off.
We test your water and look at the space before quoting anything. If your house needs more than a standard install, you get the figure in writing first — no work starts before you have seen it. That is why the price reads “from” rather than a flat number.
Ready to find out what your water needs?
The water test is free and it decides the cartridges — so the quote comes after it, not before. If this isn’t the right system for your house, we’ll tell you.
(414) 710-0106