Purewell PW-OB-CF Countertop Gravity Water Filter: stages, specs and care

The Purewell PW-OB-CF is a countertop gravity water filter in a 304 stainless steel housing. It holds 2.25 gallons, needs no electricity or plumbing, and comes with four filter elements, a metal spigot with a water-level display and a stand. Here is what its specs mean and what to think about before choosing one.

How a gravity filter works

The system has two chambers. You pour tap water into the upper container, and gravity pulls it through the filter elements into the lower container, where the filtered water waits for the spigot. No pump or power is involved, so Purewell says it can be used indoors or outdoors.

One practical note from the brand: when the lower container is full of filtered water, don't add more tap water to the upper one, or it will overflow. Add water only when there is room below.

The eight stages

Purewell describes the filtration as eight stages, spread across two types of element, two of each in the pack.

• The carbon filters (black) combine a 0.01 micron hollow fibre ultrafiltration membrane, a silver ion membrane and an activated carbon block. Purewell says they reduce rust, sediment, organic matter and heavy metals.
• The fluoride filters (white) combine a fluoride reduction membrane, an activated carbon block and three polypropylene sediment layers, aimed at fluoride and chlorine.

A micron is a millionth of a metre, so 0.01 micron describes a very fine membrane. Activated carbon is generally used to reduce chlorine, taste and odour.

Fluoride and certification

Purewell says its fluoride element removes 90% of fluoride and that it uses a material other than the activated alumina found in some filters. The listing also states that the system has passed NSF/ANSI 42 certification. That standard generally covers aesthetic effects such as chlorine, taste and odour; check the certification documents for exactly what is covered for each element.

One more point from the brand: the filter elements do not lower TDS (total dissolved solids), so a TDS meter reading will not drop much after filtering.

Filter life and replacement

Purewell says the two fluoride filters can filter up to 1,000 gallons, and the two carbon filters up to 6,000 gallons, depending on water quality. For best results it recommends replacing the elements every six months. Harder or more heavily contaminated water typically shortens life, and slow flow is a common sign that elements need attention.

Housing and accessories

The body is 304 food-grade stainless steel, a common choice for kitchenware because it resists rust and cleans easily. The metal spigot has a water level indicator and is said to fit the chamber without leaking. A non-slip stand is included. Overall size is about 8.8 x 8.8 x 20.0 inches (roughly 22 x 22 x 51 cm) and the weight is 9.7 lb (about 4.4 kg), so you'll need clear counter space and some height.

Who it suits

It suits households that want filtered drinking water without installing anything: renters, small kitchens, offices, caravans and places where the power is unreliable. It also appeals to anyone who prefers a stainless steel container over plastic jugs.

What to check before you buy

• Counter space and height: it's tall, so check clearance under cupboards.
• Daily volume: 2.25 gallons is the capacity, and gravity filtration is gradual, so consider how much water you drink and cook with.
• What you want filtered: confirm the certification and listed reductions cover your concerns, and check your local water report.
• Replacement elements: note how often they need replacing and that they're specific to this model.
• First use: follow the manual for flushing and priming new elements before the first batch.
• Cleaning: check how the manual advises washing the containers and spigot.

The short version

• A 2.25-gallon countertop gravity water filter, model PW-OB-CF, in 304 stainless steel.
• Eight stages across two black carbon and two white fluoride elements.
• Rated by Purewell at 90% fluoride reduction; NSF/ANSI 42 certification is listed.
• Needs no electricity; elements should be replaced about every six months.
• Includes a metal spigot with water level display and a non-slip stand; it does not lower TDS.

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