A shower filter sits between your shower arm and your showerhead. Water passes through it before it reaches your skin. Inside the housing is a cartridge filled with different filter media. Each media type does a different job. Together, they reduce chlorine, sediment, and heavy metals. They also make the water feel better on your skin and hair.
The POWERBOX™ shower head filter for hard water uses several stages of filtration in sequence.
What’s inside a shower filter cartridge?
The cartridge does the actual filtering. You replace it every 2 to 6 months. Inside it, water moves through layers of filtration media in a fixed order. Each layer has a specific role.
Here are the main media types in the POWERBOX™ cartridge:
PP Cotton and Stainless Steel Mesh
These come first. They catch rust particles, sand, sediment, and other debris from the pipes. They work as a pre-filter. They also protect the other media from clogging too quickly.
KDF-55
KDF-55 is a zinc-copper alloy. When water touches it, an electrochemical reaction takes place. That reaction converts free chlorine into harmless chloride. KDF-55 also helps reduce some heavy metals, including lead and mercury. It works well at moderate temperatures. Above 40°C, it works less well. That is why calcium sulfite is also in the cartridge.
Calcium Sulfite
Calcium sulfite is very effective at reducing chlorine in hot water. The reaction is fast. It happens almost instantly as water passes through. At 40°C or above, calcium sulfite does most of the chlorine reduction work. KDF-55 and calcium sulfite together cover a wider temperature range.
Activated Carbon
Activated carbon improves the smell and taste of water. It reduces volatile organic compounds (VOCs). These are chemicals that can off-gas in shower steam. It also picks up any leftover chlorine that the other media did not catch. Activated carbon works through adsorption. Contaminants stick to the carbon surface as water flows past.
Mineral and Ceramic Media
These stages help balance pH and soften how the water feels. Hard water has a lot of dissolved calcium and magnesium. A shower filter is not built to remove those minerals completely. But the mineral and ceramic layers reduce the harsh feel. The water feels gentler on skin and hair.
What does a shower filter actually remove?
A shower filter reduces certain contaminants. It does not purify water to drinking standard. It also does not remove all dissolved minerals.
Here is the simple breakdown:
It reduces:
- Free chlorine, the main disinfectant in Australian tap water
- Some heavy metals, like lead, mercury, and copper, with partial reduction
- Sediment, rust, and sand particles
- VOCs and some chemicals that affect smell
- Water harshness to a degree, which can change how skin and hair feel
It does not fully remove:
- Dissolved calcium and magnesium, which are the minerals that cause hard water. A whole-house softener handles those.
- Chloramines, which some Australian cities use. Chloramine reduction is lower than free chlorine reduction.
- Bacteria or viruses. A shower filter is not a disinfection device.
To understand how different filter setups perform, read our guide on single vs multi-stage filters. It explains what each setup can and cannot do.
Why multiple stages?
More stages does not always mean more filter types. With the POWERBOX™ filter, it means multiple layers of each media. KDF-55 appears in several layers, not just one. The same goes for calcium sulfite and activated carbon.
Layering gives the water more contact time. Water moves through a shower filter quickly, especially under high pressure. One thin layer does not give enough time to work properly. Multiple layers extend contact time without slowing the flow too much.
What does the water look like afterwards?
You will not see a visible difference. Filtered shower water looks the same as unfiltered water. It simply has fewer irritants. It feels different on the skin. Many users notice less dryness and less scalp irritation after switching. But results vary. Water chemistry changes from city to city and suburb to suburb.
The cartridge lasts 2 to 6 months in most homes. It depends on your water hardness and how many people use the shower. Read more about how long the cartridge lasts.
Ready to try it?
The POWERBOX™ shower filter comes with two cartridges. Want to know how to install a shower filter? It takes about five minutes and needs no tools.
Frequently asked questions
How does a shower filter work?
A shower filter sits between your shower arm and showerhead. Water passes through a cartridge packed with filter media, including KDF-55, calcium sulfite, activated carbon, and PP cotton. Each layer targets different contaminants. Together, they reduce chlorine, heavy metals, sediment, and VOCs before the water reaches your skin.
What does a shower filter remove?
A shower filter reduces free chlorine, some heavy metals like lead and copper, sediment, rust, and VOCs. It does not fully remove dissolved calcium and magnesium, which are the minerals that make water hard. It also does not fully remove chloramines or bacteria. It is designed to improve water feel, not to purify water to drinking standard.
Does a shower filter work for hard water?
A shower filter reduces the harsh feel of hard water through mineral and ceramic media that can soften the water feel. It does not fully remove dissolved calcium and magnesium. That needs a whole-house softener. But many users with hard water notice better skin and hair feel after using one.
How many stages does a good shower filter need?
More stages mean more layers of each media type, which gives the water more contact time with the filter. The POWERBOX™ uses multiple stages. This gives KDF-55, calcium sulfite, and activated carbon enough contact time to work well, even at higher water pressure.
Does KDF or calcium sulfite work better for hot showers?
Calcium sulfite works better in hot water. KDF-55 is less effective above 40°C. A good shower filter uses both. KDF-55 handles cooler temperatures. Calcium sulfite handles the hot range. This is why multi-media filters work better than single-media ones for shower use.