How Does an Alkaline Water Filter Work?

An alkaline water filter does two things: it filters contaminants from your water, and it raises the water’s pH to a mildly alkaline level (typically pH 8–9). Here’s how it works.

Browse our benchtop alkaline water purifier or see our Benchtop Water Filters Guide.

The Filtration Stages

A quality alkaline water filter uses multiple stages, each targeting different contaminants or water properties:

1. Sediment stage — removes sand, silt, rust, and particles
2. KDF media — removes heavy metals (lead, mercury, copper) and reduces chlorine through a redox reaction
3. Activated carbon — removes chlorine, chloramines, VOCs, and taste/odour compounds
4. Ceramic stage — removes bacteria and fine particles
5. Mineral stone stage (maifan stone, far infrared balls) — releases beneficial minerals (calcium, magnesium, zinc) and raises pH
6. Alkaline/remineralisation stage — adds alkaline minerals to raise pH to 8–9

Our 8-stage alkaline water purifier uses all of these stages in sequence.

How pH Is Raised

The alkaline effect comes from the mineral stone and remineralisation stages. As water passes through, calcium, magnesium, and other alkaline minerals dissolve into the water, raising its pH from neutral (pH 7) to mildly alkaline (pH 8–9). This is the same process that occurs naturally when water flows over mineral-rich rock formations.

What the Evidence Says

The filtration benefits of an alkaline water filter — chlorine removal, heavy metal reduction, improved taste — are well established. The specific health claims around alkaline water (anti-ageing, cancer prevention, acid reflux relief) are more contested. Some small studies show benefits for specific conditions; larger clinical evidence is limited.

What’s clear: filtered water with a balanced mineral profile tastes better and is better for you than unfiltered chlorinated tap water. Whether the alkaline pH itself provides additional benefits beyond the filtration is a matter of ongoing research.

Frequently Asked Questions