Alkaline Water and Under-Sink Filters: What You Need to Know

Some under-sink water filters include a remineralisation stage that raises the pH of filtered water — producing what’s commonly called alkaline water. Here’s what that means in practice.

See our full Under Sink Water Filters Guide or our Reverse Osmosis Water Filters Guide.

How Under-Sink Filters Produce Alkaline Water

Standard under-sink carbon filters don’t change the pH of water significantly. RO systems actually lower pH slightly (RO-filtered water is mildly acidic because it removes dissolved minerals). To produce alkaline water from an under-sink system, a remineralisation stage is added after the RO membrane — this passes water through mineral media (typically calcium, magnesium, and potassium) that raises the pH to approximately 7.5–8.5 and adds beneficial minerals back into the water.

Our RO systems with alkaline remineralisation combine RO-level contaminant removal with a final remineralisation stage for a balanced, slightly alkaline result.

What Alkaline Water Actually Does

Alkaline water (pH 7.5–8.5) tastes smoother and less flat than standard filtered water — this is the most consistently reported benefit. The added minerals (calcium, magnesium) are genuinely beneficial nutrients. Claims about alkaline water “boosting immunity”, “curing disease”, or providing dramatic health transformations are not supported by clinical evidence — be sceptical of any product making these claims.

Simpler Alternatives for Alkaline Water

You don’t need an under-sink system to get alkaline water. Our benchtop water coolers with Maifan stones and Prill Beads in the 8-stage KDF cartridge naturally raise the pH of filtered water. This is a simpler and more affordable approach for most households. See our Benchtop Water Filters Guide.

Frequently Asked Questions