Caloundra Water Hardness & Quality Report (2026)

Caloundra's drinking water is supplied by Unitywater, with bulk water managed by Seqwater from Baroon Pocket Dam on Obi Obi Creek and Lake Macdonald, supplemented during dry periods by Lockyer Valley groundwater to maintain supply security across south-east Queensland. Water hardness in Caloundra is measured at 201.5 mg/L — classified as hard and marginally exceeding the Australian Drinking Water Guidelines (ADWG) aesthetic guideline of 200 mg/L published by NHMRC. Hardness levels vary seasonally depending on the blend ratio between surface water and harder groundwater sources.

Caloundra's elevated hardness reflects the Lockyer Valley groundwater component in the south-east Queensland supply blend. The Lockyer Valley's shallow alluvial aquifers overlie Triassic–Jurassic sedimentary formations containing carbonate-cemented sandstone and gravel, where groundwater dissolves significant calcium bicarbonate. During dry periods, when Seqwater draws more heavily on this groundwater to supplement the Baroon and Lake Macdonald surface storages, hardness at the southern Sunshine Coast tap rises accordingly.

Caloundra residents face significant limescale accumulation on taps, shower screens, and in kettles — descaling every three to four weeks is common during drier months. Solar hot water systems, widely installed across the Sunshine Coast for energy savings, are particularly susceptible to scale build-up inside collector tubes and storage cylinders at this hardness level; annual professional servicing is strongly recommended. Under Queensland water restrictions, limiting outdoor irrigation helps manage supply pressure across the broader south-east Queensland network. A scale inhibitor or whole-house water softener is a practical investment for protecting appliances long-term in the Caloundra area.