Karratha Water Hardness & Quality Report (2026)

Karratha's drinking water is supplied by the Water Corporation, drawing from the Millstream Aquifer and Harding Dam (Harding River system) for the City of Karratha LGA Pilbara regional distribution in Western Australia. Water hardness in Karratha is measured at 264 mg/L — classified as hard, substantially exceeding the Australian Drinking Water Guidelines (ADWG) aesthetic guideline of 200 mg/L published by NHMRC. Karratha — a major Pilbara regional city and the commercial hub of WA's resource-rich north-west, known as the gateway to the Burrup Peninsula and the Murujuga rock art precinct, the LNG and gas processing industry of Karratha Gas Plant and WOODSIDE's Burrup facilities, the Karratha City Centre urban renewal project, and the largest regional city in the Pilbara — receives very hard supply from the Millstream Aquifer and Harding Dam system characteristic of remote WA Pilbara regional supplies.

Karratha's elevated hardness reflects the highly mineralised Millstream Aquifer and Harding Dam catchment geology of the Karratha Pilbara regional supply system. The Millstream Aquifer — a carbonate limestone and chert artesian system within the Fortescue Group geological formation of the Pilbara — accumulates very high dissolved calcium, magnesium, and carbonates from the deeply mineralised Pilbara terrain. The Karratha Pilbara regional distribution at 264 mg/L and TDS 784.8 mg/L is consistent with other hard remote WA regional supplies (Newman 266.5 mg/L, Esperance 287 mg/L, Broome 357.5 mg/L), confirming the hard character of remote WA Pilbara regional water supplies.

Karratha residents face significant daily limescale challenges — kettle descaling weekly is standard, shower screens accumulate heavy deposits, and hot water systems require annual inspection. Solar hot water systems in WA's tropical climate benefit from regular servicing. Under WA water restrictions, garden irrigation is limited. The elevated lead reading (0.005 mg/L) warrants always briefly running the cold tap before drinking. The Water Corporation provides water quality information at watercorporation.com.au, with all ADWG health standards met.