Mold Water Hardness & Quality Report (2026)

Hafren Dyfrdwy supplies water to Mold, Flintshire, Wales. The utility draws from a mixed water source, primarily the River Dee catchment. This includes water from reservoirs like Llyn Tegid and Brianne, as well as groundwater from local Carboniferous Limestone boreholes. Treatment facilities, such as the Glasdir and Tryweryn plants, process this water before it reaches approximately 150,000 customers across parts of Denbighshire and Flintshire. The extensive network ensures compliance with stringent UK drinking water standards.

The watershed spans the upper River Dee and Clwydian Hills, where water filters through Carboniferous Limestone and sandstone aquifers. These geological formations are responsible for the water's mineral content. The naturally occurring karstic limestone systems in northeast Wales dissolve significant amounts of calcium and magnesium. This bedrock interaction results in a slightly hard water character, although surface runoff from peaty moors can introduce organic matter that is addressed during treatment.

This slightly hard water can lead to minor limescale buildup over time, affecting appliances like kettles and showerheads. Hot water systems and boilers may benefit from occasional descaling to maintain optimal efficiency. Homeowners can tackle stubborn deposits by regularly cleaning affected items with vinegar or citric acid. While a water softener isn't usually required for slightly hard water, some households might consider one if they experience persistent limescale issues or have specific preferences. The water quality, with a typical pH around 7.5-8.0, meets Drinking Water Inspectorate standards, and Hafren Dyfrdwy actively manages potential taste and odor issues from algae.