Probably the most recognisable symptoms of hard water are soap scum in the tub and shower, and hard water spots on faucets and fixtures. Hardness minerals react with soaps and detergents to form an insoluble, sticky residue that's difficult to rinse from bathtubs, sinks, faucets and fixtures.
The same soap residue is often left on hair, skin and clothing, too. Although not highly visible in these instances, it can cause your skin to dry and itch, and clothing to fade and wear prematurely.
Hard water causes other problems, as well. Over time, scale formed from continuous contact with dissolved minerals in water can collect inside plumbing and on the internal parts of water-using appliances.
Service calls to plumbers and repair persons may become necessary as water pressure drops and mechanical parts stop working.
Hard water scale can also coat the inside of a water heater and drastically reduce its heating efficiency. Greater fuel consumption and higher utility bills result when the appliance has to heat water through a layer of rock.