Ground water has the following advantages except –
Ground water is hard, but it is a disadvantage (not advantage).
Ground water

Ground water is the cheapest and most practical means of providing water to small quantities.
Ground water is superior to surface water, because the ground itself provides an effective filtering medium.

Advantages

It is likely to be free from pathogenic agents.
Requires no treatment (disinfection).
The supply is likely to be certain even during dry season.
It is less subject to contamination than surface water.

Disadvantages

It is high in mineral content e.g., salts and magnesium which render the water hard.
It requires pumping or some arrangement to lift the water.
Likely to be free from pathogenic organisms
Usually requires no treatment
Supply is likely to be certain even during dry season
Likely to be hard