Bottled mineral water that has been exposed to improper storage conditions such as exposure to direct sunlight over a period of time may develop the ability to contain chemicals and harmful compounds. These chemicals will influence the quality of the mineral water and over time, the chemicals may cause the bottled mineral water to spoil. If the disinfection process of the water and the bottles are not adequate, the mineral water may also be contaminated with bacteria and germs.

Natural mineral water does contain a number of micro organisms that are not harmful to people. These micro organisms will not multiply in mineral water that is bottled, transported and stored under the correct conditions. 

Bottled mineral water will spoil or go bad if the bottle storing the water has been opened or if the bottle has not been sealed properly or is damaged. This will allow bacteria to come into contact with the mineral water and start growing in the water bottle. It is essentially the unsafe fungal and bacterial growth in the mineral water that can cause harm to people. 

Individuals that purchase large bottles of mineral water to dispense into smaller water bottles as needed should consider these two suggestions. Firstly, one should consume the opened water within at least two weeks after opening the mineral water bottle or as soon as possible thereafter. Secondly, the smaller containers used to keep the mineral water in should be properly washed with warm soapy water before being re-used.

Unopened bottled mineral water can be stored for long periods of time, but the fresh, clear and refreshing water taste may be replaced with a less refreshing, almost stale taste. This does not necessarily mean that the mineral water has gone bad or spoiled, but one is less likely to enjoy and consume water that is not appetising.