Sitting water does grow bacteria although it usually needs to sit for a month or longer.
For example if you have well water and the well sits unused and it is opened to the environment then bacteria can enter the well water and make you sick when you drink it.
However you can shock the well with bleach to kill the bacteria and the well water will then be safe again.
Open bottles of water or glasses of water could also grow bacteria but it's very unlikely for that to happen.
The three problems with bottled water are.
Bottled water companies often draw out the maximum amount of water they want to regardless of water shortage or drought conditions.
Bottled water companies often have an impact on local economies because they pay little money for the water they take.
And bottled water companies harm the environment by depleting the aquifers and groundwater sources.
Most bottled water contains no chlorine although some brands of bottled water may contain around 4.0 mg/l of chlorine.
However tap water contains more chlorine than bottled water that contains chlorine.
Bottled water is better to drink than tap water especially if your tap water contains chlorine and is coming from a city water supply.
However if your tap water is coming from a private water well that is clean and healthy without bacteria then the tap water from the well would be better to drink as it contains more healthy minerals that are needed for optimal health.
But if your tap water is city water with other chemicals such as chlorine then the bottled water would be the better water to drink.
Most filtered water and bottled water does not have any chlorine in it as the chlorine is removed during the filtering and purification process.
Bottled water goes through filtering and other processes that remove chemicals and chlorine from the water before it is bottled.
Some bottled water comes from water wells and other bottled water comes from city water supplies that is filtered before being bottled.