All bottled water is not created equal, so how do you know whether to go with the spring water or mineral water on a hot day? Making the right choice may involve more thought and consideration than you realize.

According to the International Bottled Water Association, drinking water is sealed in bottles or containers. It is safe and intended for human consumption. Bottled water is also the more expensive option, and all of those non-recycled plastic bottles take a toll on the environment. The Environmental Working Group advises drinking filtered tap water instead. When you opt for bottled water, it is important to understand what you are buying and whether it is the right choice. Here is a brief guide to your different options:

Purified water Water that has been treated to meet the United States Pharmacopeia’s definition of purified water can be labeled as such. Purified water can have any origin, and may be treated through distillation, deionization or reverse osmosis to remove chemicals and microbes. It may be referred to by treatment process, so distilled water is just a variety of purified water.

Spring water Aquifers, or bodies of porous rock through which water can flow, are nature’s purification filters. When overflow from the aquifers reaches the surface, it results in a spring. To qualify as spring water, the water must be collected at the spring or by using a borehole to reach the underground source that contains the same quality or water as the spring does. According to the Environmental Protection Agency, “glacier water” and “mountain water” are not regulated.

Artesian water Also known as artesian well water, this type of bottled water is collected from a confined aquifer, possibly via external force.

Mineral water This kind of bottled water naturally contains 250 or more parts per million of total dissolved solids. It originates from an underground source and no minerals are added.

Sparkling bottled water After it is treated, sparking water contains the same amount of carbon dioxide as it did when it emerged from the source, possibly through carbon dioxide replacement. According to the EPA, sparkling water, carbonated water, soda water, seltzer and tonic water are not regulated as bottled water and are considered soft drinks.

Tap water See the status of your community drinking water by checking online consumer reports or check with your water utility or public works department. The EPA says that most people do not need to treat their home drinking water if it comes from the regulated public water systems. They can opt to take the extra step to improve the taste or protect those who are more susceptible to waterborne diseases. You can invest in a point-of-use (POU) system that treats the water from a specific tap, or a point-of-entry (POE) system that handles the water where the water line enters the house. However, if you have a private well, you should get the water tested yearly. Be aware of potential problem sources, like pollution and disposals, in and around the area of your well.

From an environmental standpoint, the best bottled water may be the one you kind you put in your Klean Kanteen or other eco-friendly water bottle. The EWG suggests going with a brand that is clearly labeled and identifies its means of treatment if you do choose to drink bottled water. Here is its full report.