How much fresher is water that has set in the municipal water supply or the pipes on your property for a few days than water that has set in a reservoir for a few days. If you have no light to promote micro-organisms and no contaminants to foul the water.....
Watering with nipples is the most economical, low-tech, efficient, and low wastage method of watering most animals there is. Some people will prefer other methods. But, that does not change anything in regards to the benefits of nipples.