Fill in the blank: my water smells like_____________. Hopefully you answered "nothing," or maybe "chlorine."
A quick Google search yielded some far more interesting results:
Unfortunately, most contaminantsgive no off-putting scent or taste to your water. (Wouldn't it be more convenient if we could taste lead in our water? Then we'd know we had a problem!) If you do smell something in your water, though, you might have a problem.
So what does your water smell like? If you answered:
Rotten eggs or sewage. You likely have sulfur in your water. The presence of sulphur, or rather hydrogen sulfide, in even the smallest amount can make your water smell like sewage and can negatively affect taste. Small concentrations of hydrogen sulfide in your water usually pose no health risks. However, higher concentrations can cause nausea and illness.
Gasoline. You might have sulfur or iron bacteria in your water, neither of which poses a health threat. The more worrisome problem would be VOCs in your water. VOCs are a group of common industrial and household chemicals and are emitted by gasoline, fuel oil, paint strippers, and thousands of other products. Some VOCs are quite toxic, while others pose very little risk.
Bleach. You're smelling the chlorine your public utility uses to disinfect your water. A simple water filter will remove up to 99% of this stuff, ensuring that you have clean water that doesn't taste like a swimming pool.
Garlic. Once again, sulphur bacteria is your likely culprit.
Fish or dirt. A fishy or earthy smell in your tap water is probably the result of algae growth in the water reservoir that supplies your public utility. Any filter that removes or reduces VOCs will help keep your water from smelling like a fish tank.
Metal. Copper piping, magnesium in your water source, and iron piping can all make your water smell like metal. You're more likely to notice this smell if you live an an older house. You might also consider that the metallic smell is coming from the anode in your hot water heater. (The purpose of this thing is to prevent corrosion in your hot water pipes, since most corrosion is increased by heat. What happens is that the water literally eats this thing up so that it won't eat your pipes up.)
As you can see, many different factors can contribute to your water's smelling less than appealing. Ultimately, you solution will depend on what's causing your water to smell-which means water testing and sufficient water filters or water treatment systems if necessary-particularly if you get your water from a well and not a municipal water supply.