There’s a gross, oily film in my drinking water!

What’s going on with my tap water?

If you’ve noticed a weird, iridescent film on the surface of your drinking water, you’re probably a little concerned. Not to worry! There’s a good chance the film isn’t harmful to your health at all, but determining whether it’s a risk or nuisance depends on a few things.

Likely culprits for the sources of oily tap water

If you’re on well water, chances are that rainbow sheen can be traced to harmless organic sources. Decaying organic plant matter in your well is one of the most common causes, resulting in the presence of hydrogen sulfide. Another common source happens when iron deposits in minerals dissolve your well water in the presence of iron bacteria. Neither cause is typically harmful to your health, but should be addressed by professionals.

If you’re on city water, on the other hand, there might be cause for greater concern. In that case, there’s a possibility that it might be caused by potentially dangerous, manmade pollutants. These issues need to be remediated immediately.

Will it make me sick?

In most cases, especially if you’re on well water, the film is more of an annoyance than a health risk. In a smaller percentage of instances, there is a risk of contamination. Either way, you’ll want to determine the source of the oily film, and decide if it’s worth taking steps to remediate it. You can schedule a free in-home water test to learn more about your water.

• Determine where your water comes from. If it’s well water, the sheen is likely due to relatively harmless natural sources. If it’s city water, the likelihood of dangerous pollutants is greater. Check out list of known Chicago suburban contaminants to learn more.
• Stir the water. Fill your sink or tub, and stir the water. If the film breaks into platelets, the cause is probably natural. If it quickly forms back together into a uniform slick, oil pollution is the likely culprit.
• Smell the water. If you get a rotten egg smell, you’re probably dealing with an organic or natural cause. If, however, you smell gasoline or diesel, you should be concerned. This means there is petroleum contamination which needs to be addressed immediately.