Chlorine

A little bit of poison can be a good thing.

This is to kill bugs but hopefully not you too.

Swimming Pools

• Target Free Chlorine Level:
  1.0 to 3.0 parts per million (ppm)
• Ideal for Most Pools:
  2.0 ppm is a good middle target.
• Why:
  Enough to keep the water sanitary but not so much as to cause eye/skin irritation or damage equipment.

Drinking Water (Municipal Tap)

• Target Chlorine Residual:
  0.2 to 0.5 ppm (sometimes up to 1.0 ppm)
• Regulatory Limit (U.S. EPA):
  Maximum allowed is 4.0 ppm

Summary Table:

Too much chlorine can irritate eyes, nose, and skin, and can also create unwanted byproducts (like chloramines or trihalomethanes).
Too little chlorine means water isn’t disinfected and harmful microbes can grow.

Key message:
Use only as much as necessary to stay within recommended target ranges for your specific application!