The two chemicals allowed to be used in antifreeze systems connected to public water supplies are

The two chemicals allowed to be used in antifreeze systems connected to public water supplies are

• A. Ethylene glycol and methanol
• B. Propylene glycol and glycerin
• C. Propylene glycol and ethylene glycol
• D. Propylene glycol and glycerin

Answer: (D)

When antifreeze is used in systems that connect to public drinking water, safety depends on using a substance that won’t contaminate the water if a leak occurs. Ethylene glycol and methanol are highly toxic and pose serious poisoning risks, so they are not allowed in potable-water loops. Non-toxic options are required, and propylene glycol fits this need because it has low toxicity and is widely approved for contact with drinking water. Glycerin (glycerol) is also non-toxic and compatible with water, making it acceptable in these systems. Together, propylene glycol and glycerin meet the safety and compatibility requirements for antifreeze in public-water-connected systems, which is why this pairing is permitted.

When antifreeze is used in systems that connect to public drinking water, safety depends on using a substance that won’t contaminate the water if a leak occurs. Ethylene glycol and methanol are highly toxic and pose serious poisoning risks, so they are not allowed in potable-water loops. Non-toxic options are required, and propylene glycol fits this need because it has low toxicity and is widely approved for contact with drinking water. Glycerin (glycerol) is also non-toxic and compatible with water, making it acceptable in these systems. Together, propylene glycol and glycerin meet the safety and compatibility requirements for antifreeze in public-water-connected systems, which is why this pairing is permitted.