What Material are the Bypass Valve and Valve Head Made of? January 31, 2025 16:30 Updated They are made of a plastic called Celcon and both products are NSF stamped. Bypass Valve: Valve Head: Related articles How Much Resin Should be in the Tank? Welcome to the Whirlpool Water Softener Family Should there be salt in the Brinewell tube? How to Test for Hard or Soft Water Installing the Tank Light