With NSF 61 approval for use in potable water systems, Loctite® products can be used to ensure the proper operation of fasteners, fittings & flanges. Here are some Loctite® branded products with NSF 61 Approval:

Threadlockers
  »  Loctite® 242® Threadlocker, Medium Strength
  »  Loctite® 243™ Threadlocker, Medium Strength/Oil Resistant
  »  Loctite® QuickStix™ 248™ Threadlocker, Medium Strength/Removable
  »  Loctite® 290™ Threadlocker, Wicking Grade
 
Gasketing
  »  Loctite® 518™ Gasket Eliminator® Flange Sealant
 
Thread Sealing
  »  Loctite® QuickStix™ 561™ PST® Pipe Sealant
  »  Loctite® 564™ Thread Sealant, General Purpose
  »  Loctite® 565™ PST® Thread Sealant, Controlled Strength
  »  Loctite® PST® 567™ Pipe Sealant
  »  Loctite® 55™ Pipe Sealing Cord
 
Retaining
  »  Loctite® 680™ Retaining Compound, Slip Fit/High Strength
 
Other Products
  »  Loctite® 7649™ Primer N™
  »  Loctite® Nordbak® Brushable Ceramic
  »  Loctite® Fixmaster® Wet Surface Repair Putty