Waterway 1/4″ Plug with O-Ring, 873-E15S1

This is the Waterway 873-E15S1, a 1/4 inch plug supplied with its O-ring. Waterway lists it for the SmartClean sand and Crystal Water DE multiport valve assemblies in both 1-1/2 inch and 2 inch sizes.

Where it goes

This is the small 1/4 inch port plug on the valve body rather than one of the main plumbing connections. Small as it is, it is a common source of a slow drip that gets blamed on the valve itself, because the O-ring hardens and takes a set long before anything else on the multiport wears out.

Fitting

Because the O-ring comes with the plug, the whole seal is renewed in one go. Thread it in and take it up snug so the O-ring compresses, then stop. The seal comes from the O-ring, not from torque, and leaning on a plastic plug is the usual way to crack the boss it threads into.