Silver, Salt, Holy Water Test

As many supernatural creatures. demons and ghosts are vulnerable to silver, salt and/or Holy Water, these substances are used as a test by Hunters to help determine whether someone is human. It is not foolproof - for example it failed to detect that the Adam Milligan was in fact a ghoul disguised as the real Adam.

2.22 All Hell Breaks Loose: Part Two

When Ellen, presumed dead after the Roadhouse was burned down, appears at Bobby's hegets her to drink holy water to confirm that she is not possessed.

2.14 Born Under a Bad Sign

Sam is revealed to be possessed by a demon when Dean splashes him with holy water.

4.01 Lazarus Rising

When Bobby finds a resurrected Dean on his doorstep, he assumes it is a supernatural being and tries to kill him. Dean tries to prove his identity by cutting himself with a silver knife, and they embrace. Bobby then checks whether Dean is possessed by dousing him in holy water.

4.19 Jump The Shark

When Sam and Dean meet Adam who claims to be John Winchester's son, Dean tests Adam with silver and holy water. He doesn't react to them, however he is not human, he is a ghoul.

5.04 The End

When Dean is captured by Future Dean in the year 2014, Future Dean tests Past Dean with Silver, Salt and Holy Water.

5.15 Dead Men Don't Wear Plaid

Bobby tests his resurrected wife Karen with salt, silver, and holy water to try and work out what she is. She doesn't react to any, despite having been resurrected by Death.

6.19 Mommy Dearest

am and Dean find two orphaned boys named Joe and Ryan Silver. Dean says there are "a couple of dozen tests" to make sure they are human. It is unclear which ones dean uses, but he fails to detect that Ryan Silver is a monster of the type Dean has dubbed Jefferson Starships.

7.08 Season Seven, Time for a Wedding!

Becky assures Dean that Sam tested her with silver, salt and holy water before he agreed to marry her.

7.17 The Born-Again Identity

When the hunter/taxidermist Mackey meets Emmanuel, he does the ritual on Emmanuel and tells Dean that he's the real deal.

8.12 As Time Goes By

Sam and Dean test Henry Winchester with holy water and silver.

10.03 Soul Survivor

After turning Dean back from being a demon, Sam tests Dean with holy water.

10.06 Ask Jeeves

Dean and Sam test Olivia with what they think is a silver knife, but it is stainless steel, so she is able to hide that she is a shapeshifter.