The formula to convert pressure in psig to inches of water column (in H2O) is:

```

in H2O = psig × 27.71

```

Therefore, to convert 0.5 psig to in H2O, we use the formula as follows:

```

in H2O = 0.5 psig × 27.71 = 13.86 in H2O

```

Therefore, 0.5 psig is equal to 13.86 inches of water column.