Another option is an Arcade script in your symbology. The code below is mostly pseudocode, so you'll need to adapt it to your actual field names & the type value for 'Storm Water'.
if ($feature.typeField == 'Storm Water')
{
return `${$feature.typeField} ${$feature.secondField}`
}
else
{
return $feature.typeField
}
Also note: If you have a coded domain, the pseudo code above works exclusively with the raw codes, and not the alias. Below is pseudocode for the alias:
if (DomainName($feature, 'typeField') = 'Storm Water')
{
return `${DomainName($feature, 'typeField')} ${DomainName($feature, 'secondField')}`
}
else
{
return DomainName($feature, 'typeField')
}
As an aside, if you aren't familiar with the backtick notation in Line 3, it's a way of writing your variables directly in-line with your formatting, similar to Python's f-strings. Variables go in curly braces preceded by a dollar sign: ${variablehere}. Anything else is treated as part of the string and is displayed as-is, including line breaks.
If your typeField is "Storm Water" and your secondField is "Foobar" then the result returned by line 3 would be "Storm Water Foobar"