So apparently, the 3.5
City of Splendors: Waterdeep book had a web enhancement, one titled, wait for it...
Noble Houses of Waterdeep. It lists every noble family in the city, along with a decent amount of salient information, including the predominant alignments.
Now, that's a little awkward, because in many cases this notes quite a few different alignments, many of them quite disparate. Still, if we look at which ones are listed the most (along the good/evil axis), we can get a sense of their overall general disposition (if there's an even split between neutrality and a single other alignment, I've presumed they'll lean at least somewhat toward the latter). The list is as follows:
- Adarbrent (LG, NG, CG) - Good
- Agundar (CN) - Neutral
- Amcathra (LG, NG, CG) - Good
- Ammakyl (NG) - Good
- Anteos (LN, LE) - Evil
- Artemel (CN, N, NE, CE) - Evil
- Assumbar (LG, LN) - Good
- Belabranta (NG, N) - Good
- Bladesemmer (CG, NG, CN) - Good
- Brokengulf (CN, N, LN, LG, NE) - Neutral
- Brossfeather (N, NG) - Good
- Cassalanter (CG, NG, CN, N) - Good
- Cragsmere (CG, CN) - Good
- Crommor (CG, NG) - Good
- Dezlentyr (LN, CG) - Good
- Durinbold (CN, N) - Neutral
- Eagleshield (CN, CG) - Good
- Eirontalar (CG, NG, CN, NE) - Good
- Eltorchul (LN, CG, LG, NG, CE) - Good
- Emveolstone (LN, N) - Neutral
- Estelmer (NG, N) - Good
- Gauntyl (LN, LE) - Evil
- Gost (NG, CG) - Good
- Gralhund (LN, LE) - Evil
- Gundwynd (LG) - Good
- Hawkwinter (NG, CG, LG) - Good
- Helmfast (CG, NG, CN) - Good
- Hiilgauntlet (N, CN) - Neutral
- Hothemer (CG, CN) - Good
- Hunabar (LG, N, CE) - Neutral
- Husteem (LN, LE, N, NE) - Evil
- Ilitul (N, LN) - Neutral
- Ilvastarr (N, CN) - Neutral
- Ilzimmer (CE, NE, N, CE, CN) - Evil
- Irlingstar (CG, CN, CE) - Neutral
- Jardeth (LN) - Neutral
- Jhansczil (LN, N CN) - Neutral
- Kormallis (LN, LG) - Good
- Kothont (LN, LE) - Evil
- Lanngolyn (N, CN) - Neutral
- Lathkule (N) - Neutral
- Maerklos (LG, LN, LE) - Neutral
- Majarra (NG, CG, LN) - Good
- Manthar (LN, N) - Neutral
- Margaster (CN, CG) - Good
- Massalan (NE, N) - Evil
- Melshimber (NE, LE, N, LN, LG) - Evil
- Moonstar (CG) - Good (it notes that the Vanrak lineage specifically is CE, but according to what's in the full book, that lineage is largely out of power now)
- Nandar (CN, CE) - Evil
- Nesher (CG, CN, CE) - Neutral
- Phull (CG, CN) - Good
- Phylund (LN, NG, NE) - Neutral
- Piiradost (LN, N, CN) - Neutral
- Raventree (NG, N, CG) - Good
- Roaringhorn (NG, CG, N, CN) - Good
- Rosznar (CE, CN, NE, LE) - Evil
- Ruldegost (LN, N) - Neutral
- Silmerhelve (LN, LG) - Good
- Snome (LG, NG, LN) - Good
- Stormweather (CN, N, CE) - Neutral
- Sultlue (CE, NE, CN) - Evil
- Talmost (LN, N, NE) - Neutral
- Tarm (NG, CG, CN) - Good
- Tchazzam (NG, CG) - Good
- Tesper (LG, NG, CG) - Good
- Thann (NG, LN, LG, CG) - Good
- Thongolir (NG) - Good
- Thorp (LN, N) - Neutral
- Thunderstaff (LG, NG, N) - Good
- Ulbrinter (N) - Neutral
- Urmbrusk (LN, N, LE) - Neutral
- Wands (NG, LG, CG, LN, N, CN) - Good
- Wavesilver (CG, NG, CN) - Good
- Zulpair (CN, CE) - Evil
- Zun (CN, N, CE, NE) - Evil
So breaking that down, we have the following distribution:
Good: 37 houses.
Neutral: 24 houses.
Evil: 14 houses.
In other words, nobles houses with a predominantly good alignment make up almost half of Waterdeep's nobility, those which are neutral are just shy of one-third, and those of a decidedly evil bent are a tad bit over one-sixth.