Do the Hogwarts uniforms reflect one's House membership?

Question

I've become so used to the movies that I can't remember (nor find) if there is a passage in the books that explicitly states if the Hogwarts uniforms (that are not as depicted in the movies, I know) reflect one's House membership and, if so, when they start doing so. When bought, the robes must be plain black, of course:

HOGWARTS SCHOOL of WITCHCRAFT and WIZARDRY

UNIFORM

First-year students will require:

1. Three sets of plain work robes (black)

[...]

^{(Harry Potter and the Philosopher's Stone, page 74)}

But what about after one has been sorted? Do they stay black regardless of the House?

I'm not asking about the movies and what kind of magic would be used - as in How do Wizards get their house colours? - but how the uniforms are depicted in the books.

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I've found further details that substantiate the accepted answer:

1. The first time Harry takes the Hogwarts train Percy - Gryffindor in his 5th year - is said to have already changed into his robes and there's no mention of colors or House badges - only his prefect badge (emphasis added):

   “Where’s Percy?” said their mother.

   “He’s coming now.”

   The oldest boy came striding into sight. He had already changed into his billowing black Hogwarts robes, and Harry noticed a shiny red and gold badge on his chest with the letter P on it.

   ^{(Harry Potter and the Philosopher's Stone, pages 106-107)}

2. When searching for the keywords #robe and #badge I found only prefect and Quidditch captain badges (aside from "Harry stinks", Cedric Diggory or Weasley is our king badges) and colored Quidditch robes.

3. Also, when the Gryffindor Quidditch team is training for the first time in CS7, Wood is not able to distinguish Colin Creevey as a Gryffindor student.

4. In CS12, after having drugged Crabbe and Goyle, Harry and Ron steal only the shoes from them, while they use "spare robes" stolen by Hermione "out of the laundry". In both cases, it's because of the size difference, not because of House-identifying colors or symbols.

5. Students occasionally wear scarfs in the colors of their House - mostly during Quidditch matches. This would explain how Harry is sometimes able to tell to which House someone belongs, even without knowing her/him.

Answer 1

I would say the uniforms do not reflect house membership for a handful of reasons.

First, it's very hard to prove a negative. Why would JKR explicitly start talking about a uniform they could wear, but aren't going to be wearing? However, having bought plain black robes as you demonstrate in the question, I would have thought Harry getting his house colours would be something JKR would want to make mention of if it's part of her world. I imagine in-universe it would have a sort of relevance as you take your place in your new house and I rather think that absence of evidence is evidence of absence in this case, because it seems like the sort of thing she would tell us having told us everything else about how Harry became part of Gryffindor and what the common room is like and where the dormitories are. If the uniforms do reflect house membership, I think it would be stated, and if it's stated, the only sensible place would be in chapter 7 (of Philosopher's Stone) The Sorting Hat or chapter 8 The Potions Master and it's relatively easy to verify that it's not. Bit hard to shoe-horn it in elsewhere and you're now overwriting established images in people's minds for no real reason.

In terms of real canon evidence, in The Chamber of Secrets Ron mistakes Penelope Clearwater for a Slytherin when she's in Ravenclaw:

'The Slyterins always come up to breakfast from over there,' said Ron, nodding at the entrance to the dungeons. The words had barely left his mouth when a girl with long curly hair emerged from the entrance.

'Excuse me,' said Ron, hurrying up to her, 'we've forgotten the way to our common room.'

'I beg your pardon?' said the girl stiffly. 'Our common room? I'm a Ravenclaw.'

Harry Potter and the Chamber of Secrets - pp.163-4 - Bloomsbury - Chapter 12, The Polyjuice Potion

Although he could have just not noticed her house colours.

Finally, in JKR's illustrations, we see only plain black robes, for example in the illustration of Snape's potions class shown on Pottermore:

https://www.pottermore.com/writing-by-jk-rowling/potions