From the caption under this photo at <a href="https://en.wikipedia.org/wiki/en:Semantics" class="extiw" title="w:en:Semantics">semantics</a>:  "Color-coding hot- and cold-water faucets is common in many cultures but, as this example shows, the coding may be rendered meaningless because of context. The two faucets were probably sold as a coded set, but the code is unusable (and ignored) as there is a single water supply".
<a href="//commons.wikimedia.org/wiki/User:Vmenkov" title="User:Vmenkov">Vladimir Menkov</a>
CC BY-SA 2.5
<span class="int-own-work" lang="en">Own work</span>