Cleanng a brush used for water-based paint, with soap or not?

Question

After painting with water-based paint I usually clean my brushes (or rollers) by simply rinsing them under running hot water (as hot as my hands can take) straight from the faucet.
After thorough rinsing I shake of the water as much as possible and hang them somewhere, with the hairs down, to further leak out and dry. This has served me well for years.

Now a friend of mine is telling me I should rinse the brushes with soap and warm (but not HOT) water.

After some Googling around I find that both variants seem about equally popular.
The pros and cons given for either method range from "sounds sensible" (soap may leave a residue in the brush affecting the next paint-job) to rather bizarre (hot water dissolves the hairs of the brush).

So I like to hear your opinions. Preferably with arguments for one method or the other.

Answer 1

I get observably better result with dish detergent - less partially dried paint bits left stuck in the brush.

Detriment, if any, of very hot water might depend on brush construction. I doubt it would "dissolve the hairs" but it might damage some of the plastic bristles typically used for latex paint brushes. I prefer lots of water to particularly hot. I start rinsing cold (usually at the outside tap) and move to warm water and soap inside after getting the bulk off outside.

Extremely thorough rinsing is required whether or not you use soap. I normally do a crude rinse, work some soap into the bristles (with dilute paint still in the brush), and then proceed to the serious rinsing. If any color comes out of the brush, it needs more rinsing. If your rinse procedure is thorough enough to get all the paint out, it will get all the soap out. If it's not, you might as well use disposable brushes and not bother washing them at all.

Answer 2

I'll use a bit of dish detergent if I think it will help. Rinse thoroughly to remove any residue.