I've seen several great help answers on this topic. But I have a new question. My hot water pressure dropped down to 20 percent. I assumed from these other posts that it was crud blocking the line, and back pressure would blow it out. My kitchen faucets is new American Standard only 18 months old, works great. My hot water heater is only 4 yrs old; the water is draining clear, no crud.
Please look at this photo. I'm in a 1960 house with old galvanized pipes; lots of crud. I cleaned out the aerator. My repair guy agreed the line at the kitchen faucet was likely clogged up with debris. So he removed the hot water handle section on the pipe under the sink - and removed this *brass stem piece and rubber washer*. He said the rubber washer had become "folded over" into the pipe, and caused the partial obstruction. I said that makes no sense, since the washer would have to be installed improperly in the first place; how can such a hard rubber washer “fold over”? He said that water pressure somehow folded the washer. So I asked if he would "back pressure" the pipes anyway - just to make certain any "crud" would not re-lodge into the faucet lines. He said that's not required, and may create lots of new problems. The hot water pressure is restored. Is there such a thing as a rubber washer folding all by itself - and causing this partial block? Thanks for your inputs here!! -doc

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