I just replaced the pressure balancing valve and valve mixer cap in a shower that had lost its hot water. Replacing the parts fixed the problem, but when I pulled the old valve out, it was covered with a chunky white "crud" (see attached pictures of the valve and the inside of the valve body). I'm concerned that this crud will build up again and destroy the new parts, and I'll be right back where I started. Does anybody have any idea what it may be?

valve covered with crud inside of valve body full of crud

  • 2
    Water softener or reverse osmosis unit. Those look like mineral crystals. Feb 24, 2015 at 14:57

2 Answers 2


These are just educated guesses since I cannot feel/smell these white deposits:

  1. My best guess is that your dip tube in your water heater disintegrated. This is a very common problem especially if your water heater is 10-25 years old. You simply need to replace dip tube and then go to all valves and faucets and clean them.

  2. Calcium deposits. I doubt this is it because I have seen it so many times that I think would be able to tell. The pieces would look more like rocks. They would have a little bit of greenish white tint. There is no fix for this beyond filtering all incoming water.

  3. Chlorine tablets. Your water source puts chlorine tablets in the water. If you are near the source the tablets may get into your water without fully dissolving. Your issue does not look like this but throwing it out there.

  4. Rubber hoses. Any kind of rubber hose that you have in your plumbing system. Water heater, under sinks, for toilets... These can break down over time and actually the outcome is a lot like yours, except most hoses are usually black.

  • Why initial thoughts were hard water build up or an old dip tube problem. My water heater was replaced in 2007 or so, but the original was from 1994, my suspicion is that my current dip tube is OK but that the remains from the old dip tube may still be in the system, especially as this valve was in an infrequently used guest bathroom.
    – Steve
    Feb 26, 2015 at 18:41
  • You will never find the problem until you find the problem. It could have been from 10 years ago. Until it starts failing who cares?
    – DMoore
    Feb 26, 2015 at 18:43
  • A broken or disintegrating dip tube would cause issues with hot water delivery. Usual complaint would be hot water for short period followed by luke-warm water (the dip-tube directs incoming cold water to the bottom of the heater, away from the hot water outlet. When broken, incoming cold water mixes with the heated water near the outlet). Feb 27, 2015 at 17:21
  • While this isn't so much a single answer as it is a multiple choice answer, I think this is as close as I'm going to get, since as @DMoore noted, I won't ever really know.
    – Steve
    Mar 2, 2015 at 20:18

Those are hard water deposits (lime, scale, minerals). The only way to prevent is to install a water softener... or move to a different part of the country or world. CLR does a good job removing that stuff.

  • I thought that but it looks a bit yellow and spongy. Maybe we need more clarification.
    – DMoore
    Feb 25, 2015 at 7:16
  • What other clarification would help? It's definitely chunkier than hard water build up I've seen elsewhere.
    – Steve
    Feb 26, 2015 at 17:06

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