Water supply mystery

Did a warranty inspection on Friday morning on a typical home for the area. Nothing huge found and homeowner was pretty knowledgeable and followed me for the whole inspection. Nice guy, no problem with him following.

Friday around 5 I got a call from him with a strange question. “Did you do anything that would have caused the water to be off at one of the master vanities and in the kitchen?” Of course my answer was no, which is what he thought since he had been with me the whole time. They had gone out after my inspection and when they returned, those two fixtures had no water - hot or cold.

They have had some problems with the water heater and circ pump, so they are sensitive to them being defective - but that would not explain problems with the cold lines. I racked my brain for possible reasons that this could have happened. Not reasons that would be my fault - that is not the issue - but just answers. The house has PEX plumbing, but it is installed in series - no manifold - because they optioned for a circulation pump on the tank. Nothing unusual was found on the plumbing, with the exception of finding one improperly secured PEX line in the attic.

After brainstorming on the phone for a bit I told him he needed to call the plumber and to call me back to let me know what they find. The plumber came out and could not figure it out. Left them for the weekend saying that they would find the plumbing schematic and send out someone more senior on Monday.

Was curious is anyone had any ideas what could have happened. Couple more facts or opinions. I think it is likely that the two fixtures not working are the last ones on the line. They could also be first, but it makes more sense to me that they would be last. The homeowners said they had never run the master tub/jacuzzi. I do not know if that means it has never been filled. There was a small amount of some residue on the tub when I filled it to run the jacuzzi. I thought it was just cleaning or bath product residue.

I know this is a stupid response but any one check the screens .

Not stupid. It occurred to me, but then I thought, completely stop the water supply to two different faucets? Seems unlikely. I would hope the plumber tried that, but who knows.

I had it once , only but it did happen. LOL no one thought of it.
I use the KISS method

Update.

Just got off the phone with the client. Wanted to double check that someone had checked the screens. Nice call Wayne.

Plumber was back out already and this time did check them. They were severely clogged with a blueish residue. The client describe it to me as looking like powdered Tide or Comet. They also had the city water company out. They checked the water and said it was still safe. The prevailing theory of the plumber and water district is that the water heater is bad. The plumber is checking some stuff and will be back.

The water in this area is pretty full of crap and minerals. I have never noticed it being blue before. I do not see how the water heater would have filled with residue with a recirc pump operating constantly. I would expect that to limit mineral and sediment buildup. Besides the unit is only one year old. What would be blue in a water heater tank? The blue part makes me wonder about something related to the PEX. But I have never heard of anything related to that kind of problem with PEX.

I also still wonder how the running of all the fixtures for the inspection precipitated the clogging of those faucets. This house has been lived in for a year and all the fixtures have been used to some extent. I did get clarification on the jacuzzi use. They have used the faucet but had never used the Jacuzzi or completely filled the tub.

So the clogged screens answers the original mystery, but produces another. Any thoughts?