In early January, I realized I could shut off a couple valves, open the drain valve on the hot water tank and siphon vinegar into the pipes via the bathroom sink faucet.

I let this sit overnight, then ran the water to clear out the vinegar and whatever it had disolved.

I ended up with a lot of gritty black water that smelled like salad dressing, but no improvement in the shower.

So, I decided to follow the grand psychotic tradition of "If it doesn't work, do the same thing again, but harder." I discovered that Lowes sells "Cleaning Grade Vinegar." This is 30% acetic acid, instead of the 5% that we use for salad dressing. This is not so strong that you need gloves to avoid losing a hand if it splatters, but it's well into the "Don't get this in your eyes" range. (I didn't get any in my eyes. )

As before, I closed the main valves, opened the drain valve, and hooked up the old CPAP hose to the acid and turned on the spout.

Acid flowed eagerly into the pipes, and once I'd dumped a gallon into the pipes that feed the sink, and later feed the shower, I ran the shower until I smelled vinegar.

I let this sit overnight.

The next day, I sang the Doobie Brother's hit "old black water, keep on rolling." It was much darker and grittier than the plain old vinegar test.

When this exercise was over, I took a real shower. The shower heads no longer show any mercy.

Taking a shower was was the big excitement this week.