Fickle faucet flows at a trickle

Q: Here’s a poser for you. It is neither a problem nor an inconvenience – just a puzzlement!
Why does the water pressure in my bathroom sink’s Delta faucet vary so much? Sometimes it is just a trickle, other times it’s a good normal flow, and sometimes it’s in between. The kitchen sink, bathtub and washing machine operate normally. It is not the screw-on filter, as a plumber suggested, because I keep that clean. I moved into this house in 1982 and the single lever (ball handle) was here at that time. The water pressure began to change about a year ago.
At first I thought it was caused by the sprinkler system, the washing machine, or toilet flushes. Not so. If it’s somehow connected to the main water system coming into the house, why isn’t everything affected? Thus, a puzzlement.
It is an old house. Built in 1907 — but solid. Lots of charm. – Gaylord T., Spokane
A: You must be a patient individual to live a year with a faucet not working to its full potential. Let’s see what can be done to rectify the problem.
Since your home was built in 1907, you probably still have galvanized pipes, unless someone changed out the galvanized pipes to copper. All galvanized pipes eventually rust on the inside, and anytime the main water is turned off, drained and turned back on, the force of the water carries rust particles and flakes to all outlets. That’s why it’s a good idea to turn off the faucet and check the aerator (the screw-on filter at the end of the spout) for any foreign material at each sink in your home. With the aerator removed, flush the lines by turning on each faucet for at least a minute or two.
In your case, it sounds like a flow issue, possibly a very small pebble or rust flake inside the faucet is moving around and restricting water flow. It’s also possible that the brass rotating ball assembly, which has a slot on the right side that fits over a pin (also found on the right side) down in the faucet ball’s seat, is worn out. This worn slot could allow the ball to shift just enough to restrict water flow. The rotating ball controls the temperature and flow of water into the faucet.
It’s also possible, but unlikely, that there is something in the spout tube, or there could be mineral deposits around the ball assembly. Clean off the deposits by soaking the ball assembly in warm full-strength white vinegar if you decide to use the existing part instead of purchasing a new one.
With a faucet this old, I would recommend a tune-up. Purchase a faucet repair kit and other parts relating to your faucet at a local home center. Hopefully, you have shut-off valves conveniently located under the sink to shut off the water to the faucet. Then remove the aerator, finished handle button, handle screw, handle, adjusting ring and cap, cam with packing, ball assembly, and seats and springs.
Run a wire up the spout to make sure that there’s no foreign material in the spout tube. I would also flush the faucet for any foreign material, which will require a helper, towel and a bucket. First wrap the towel around the faucet and make sure the towel fills in the area between the faucet and the backsplash. Next place the bucket upside down over the faucet. While you hold the bucket with both hands, have your helper turn on the hot water for about 5 seconds. Do the same for the cold water side. Five seconds should be enough time to flush both supply lines and faucet — any longer and you’ll flood the bathroom. This should take care of any foreign material inside the faucet.
Now reassemble the faucet with (hopefully) new parts, but run the faucet for a few minutes before you reinstall the aerator.
To check out the internal parts of your faucet before you disassemble it, go to www.deltafaucet.com and click on “Customer Support.” On the right-hand side under “Technical Documents,” use the search engine by clicking “Lavatory” under “Bath” in the first box labeled “Room/Function.” Under the third box labeled “Holes,” click on “2-Hole” and then click on the search button directly under it. When you reach the results page, click on the “Classic” image that resembles your handle. On the next page that comes up, click on “Parts & Accessories Diagram.” This link will direct you to a .pdf file with informational diagrams about your faucet.
Gaylord, I’m curious about what you’ll find when you take apart the faucet, so please let me know the outcome. Good luck.