Are these all one plumbing problem or many?
January 16, 2024 4:05 PM   Subscribe

Hello, I have a 100+ year old rowhouse in Washington, DC. Over the last few weeks, I've noticed several new plumbing issues. Are these related? What should i ask the plumber when i call?

#1: Water at various faucets will occasionally "pulse". Rather than the usual stream of water, I'll get a very rapid pulsing stream. This happens in the shower upstairs, the bathroom sinks upstairs and downstairs, and the kitchen. I can't figure out any pattern. It will just go away in a matter of 30 seconds or so. The water continues at decent pressure, there's just a very rapid pulsing (like a shower massage setting). I was still able to shower successfully. It seems to be cold water, not hot water.

#2 Both toilets recently were clogged and required plunging. This usually happens only once or twice a year, but this was on the same day. While plunging, i realized that my 20 year old plunger had dried out and cracked, so it was much harder to use. I subsequently replaced it. Did using the failing plunger cause damage somehow?

#3 Basement toilet has low water levels in the bowl, but not in the tank. No obvious leaks anywhere. Not running.

#4 About two months ago I replaced both fill valves (Toto toilets, used Korky replacements). I'm not handy, but have done this in the past, so I was confident that i did it correctly. Both valves make identical pulsing noises that come and go intermittently, and water seems to enter the tank while the noise is happening. The flappers seem fine, and no water seems to enter the bowl. I haven't been able to ascertain if they make the noise simultaneously.

So I assume the pulsing of the fill valves and the pulsing of the cold water are related. But which is the cause and which is the symptom? Does this sound like a series of issues or a single cause? FWIW: this predates the recent cold snap in the mid-Atlantic. Water bill has not increased, so I don't think there's a leak. The basement toilet was snaked about 6 months ago when there were burbling sounds down there, which have not returned.
posted by jindc to Home & Garden (10 answers total)
 
Odd question by was there a reason for toilet valve replacement in both at same time? Wondered if you replaced because of slow/sluggish filling which would maybe suggest some kind of larger water pressure issue.
posted by countrymod at 5:08 PM on January 16, 2024


Best answer: 1. If this just started happening recently, you may have a water hammer arrestor that has stopped working. Sometime this can be fixed by shutting off the water and draining water out of the system.

2. Using the plunger could have caused damage if part of it cracked off and clogged the drain. This is not related the first issue.

3. I don't know anything about pluming for basements, other than that there are usually different provisions for basement drains.

4. The pulsing of the fill valves is related to the pulsing of the cold water because the fill valves are attached to the cold water system. If your cold water from other valves started pulsing immediately after you replaced these valves, yes, something could have happened during the replacement which would have caused this. Did you turn off the water at each toilet for the fill valve replacement, or turn off the water to the entire house?
posted by yohko at 5:14 PM on January 16, 2024 [1 favorite]


1) Multiple possible causes for this one. Does your house have a water pressure regulator at or near the the water service entrance to the house? If so, look to it as the cause. They are usually serviceable.

Does your house have a check valve, to prevent backflow into the supply? This is less likely, but if you house has one of these, check it as well: there are regimes of water supply restriction above the check valve that can cause the this pressure pulsing as well.

2) Different problem than #1, perhaps a partial blockage in the drain below both toilets, reducing the scouring and velocity through the toilet trap needed to keep it clear, encouraging blockage. Your failing plunger did not do any damage.

3) Different problem than #1 or #2. Basement toilet has a partial clog high in the trap. This allows the water to siphon out after a flush, resulting in a low bowl level. It is likely that this toilet also does not flush freely, backing up into the bowl further than usual because of the restriction in the trap.

4) A consequence of #1, and not likely a problem you have to fix. The fluctuating pressure in your water system is interacting with your float valves. When the float valve has filled the tank and shut off the supply, it will re-open and admit water to the tank again if you increase the supply pressure until more force is applied to the valve seat by deeper submergence of the float. This is normal.
posted by the Real Dan at 8:00 PM on January 16, 2024 [1 favorite]


If the pulsing started at one particular outlet and has since spread to others, the cause is more likely to be worn and/or loose valve washers in those specific outlets than something more centralized like a failing water hammer arrestor or inlet pressure regulator.

On the other hand, if they all started pulsing at the same time then it's probably a whole-house pressure regulator's control element doing its impersonation of a saxophone reed. Water is much denser than air and your house's pipework much bigger than a saxophone, and together those factors make the "note" being "played" low enough to be perceived as rhythmic rather than tonal.

Failing hammer arrestors will more often cause bangs and thumps when valves get turned off than when opened, and the faster the valve closes the more jarring and possibly damaging those bangs will be. So if there's a failing water hammer arrestor you're more likely to notice it as your washing machine or dishwasher shuts off an incoming burst of water than when you turn your taps on. Float-controlled toilet cistern fill valves usually shut off much more gradually than washing machine solenoids do, so water hammer from those is pretty rare.
posted by flabdablet at 8:30 PM on January 16, 2024


A failing plunger won't damage anything, by the way; it will simply not slosh the contents of your drains about as enthusiastically as a new plunger would, and be less effective at transmitting the force of your elbow to whatever is clogging the drain.
posted by flabdablet at 8:33 PM on January 16, 2024


Low water levels in a toilet bowl can be indicative of a blocked drain vent downstream from that bowl.

Normally, with a properly ventilated drain, the water that sits in a toilet pan before it's flushed will see equal atmospheric pressures on both the upstream surface that you can see and the downstream surface hidden inside the siphon.

If the drain vent is blocked, then as a bolus of flushed water continues to drain away after the water seal is re-established at the end of a flush, there's no source of outside air to replace it, so the air pressure inside the drain ends up below atmospheric.

In effect, the toilet pan operates as a manometer measuring the air pressure inside the drain.

In a related effect, if the wind blows just right so as to turn an entire ventilated drain system into a very low pitched flute, you'll sometimes see the level in your toilet bowls pulsing. If that happens repeatedly it can suck and splash a fair bit of the standing water from the toilet pan down into the drain. So if you live somewhere windy, a toilet pan that you don't use very often might end up with less water in it than normal.

In theory, a gust of wind that hits a vent just right could even trigger a US-style syphonic toilet pan to start a flush on its own and end up mostly empty.

None of the above has anything to do with faults in the toilet cistern or the fresh water pipes that feed it; your mysterious pulsing won't be contributing in any way to your shallow basement toilet.
posted by flabdablet at 8:56 PM on January 16, 2024


Response by poster: Thanks to everyone for their thoughts and suggestions. A couple of answers:

Toilets were installed new 10 years ago, so i think the float valves died at the same time purely through age and use. They were both leaking and the toilets were running. I did replace the float valves with fill valves, so slightly different technology.

I don't have any sort of water pressure regulator that i'm aware of. I believe there are backflow preventers on the hot water heater and the boiler, but i don't think there's one on the main water service line.

I turned off the water service at each toilet when replacing the fill valves, but did not turn off the main water service line.

The basement toilet drain vent is in the wall, and does not go up to the attic and the roof (this was installed as part of a full basement remodel 10 years ago. There was not a bathroom down there originally). So I don't think windy conditions outside should be involved. There's no pulsing or splashing in the bowl.
posted by jindc at 6:09 AM on January 17, 2024


Best answer: Water hammer arresters are basically air voids connected to your plumbing. Air is very compressible (whereas water and pipes/plumbing fixtures are not) so when a sharp shock comes along your pipes, the air can absorb it, stopping the hammering. The hammering typically manifests are a rapidly pulsing stream - often accompanied by loud knocking sounds (thus the name "water hammer) - of the type you describe.

If the air chamber becomes completely filled with water, which can happen over time, then the shock absorption capability of the air chamber is lost. Thus the suggestions upthread to turn water off at the main & drain the entire system as best you can. Often that will drain the chamber of the water hammer arrester and all is well again.

The arrester is usually a vertically oriented tube or chamber - sometimes just a regular water pipe - connected to the plumbing only at the bottom. The upper part contains the air.

In one house we had had a fancier version of this - a large bulbous chamber like this that has a rubber membrane inside. You're supposed to keep it inflated with air, using something like a bicycle pump, to some certain PSI.

This worked great until #1. I forgot to keep it pumped up at all and #2. The rubber membrane developed a leak, allowing the entire chamber to fill with water.

At that point it was just a large, very heavy, globe of water that had no water hammer or excess pressure absorption capabilities at all.

Points being:

- You can look around & see if you have any of the smaller vertical hammer arresters installed. If so they might benefit from draining the water to ensure their chamber is filled with air, not water.

- If you have one of the large tank installations (which does absorb expansion from, say, a water heater - usually that's what they're sold for more so than watter hammer arresting, though they will do both) those are likely to fail and need replacement and/or at least service after 10-20-30 years.

- If you don't have either of the above you might need a water hammer arrester installed.

- If you have a lot of water hammer it is often (or sometimes) because the pressure into your house is very high - thus the mention above of pressure restrictor valves. We live a couple of blocks from our city water tower, the pressure into our house is REALLY high, and installing a pressure check valve and adjusting it to the right pressure made a big difference in resolving these issues.

These are all things a plumber will know all about, they should bring them up with you if there are issues with them, but they might not. So they're worth keeping in mind and asking the plumber about them, depending on how the plumbing visit goes.

FWIW very high water pressure can lead to hammering and also premature failure of things like toilet fill valves. Those things are pretty lightweight and subjected to tremendous, continuous pressure if your household water pressure is too high. So definitely worth investigating.
posted by flug at 6:27 PM on January 17, 2024 [1 favorite]


Response by poster: Diagnosis: water hammer. It doesn't appear that I have a water hammer arrester, so that will be added soon.
posted by jindc at 7:09 AM on January 23, 2024 [1 favorite]


Until that happens, you can reduce hammer by hand just by turning your faucets on and off very slowly, giving the water contained inside the pipes more time to accelerate and decelerate. It's worth doing, because hammer can crack pipes and cause expensive-to-remediate leaks inside your walls.
posted by flabdablet at 10:53 AM on January 23, 2024


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