From time to time my kitchen sink needs to be unplugged, and each time I invariably find accumulations of a crusty, crumbly white material in the pipes. It looks a lot like old cheese, has no particular odor of note, is often in ring shapes (so I assume it is accumulating against the pipe walls), and can be quite hard at times requiring a fair bit of manual force to snap out of place.

These accumulations don't occur at our bathroom sink and bathtub drain, both of which have corrugated plastic hosing, so I suspect it is biological (feeding off sink detritus) rather than mineralogical?

Just curious!


It sounds like calcium build up to me, are you sure it's not mineral? Is your water hard? When I have replaced the PVC pipes in my sink, I occasionally see exactly what you describe, but in my case it is because of our hard water.

  • +1 sounds like to me. A little CLR will clean it right off if that's the case. – BMitch May 20 '11 at 16:28
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    The OP said not in other pipes so accepting this answer is bizzare. – Ed Beal Nov 4 '17 at 1:33

It is a build up from residual grease from the kitchen, apparently some of the grease from plates left overs, pots and pans are not completely emulsified (diluted in soap) when doing dishes and over time they create that build up.


I just recovered two big (6") chunks of a bouyant, white chalky pipe-blockage from my tank. No, it is not slippery. It feels like one might expect wet chalk to feel, or joint compound that has about 90% of the stickiness removed. There is a bit of black nastiness on the outside, but the inside is surprisingly white for something from a sewer pipe. Right now I have samples soaking in bleach and vinegar.

In general terms, there are only three things you could pour down the drain besides water to fix problems: A base (high pH), an acid (low pH), or an organic solvent.

One would be silly to pour an organic solvent (i.e. gasoline, paint thinner, acetone, or dry cleaning fluid). If you didn't dissolve plastic pipe, set the house ablaze, or seriously pollute the environment, you still probably wouldn't dissolve enough to make a difference.

A base is great stuff. It turns grease into soap. It denatures protein (including hair). You probably have baking soda (weak) or bleach (not quite as weak) in the house. If you need more, buy lye or drain cleaner (lye in a fancy bottle).

Acid will dissolve calcium deposits. I have calcium deposits in my shower nozzles and in my toilets, but I'm not convinced it filled my sewer line. Here is one bit of chemistry you should know, though: calcium salts are less soluble in hot water, so dumping hot vinegar in your drains is counterproductive.

In the acid lineup, 5% vinegar is the starter. Citric acid is good for freshening your dishwasher, oxalic acid takes cat-pee stains out of a wood floor, and manly men use muriatic (hydrochloric) acid to clean up bad tiling jobs. They also use gloves and glasses and ventilation.

Too much of either acid or base will kill every microbe in your septic system or sewer. When the microbes wake up from the dead, it may smell bad. Use of chemicals may cause junk to flow out into your drain field. Any one of these events can be smelly or expensive.

When you read helpful hints on the internet, any solution that tells you to mix baking soda and vinegar is wasting your time. It bubbles -- remember the volcano you made in fifth grade? After the two mix and make CO2, you have no more acid or base. You might as well use plain water.

My sample soaking in bleach has lost some integrity. No ferocious reaction or bubbles, but the sample is breaking up. The sample soaking in vinegar shows no change. It may be dissolving, but it's not visible. My lab is just two Pyrex dishes on the counter. Your mileage may vary.

A little more chemistry before I finish this rant: soaps aren't what they used to be. When your grandmother loaded her washer and dishwasher in the 60's, she had the best chemistry industry could provide: tri-sodium phosphate, a really great surfactant (detergent). It was removed from clothes washing detergent twenty years ago and from dishwashing detergent ten years ago. You thought your dishwasher wasn't working well anymore? Nope. The new soap is no good. It has some cool enzymes to breach down food protein, but wimpy detergent to take care of grease. It isn't as good a fertilizer, either, so it doesn't cause blooms in river and lakes.

If you don't feel comfortable with the concepts here, swallow hard and call a professional. You may not like the answer, but at least it's not one made up be someone on the internet. ;^)


We found the same thing stopping up our sink pipes all the way to the septic. It was so prolific we had to replace all two inch pipe from the sink to the final drain. We believe it is some grease, some residue from a hardly used disposal unit, hard water, and a build up of dishwasher undissolved detergents. If you could run a light acid solution through the pipes such as vinegar once monthly this might not happen. Use of other harsh cleaners is not recommended due to early damage to any metal piping. If you have all plastic pipes and no septic, you might use other biodegradable cleaners which contain some chemical which will dissolve calcium deposits.

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