About those coffee grounds going down the sink drain...

Want to talk espresso but not sure which forum? If so, this is the right one.

#1: Post by ZebcoKid »

Hello All,

So I'm deep into espresso making. Although I use a knock box to capture most of the grounds, theres a decent amount that make their way down the drain in the kitchen sink (rinsing the portafilter). Is this something that will haunt me later...or not something to worry about?

Thank you.


#2: Post by Mashie »

I don't have a knock box and have been dumping my grounds down the sink for years without any problems.

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#3: Post by slybarman »

I can't see espresso grind getting caught in the trap. Too light/fine.

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#4: Post by civ »

Mashie wrote: ... don't have a knock box ...
I have a knock box made from the female end of a 5" thick PVC drain tube but eventually it has to be emptied.
Once a week or so, I mash up the spent pucks and flush it all down the toilet.
I expect that it scrubs the walls of the sewage system as it goes down.

Also, for years now and without any problems.

The grounds do make (not by themselves) excellent material to add to a compost bin.
But I don't have room for one in my balcony.




#5: Post by jpender »

A plumber clearing out a clog downstream of our kitchen sink years ago scoffed when I told him I'd heard that coffee grounds help keep drains clear. He said they were one of the worst offenders for clogging. Did he know what he was talking about? He was a plumber, but that doesn't prove he really knew. I toss the pucks into the compost now but don't get upset that a certain amount of grounds go down the sink.

You know what does clog drains? Hair. Since the start of the pandemic I haven't had my hair cut, first time in my life with long hair. My wife has let her previously short hair grow long too. And I've had to disassemble the pipes below the bathroom sink more than once to clear out incredible wads of stuck hair. I think it isn't coffee drinkers that have to worry about clogged pipes, it's hippies.


#6: Post by chipman »

We were told by our HOA not to put coffee grounds down the sink as they have had previous issues with clogged drains caused by coffee grounds throughout our complex.

I was also told by a plumber that it wasn't wise.

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#7: Post by slybarman »

I would think large coarse drip grinds are a lot more likely to clog than fine espresso grinds. Especially if somebody is dropping the entire contents of their Mr coffee drip machine basket in the sink.

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#8: Post by cazeppa »

We live in a 65 year old house. I've been washing 3 spent pucks down the drain of my kitchen sink for 9 months with absolutely no ill effects. But I'm thinking that, due to the age of our house, the drain lines are a larger diameter than contemporary houses. We do not put any kind of grease down the drain which things like coffee grounds would stick to and build up to a nasty blockage. And I do a lot of dishwashing so there's a lot of warm soapy water flowing through my drain lines, which would flush things like coffee grounds right out to the street.


#9: Post by jpender »

We live in a house that's over 80 years old. The main drain line to the street is a problem that will eventually require that we dig up the driveway and replace it. Every time I run the disposer or wash some grounds down the sink I think about that, about how much it's probably going to cost.

Do finer grounds stick less than coarser grounds? I'm not sure why that would be true. If coffee grounds are a problem for drains it's going to be something that will take time to show up, probably years. And maybe you'll never really know if the coffee contributed to the problem or not.

How do people who say it's a problem know?

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#10: Post by slybarman »

jpender wrote:Do finer grounds stick less than coarser grounds?
I was thinking in terms of size/weight making it more/less likely to settle in the trap versus being carried away, but I'm an not a plumber, so . . .