I tried searching for a old thread on this but I couldn’t find anything relevant.
We live in a new house with a modern septic system and leech field, and my wife feels it’s okay to dump the coffee grounds from our drip coffee maker down the kitchen sink. I’m concerned about it clogging up the pipes eventually, and also what the acidic grounds might do to the septic system. As a result I always dump them in the garbage and just rinse the gold basket out in the sink.
So is it okay to dump coffee grounds down the sink or should they always go in the garbage? Or does it really matter?
Generally speaking, if you have a septic system, then throwing anything down the drain that you don’t have to is strongly discouraged. You can use a garbage disposal, but use it sparingly.
This aside, coffee grounds, en masse, have a pretty good reputation for clogging drains. So I’d either throw out the grounds or put them in the garden where they can be useful.
with a septic system you shouldn’t put anything down the sink drains but water, flush nothing but human waste and minimal toilet paper. household chemicals can also have detrimental effects on your septic, use types that are less harmful and in low amounts.
go to your state department of natural resources and to your university extension and get what information they can provide on septic system care and composting.
if you get a fact sheet or booklet then it isn’t your opinion but information you’ve learned that could save you many thousands of dollars due to septic system failure.
Good idea. Here’s one from the EPA [PDF!]. See Waste Disposal on page 8. Although, it advises not flushing coffee grounds down the toilet, it does explain that all wastewater from the house goes through the septic system, so you could logically conclude coffee grounds down the sink drain have the same impact on the septic system as it does going through a different portal.
on a septic system, nothing other than water down the drain.
on a city sewer, with a garbage disposal, the minimum amount of foodstuffs down the sink, and especially NO - pasta, coffee grounds, rice, vegetable peelings, or meat. The majority of clogs that plumbers have to clean up are from people that think a garbage disposal allows them to put any type of garbage down the sink.
in a septic system the bacteria only works on human waste. vegetable matter sits there and clogs your outflow filter if you have one or gets into your drain field.
with city sewers you need a long strong flow of water to wash it through all your plumbing out to the large sewer pipe in the street. if it doesn’t get that far it could settle in some low spot in your plumbing maybe causing a plugged drain.
Last summer I helped snake a house’s plumbing. Most of what was screwing up the pipes was coffee grounds, mixed with a little grease.
And that wasn’t even a septic system.
If you have a septic system PLEASE DO NOT put anything down the drain that isn’t pee, poop, or toilet paper. Baby that system.
My apartment building, which is well-and-septic, once had a tenant who’s toddler went through a “flush things down the toilet stage”. It was… a very bad time.
Um… you do know that no matter how well you treat your septic system the tank will need periodic cleaning, yes? The less stuff you put down the drain the less often that will be needed. Put lots of non-bodily waste down the drain and you may be shelling out $500 a year just to get the tank cleaned. Put nothing down but bodily waste and greywater and maybe you can go three years (or longer if you have a large enough system).
Also, if you screw up your septic tank or the drainfield that comes out of it you might contaminate your groundwater. Which means your well water. The water you drink and cook with and wash with.
Ask your wife if putting the coffee grounds down the sink instead of the trash can is really worth all that.
Also - if you do have a well get the water tested regularly. Just in case.
Think I’ll need a cite for that. Vegetable matter decomposes pretty well even in the refrigerator or the compost pile – is it the inside of a septic tank particularly anaerobic?
For the record, I have a 1500 gallon septic tank, a garbage disposal, and one occupant (the tank is sized on the optimistic premise that I have 4 bedrooms in the house). I just pumped it after 6 years and there was only six inches of sludge in the tank. (Cost, btw, was about $250.00). So some small amount of excess material can apparently be sent down the drain as long as you don’t make a habit of it and have a well-designed septic system. But something like coffee grounds would be a pretty much daily occurrence and pretty high volume.
Well, of course, a large system sized for a garbage disposal and more people than actually living in the house will be able to go longer between pumpings… but your point about frequency is a good one.
The more solids you put down the drain and into the septic tank, the more you reduce its capacity and the sooner you need to pump it. No solids degrade totally, and some degrade less than and slower than others. I’d say it isn’t smart to put coffee grounds down the drain when you have easy alternatives, like using the household garbage.
People into gardening love coffee grounds for their gardens. Many will go to coffee shops to collect their coffee grounds. Starbucks has (or at least had) a program to encourage this. Something to consider instead of throwing them in the garbage.
garbage disposals produce fine vegetable matter, this can be suspended in the tank (neither sinks or floats) which doesn’t get caught by the baffles in a two chamber tank and then can clog your outlet filter if you have one or plug your drain field.
If you do not have a septic system, coffee grounds are perfect for putting down your sink with running hot water. They scour your drain and pipes and degrease them. If you have a disposer, turn it on and the water also BEFORE putting the grounds down the drain. I was a service plumber for years, and coffee grounds were NEVER found in a drain I repaired, unless they were behind something else that caused the clog. They are acidic and mildly abrasive, perfect for drain cleaning.
However, they should never be put into a septic system, because they will destroy anaerobic bacteria that are needed in that system.