If you drink a lot of fresh coffee, then you'll have to dispose of regular supplies of used grounds. You may have heard that the best way to get rid of old grounds is to put them down the sink. Some people say that this is good for your pipes, but others say it isn't because it causes drain blockages. Who is right?

Do Coffee Grounds Clean Sinks?

Some coffee drinkers put grounds down their sinks because they believe that the grounds' abrasiveness cleans their waste pipes. The principle here is that the rough grounds rub against the inside of pipes as the grounds travel through to the drain. This rubbing dislodges scum and grease that builds up in the pipes and makes them cleaner. As well as a spring clean, the coffee grounds are supposed to make sinks smell fresher by cleaning away scum that might otherwise start to smell if it is left in place.

While this may be a sound theory, it doesn't always work. You need to get some pressure going when you rinse grounds down a sink to make them hit the sides of pipes. Also, they may not clean all areas. Even if this solves a scum problem, your coffee grounds are also likely to create a more serious plumbing headache.

Do Coffee Grounds Block Drains?

Regularly washing old coffee grounds down sinks can cause problems. You need a lot of water to get just a few grounds down your sink and through its pipes. If they don't all flush away, some will sit in your sink trap or bend. If you carry on putting grounds down the sink, more collect in these areas. Eventually, you have a large clump of wet coffee grounds that start to block your drain. These grounds won't wash away easily, if at all, and they don't dissolve in hot water. They are also hard to shift even if you use a plumber's tool that slots down drains to clear blockages. Coffee ground lumps may be solid enough to stop water draining correctly, but they are still soft. Plumber's tools push through them rather than pushing them out through the pipes

If you've been sticking your used grounds down your sink and you've noticed that it isn't draining like it used to, then you're probably building a coffee grounds blockage. Before things get worse, call your plumber and ask them to clear your blocked drain.