A plumber has issued a stark warning against pouring used coffee grounds down the sink, citing serious plumbing issues that can lead to expensive callouts. Alejandro from EJ Plumbing shared his advice on TikTok after attending multiple callouts linked to coffee-related blockages.
Why Coffee Grounds Are Bad for Pipes
Alejandro explained: "We've been asked if pouring your coffee grains after you're done having your coffee - is it bad for your pipes? Absolutely, it is bad." He added: "You are going to clog all your drains - nothing is going to drain, and you are going to have to get a plumber to come out and snake your pipes and remove all those grains that have been building up inside."
Unlike regular food waste, coffee grounds do not dissolve or break down in water. According to Express Drainage Surveys, which supports Alejandro's guidance, coffee grounds compact and clump together, especially when combined with grease and soap, forming a dense sludge that can block pipes.
The Science Behind the Blockages
Express Drainage Surveys explains: "Coffee grounds have a structure that is oil retentive, granular and fibrous, which means it shares similarities with other common offenders such as rice, pasta, eggshells and cooking oils." The oil residue from coffee can stick inside pipes, and when grounds bind to fats, they create an almost immovable layer that slows water flow and encourages bacterial growth. This process is a key contributor to fatbergs, which have been a notable issue in UK sewers, particularly in London.
Alternative Uses for Coffee Grounds
Instead of pouring them down the sink, spent coffee grounds can be repurposed as garden fertiliser. Former royal gardener Jack Stooks outlined in his own TikTok clip: "Coffee grounds can be used in the garden as a fertiliser. Like most fertilisers, it consists of the elements NPK: nitrogen, phosphorus and potassium." He noted that it is perfect for distributing across borders to encourage large, robust flowers.
Jack also highlighted that coffee grounds attract worms, which improve soil aeration. In bulk, coffee grounds can serve as "thick mulch to place over the soil and around plants," helping to "suppress weeds, lock in moisture and act as a physical barrier to the wind and sun."
Expert Consensus
Both Alejandro and Jack's advice aligns with broader guidance from drainage specialists. Pouring coffee grounds down the sink is a common mistake that can lead to costly plumbing repairs, while using them in the garden offers an eco-friendly alternative that benefits plant growth.
