{"id":6376,"date":"2026-10-05T11:01:51","date_gmt":"2026-10-05T09:01:51","guid":{"rendered":"https:\/\/www.limpiezasdomingo.com\/blog\/a-sink-that-keeps-getting-blocked-causes-and-solutions\/"},"modified":"2026-10-05T12:03:16","modified_gmt":"2026-10-05T10:03:16","slug":"a-sink-that-keeps-getting-blocked-causes-and-solutions","status":"publish","type":"post","link":"https:\/\/www.limpiezasdomingo.com\/en\/blog\/a-sink-that-keeps-getting-blocked-causes-and-solutions\/","title":{"rendered":"A sink that keeps getting blocked: causes and solutions"},"content":{"rendered":"\r\n\r\n
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Why does the sink keep getting blocked?<\/h3>\n

A sink that keeps getting blocked almost always has grease stuck inside the pipe.<\/strong> Every time you wash up, that layer traps food scraps and soap; the plunger clears the blockage temporarily, but the grease is still there and the blockage returns within a few weeks.<\/p>\n

It\u2019s a problem specific to the kitchen. The sink ends up with everything that doesn\u2019t go down any other drain in the house: oil, food scraps, coffee grounds and water containing dishwasher detergent. That\u2019s why it gets blocked differently to a washbasin or a shower, and that\u2019s why the solution is different too.<\/p>\n

In this guide, you\u2019ll find out what causes your sink to become blocked repeatedly, how to locate the blockage, what you can do yourself, and when you need to have your pipes pressure-cleaned<\/a> to prevent it from happening again.<\/p>\n<\/div><\/div>\r\n\r\n

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Reasons why a sink keeps getting blocked<\/h3>\n

When a sink blockage keeps recurring, it\u2019s not just a single blockage: something builds up every time you use it. Here are the six most common causes, listed from most to least frequent.<\/p>\n

1. Grease and oil stuck to the pipe<\/h4>\n

It\u2019s the main culprit in any kitchen. The oil flows freely with the hot water, but as it cools it solidifies and sticks to the inside walls of the pipe. Food scraps then get stuck to this layer, and the pipe becomes a little narrower with every wash-up.<\/p>\n

That\u2019s why the suction cup only works for a few days: it creates a hole in the fat, but doesn\u2019t remove it.<\/p>\n

2. Food scraps and coffee grounds<\/h4>\n

Rice, pasta, fruit peel, eggshells and coffee grounds do not dissolve. They settle in the siphon and in the bends of the pipework and, when mixed with grease, form a compact paste. If you\u2019d like to know what other types of waste end up causing blockages, we explain this in the section on materials that commonly cause blockages in pipes.<\/a><\/p>\n

3. Soap and limescale in the trap<\/h4>\n

Soap and detergent residues combine with the limescale in the water to form a build-up in the siphon and the drainpipe. The sink starts to drain more and more slowly, even if you don\u2019t pour food scraps down it. If you live in the Marina Alta, you\u2019ll want to read about how hard water affects your pipes.<\/a><\/p>\n

4. A dirty or incorrectly fitted siphon<\/h4>\n

The trap is the curved or U-shaped section beneath the sink, and this is where most dirt accumulates. If, in addition, it is fitted incorrectly, has an adverse slope or the pipe leading out of it is too narrow, waste will always remain in the same spot. Basic Document HS 5 of the Technical Building Code<\/a> sets out the requirements for diameters, gradients and water seals in drainage systems.<\/p>\n

5. Dishwasher or washing machine connected to the sink<\/h4>\n

If your dishwasher or washing machine drains into the sink, they send a large amount of water through all at once, along with grease and detergent residue, which accelerates the build-up in the pipework. If, when you switch them on, you notice water rising up through the sink, this is a backflow: we\u2019ll explain the reasons why water rises up through the drain.<\/a><\/p>\n

6. The problem goes beyond the kitchen<\/h4>\n

If the sink shares a pipe with other appliances, the blockage may be located beyond the joint. In a flat, grease from several kitchens accumulates in the building\u2019s blocked downpipe<\/a>; in a house, it usually gets stuck in the first blocked trap<\/a>. And if the blockage returns even after it has been thoroughly cleared, there may be a crushed section of pipe or a misaligned joint \u2013 something common in old installations, as we explain in our guide on how to prevent recurring blockages in old buildings<\/a>. In that case, it is advisable to rule out a broken drainpipe<\/a>.<\/p>\n

How to find out where the blockage is in your sink<\/h4>\n

Take a look at how the sink behaves: it tells you quite a lot about where the plug is.<\/p>\n

\n\n\n\n\n\n\n\n\n\n
What you notice<\/th>\nMost likely cause<\/th>\nWhat\u2019s the problem?<\/th>\n<\/tr>\n<\/thead>\n
The water drains slowly and smells of grease or food<\/td>\nGrease and food scraps<\/td>\nSink trap and pipework<\/td>\n<\/tr>\n
You\u2019ll notice an improvement as soon as you clean the trap<\/td>\nA siphon that is dirty or clogged with soap and limescale<\/td>\nSiphon<\/td>\n<\/tr>\n
Water rises in the sink when the dishwasher is turned on<\/td>\nPartial obstruction on the shared section<\/td>\nStandard kitchen pipework<\/td>\n<\/tr>\n
The sink and other drains get blocked at the same time<\/td>\nCommon section, downpipe or manhole<\/td>\nHousing or building network<\/td>\n<\/tr>\n
It\u2019s blocked up again just a few days after it was unblocked<\/td>\nGrease build-up or damaged pipework<\/td>\nInside the pipe<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<\/div>\n

How to unblock a sink, step by step<\/h3>\n

If the blockage is in the trap or just beyond it, you can sort it out yourself in four steps. Follow them in this order, from least to most invasive.<\/p>\n

Step 1: Empty the bin and do not use the electrical appliances<\/h4>\n

Do not run the dishwasher or washing machine whilst the sink is blocked: each flush raises the water level. Use a container to remove any water from the sink.<\/p>\n

Step 2: Clean the trap<\/h4>\n

Place a bucket underneath, unscrew the trap and empty its contents. Wash it with hot soapy water, check that the seals are secure and reassemble it, tightening it firmly. In many sinks, this step is enough to clear the blockage.<\/p>\n

Step 3: Use the suction cup to cover the overflow<\/h4>\n

If the sink has an overflow or two basins, plug the other hole with a damp cloth so that the pressure doesn\u2019t escape. Place the plunger over the drain with a little water in it, and push and pull firmly several times.<\/p>\n

Step 4: warm soapy water and, if necessary, a sponge<\/h4>\n

A squirt of washing-up liquid followed by hot water will break down fresh grease. If the blockage is beyond the trap, insert a manual drain snake into the trap outlet, twist it as you push it in, and remove whatever comes out.<\/p>\n

What to avoid<\/h4>\n

Do not use caustic soda or chemical drain unblockers, and never mix different products. We explain why in our guide to common mistakes when trying to unblock pipes yourself<\/a>. If you\u2019re looking for a guide to any drain in the house, see our guide on how to clean drain pipes<\/a>.<\/p>\n

If, after following these steps, the sink becomes blocked again within a few days or weeks, the problem is no longer with the trap: there is grease build-up in the pipe or a blockage in a shared section, and household tools cannot reach that far.<\/p>\n

When your sink needs more than just unblocking<\/h3>\n

If the sink keeps getting blocked even though you\u2019ve cleaned the trap, the grease has already spread through the pipe. Unblocking it only clears a section; to stop it happening again, you need to clean the entire pipe. These signs indicate this:<\/p>\n